Provided by: openvswitch-switch_2.13.8-0ubuntu1.3_amd64 bug

NAME

       ovs-vswitchd.conf.db - Open_vSwitch database schema

       A  database with this schema holds the configuration for one Open vSwitch daemon. The top-
       level configuration for the daemon is the Open_vSwitch table, which must have exactly  one
       record.  Records in other tables are significant only when they can be reached directly or
       indirectly  from  the  Open_vSwitch  table.  Records  that  are  not  reachable  from  the
       Open_vSwitch  table  are  automatically deleted from the database, except for records in a
       few distinguished ``root set’’ tables.

   Common Columns
       Most tables contain two  special  columns,  named  other_config  and  external_ids.  These
       columns  have  the  same form and purpose each place that they appear, so we describe them
       here to save space later.

              other_config: map of string-string pairs
                     Key-value pairs for configuring rarely used features. Supported keys,  along
                     with  the  forms taken by their values, are documented individually for each
                     table.

                     A few tables do not have other_config columns  because  no  key-value  pairs
                     have yet been defined for them.

              external_ids: map of string-string pairs
                     Key-value  pairs  for  use  by  external frameworks that integrate with Open
                     vSwitch, rather than by  Open  vSwitch  itself.  System  integrators  should
                     either use the Open vSwitch development mailing list to coordinate on common
                     key-value definitions, or choose key names that are likely to be unique.  In
                     some  cases,  where  key-value pairs have been defined that are likely to be
                     widely useful, they are documented individually for each table.

TABLE SUMMARY

       The following list summarizes the purpose of  each  of  the  tables  in  the  Open_vSwitch
       database.  Each table is described in more detail on a later page.

       Table     Purpose
       Open_vSwitch
                 Open vSwitch configuration.
       Bridge    Bridge configuration.
       Port      Port configuration.
       Interface One physical network device in a Port.
       Flow_Table
                 OpenFlow table configuration
       QoS       Quality of Service configuration
       Queue     QoS output queue.
       Mirror    Port mirroring.
       Controller
                 OpenFlow controller configuration.
       Manager   OVSDB management connection.
       NetFlow   NetFlow configuration.
       Datapath  Datapath configuration.
       CT_Zone   CT_Zone configuration.
       CT_Timeout_Policy
                 CT_Timeout_Policy configuration.
       SSL       SSL configuration.
       sFlow     sFlow configuration.
       IPFIX     IPFIX configuration.
       Flow_Sample_Collector_Set
                 Flow_Sample_Collector_Set configuration.
       AutoAttach
                 AutoAttach configuration.

Open_vSwitch TABLE

       Configuration  for  an  Open  vSwitch  daemon.  There  must  be  exactly one record in the
       Open_vSwitch table.

   Summary:
       Configuration:
         datapaths                   map of string-Datapath pairs
         bridges                     set of Bridges
         ssl                         optional SSL
         external_ids : system-id    optional string
         external_ids : xs-system-uuid
                                     optional string
         external_ids : hostname     optional string
         external_ids : rundir       optional string
         other_config : stats-update-interval
                                     optional string, containing an integer, at least 5,000
         other_config : flow-restore-wait
                                     optional string, either true or false
         other_config : flow-limit   optional string, containing an integer, at least 0
         other_config : max-idle     optional string, containing an integer, at least 500
         other_config : max-revalidator
                                     optional string, containing an integer, at least 100
         other_config : min-revalidate-pps
                                     optional string, containing an integer, at least 1
         other_config : hw-offload   optional string, either true or false
         other_config : tc-policy    optional string, one of none, skip_hw, or skip_sw
         other_config : dpdk-init    optional string, one of false, true, or try
         other_config : dpdk-lcore-mask
                                     optional string, containing an integer, at least 1
         other_config : pmd-cpu-mask
                                     optional string
         other_config : dpdk-alloc-mem
                                     optional string, containing an integer, at least 0
         other_config : dpdk-socket-mem
                                     optional string
         other_config : dpdk-socket-limit
                                     optional string
         other_config : dpdk-hugepage-dir
                                     optional string
         other_config : dpdk-extra   optional string
         other_config : vhost-sock-dir
                                     optional string
         other_config : vhost-iommu-support
                                     optional string, either true or false
         other_config : vhost-postcopy-support
                                     optional string, either true or false
         other_config : per-port-memory
                                     optional string, either true or false
         other_config : tx-flush-interval
                                     optional string,  containing  an  integer,  in  range  0  to
                                     1,000,000
         other_config : pmd-perf-metrics
                                     optional string, either true or false
         other_config : smc-enable   optional string, either true or false
         other_config : pmd-rxq-assign
                                     optional string, either cycles or roundrobin
         other_config : n-handler-threads
                                     optional string, containing an integer, at least 1
         other_config : n-revalidator-threads
                                     optional string, containing an integer, at least 1
         other_config : emc-insert-inv-prob
                                     optional  string,  containing  an  integer,  in  range  0 to
                                     4,294,967,295
         other_config : vlan-limit   optional string, containing an integer, at least 0
         other_config : bundle-idle-timeout
                                     optional string, containing an integer, at least 1
         other_config : offload-rebalance
                                     optional string, either true or false
         other_config : pmd-auto-lb  optional string, either true or false
         other_config : pmd-auto-lb-rebal-interval
                                     optional string, containing an integer, in range 0 to 20,000
         other_config : userspace-tso-enable
                                     optional string, either true or false
       Status:
         next_cfg                    integer
         cur_cfg                     integer
         dpdk_initialized            boolean
         Statistics:
            other_config : enable-statistics
                                     optional string, either true or false
            statistics : cpu         optional string, containing an integer, at least 1
            statistics : load_average
                                     optional string
            statistics : memory      optional string
            statistics : process_NAME
                                     optional string
            statistics : file_systems
                                     optional string
       Version Reporting:
         ovs_version                 optional string
         db_version                  optional string
         system_type                 optional string
         system_version              optional string
         dpdk_version                optional string
       Capabilities:
         datapath_types              set of strings
         iface_types                 set of strings
       Database Configuration:
         manager_options             set of Managers
       IPsec:
         other_config : private_key  optional string
         other_config : certificate  optional string
         other_config : ca_cert      optional string
         Plaintext Tunnel Policy:
            other_config : ipsec_skb_mark
                                     optional string
       Common Columns:
         other_config                map of string-string pairs
         external_ids                map of string-string pairs

   Details:
     Configuration:

       datapaths: map of string-Datapath pairs
              Map of datapath types to datapaths. The datapath_type column of the Bridge table is
              used as a key for this map. The value points to a row in the Datapath table.

       bridges: set of Bridges
              Set of bridges managed by the daemon.

       ssl: optional SSL
              SSL used globally by the daemon.

       external_ids : system-id: optional string
              A  unique  identifier  for  the  Open  vSwitch’s  physical  host.  The  form of the
              identifier depends on the type of the host. On a Citrix XenServer, this will likely
              be the same as external_ids:xs-system-uuid.

       external_ids : xs-system-uuid: optional string
              The  Citrix  XenServer  universally  unique  identifier  for  the  physical host as
              displayed by xe host-list.

       external_ids : hostname: optional string
              The hostname for the host running Open vSwitch. This is a  fully  qualified  domain
              name since version 2.6.2.

       external_ids : rundir: optional string
              In  Open  vSwitch  2.8  and  later,  the  run directory of the running Open vSwitch
              daemon. This directory is used for runtime state such  as  control  and  management
              sockets. The value of other_config:vhost-sock-dir is relative to this directory.

       other_config  :  stats-update-interval:  optional  string, containing an integer, at least
       5,000
              Interval for updating statistics to the database, in milliseconds. This option will
              affect the update of the statistics column in the following tables: Port, Interface
              , Mirror.

              Default value is 5000 ms.

              Getting statistics more frequently can be achieved via OpenFlow.

       other_config : flow-restore-wait: optional string, either true or false
              When ovs-vswitchd starts up, it has an empty flow table and  therefore  it  handles
              all  arriving  packets  in  its  default fashion according to its configuration, by
              dropping them or sending them to an OpenFlow controller  or  switching  them  as  a
              standalone  switch. This behavior is ordinarily desirable. However, if ovs-vswitchd
              is restarting as part of a ``hot-upgrade,’’ then this leads to  a  relatively  long
              period during which packets are mishandled.

              This option allows for improvement. When ovs-vswitchd starts with this value set as
              true, it will neither flush or expire previously set datapath  flows  nor  will  it
              send  and receive any packets to or from the datapath. When this value is later set
              to false, ovs-vswitchd will start receiving packets from the datapath and  re-setup
              the flows.

              Additionally,  ovs-vswitchd  is  prevented from connecting to controllers when this
              value is set to true. This prevents controllers from making  changes  to  the  flow
              table  in  the  middle  of  flow  restoration,  which  could  result in undesirable
              intermediate states. Once this value has been set to false  and  the  desired  flow
              state  has been restored, ovs-vswitchd will be able to reconnect to controllers and
              process any new flow table modifications.

              Thus, with this option, the procedure for a  hot-upgrade  of  ovs-vswitchd  becomes
              roughly the following:

              1.  Stop ovs-vswitchd.

              2.  Set other_config:flow-restore-wait to true.

              3.  Start ovs-vswitchd.

              4.  Use  ovs-ofctl  (or  some  other  program,  such  as an OpenFlow controller) to
                  restore the OpenFlow flow table to the desired state.

              5.  Set other_config:flow-restore-wait to false (or remove  it  entirely  from  the
                  database).

              The  ovs-ctl’s ``restart’’ and ``force-reload-kmod’’ functions use the above config
              option during hot upgrades.

       other_config : flow-limit: optional string, containing an integer, at least 0
              The maximum number of flows allowed in the datapath flow table. Internally OVS will
              choose a flow limit which will likely be lower than this number, based on real time
              network conditions. Tweaking this value is discouraged unless you know exactly what
              you’re doing.

              The default is 200000.

       other_config : max-idle: optional string, containing an integer, at least 500
              The  maximum  time  (in  ms)  that  idle  flows will remain cached in the datapath.
              Internally OVS will check the validity and activity for  datapath  flows  regularly
              and  may  expire  flows  quicker  than  this  number,  based  on  real time network
              conditions. Tweaking this value is discouraged unless you know exactly what  you’re
              doing.

              The default is 10000.

       other_config : max-revalidator: optional string, containing an integer, at least 100
              The  maximum  time (in ms) that revalidator threads will wait before executing flow
              revalidation. Note that this is maximum allowed value. Actual timeout used  by  OVS
              is  minimum  of  max-idle  and  max-revalidator  values.  Tweaking  this  value  is
              discouraged unless you know exactly what you’re doing.

              The default is 500.

       other_config : min-revalidate-pps: optional string, containing an integer, at least 1
              Set minimum pps that flow must have in order to be  revalidated  when  revalidation
              duration exceeds half of max-revalidator config variable.

              The default is 5.

       other_config : hw-offload: optional string, either true or false
              Set this value to true to enable netdev flow offload.

              The default value is false. Changing this value requires restarting the daemon

              Currently  Open  vSwitch  supports  hardware  offloading on Linux systems. On other
              systems, this value is ignored. This functionality  is  considered  ’experimental’.
              Depending  on  which  OpenFlow  matches  and  actions  are configured, which kernel
              version is used, and what hardware is available, Open vSwitch may not  be  able  to
              offload functionality to hardware.

              In  order  to  dump  HW  offloaded flows use ovs-appctl dpctl/dump-flows, ovs-dpctl
              doesn’t support this functionality. See ovs-vswitchd(8) for details.

       other_config : tc-policy: optional string, one of none, skip_hw, or skip_sw
              Specified the policy used with HW offloading. Options:

              none   Add software rule and offload rule to HW.

              skip_sw
                     Offload rule to HW only.

              skip_hw
                     Add software rule without offloading rule to HW.

              This is only relevant if other_config:hw-offload is enabled.

              The default value is none.

       other_config : dpdk-init: optional string, one of false, true, or try
              Set this value to true or try to enable runtime support for DPDK ports. The vswitch
              must have compile-time support for DPDK as well.

              A  value  of  true  will  cause the ovs-vswitchd process to abort if DPDK cannot be
              initialized. A value of try will allow the ovs-vswitchd process to continue running
              even if DPDK cannot be initialized.

              The default value is false. Changing this value requires restarting the daemon

              If  this  value  is  false  at  startup, any dpdk ports which are configured in the
              bridge will fail due to memory errors.

       other_config : dpdk-lcore-mask: optional string, containing an integer, at least 1
              Specifies the CPU cores where dpdk lcore threads should be spawned. The DPDK  lcore
              threads  are  used  for  DPDK  library  tasks,  such  as  library  internal message
              processing, logging, etc. Value should be in the form of a hex string (so  ’0x123’)
              similar to the ’taskset’ mask input.

              The  lowest  order  bit  corresponds  to  the  first  CPU core. A set bit means the
              corresponding core is available and an lcore thread will be created and  pinned  to
              it. If the input does not cover all cores, those uncovered cores are considered not
              set.

              For performance reasons, it is best to set this to a single  core  on  the  system,
              rather than allow lcore threads to float.

              If not specified, the value will be determined by choosing the lowest CPU core from
              initial cpu affinity list. Otherwise, the value will be passed directly to the DPDK
              library.

       other_config : pmd-cpu-mask: optional string
              Specifies  CPU mask for setting the cpu affinity of PMD (Poll Mode Driver) threads.
              Value should be in the form of hex string, similar to the dpdk  EAL  ’-c  COREMASK’
              option input or the ’taskset’ mask input.

              The  lowest  order  bit  corresponds  to  the  first  CPU core. A set bit means the
              corresponding core is available and a pmd thread will be created and pinned to  it.
              If  the  input  does  not cover all cores, those uncovered cores are considered not
              set.

              If not specified, one pmd thread will be created for each numa node and  pinned  to
              any available core on the numa node by default.

       other_config : dpdk-alloc-mem: optional string, containing an integer, at least 0
              Specifies the amount of memory to preallocate from the hugepage pool, regardless of
              socket. It is recommended that dpdk-socket-mem is used instead.

       other_config : dpdk-socket-mem: optional string
              Specifies the amount of memory to preallocate from the hugepage  pool,  on  a  per-
              socket basis.

              The  specifier  is a comma-separated string, in ascending order of CPU socket. E.g.
              On a four socket system 1024,0,2048 would  set  socket  0  to  preallocate  1024MB,
              socket  1 to preallocate 0MB, socket 2 to preallocate 2048MB and socket 3 (no value
              given) to preallocate 0MB.

              If dpdk-socket-mem and dpdk-alloc-mem are not specified,  dpdk-socket-mem  will  be
              used and the default value is 1024 for each numa node. If dpdk-socket-mem and dpdk-
              alloc-mem are specified at same time, dpdk-socket-mem  will  be  used  as  default.
              Changing this value requires restarting the daemon.

       other_config : dpdk-socket-limit: optional string
              Limits  the  maximum amount of memory that can be used from the hugepage pool, on a
              per-socket basis.

              The specifier is a comma-separated list of memory limits per socket. 0 will disable
              the limit for a particular socket.

              If  not  specified,  OVS  will configure limits equal to the amount of preallocated
              memory   specified   by    other_config:dpdk-socket-mem    or    --socket-mem    in
              other_config:dpdk-extra.  If  none  of  the above options specified or --legacy-mem
              provided in other_config:dpdk-extra, limits will  not  be  applied.  Changing  this
              value requires restarting the daemon.

       other_config : dpdk-hugepage-dir: optional string
              Specifies the path to the hugetlbfs mount point.

              If   not  specified,  this  will  be  guessed  by  the  DPDK  library  (default  is
              /dev/hugepages). Changing this value requires restarting the daemon.

       other_config : dpdk-extra: optional string
              Specifies additional eal command line arguments for DPDK.

              The default is empty. Changing this value requires restarting the daemon

       other_config : vhost-sock-dir: optional string
              Specifies a relative path from external_ids:rundir to the  vhost-user  unix  domain
              socket   files.   If  this  value  is  unset,  the  sockets  are  put  directly  in
              external_ids:rundir.

              Changing this value requires restarting the daemon.

       other_config : vhost-iommu-support: optional string, either true or false
              vHost IOMMU is a security feature, which restricts the vhost memory that  a  virtio
              device may access. vHost IOMMU support is disabled by default, due to a bug in QEMU
              implementations of the vhost REPLY_ACK protocol,  (on  which  vHost  IOMMU  relies)
              prior  to  v2.9.1. Setting this value to true enables vHost IOMMU support for vHost
              User Client ports in OvS-DPDK, starting from DPDK v17.11.

              Changing this value requires restarting the daemon.

       other_config : vhost-postcopy-support: optional string, either true or false
              vHost post-copy is a feature which allows switching live migration of  VM  attached
              to dpdkvhostuserclient port to post-copy mode if default pre-copy migration can not
              be converged or takes too long to converge. Setting  this  value  to  true  enables
              vHost  post-copy support for all dpdkvhostuserclient ports. Available starting from
              DPDK v18.11 and QEMU 2.12.

              Changing this value requires restarting the daemon.

       other_config : per-port-memory: optional string, either true or false
              By default OVS DPDK uses a shared memory model wherein devices that have  the  same
              MTU  and  socket  values  can  share  the  same mempool. Setting this value to true
              changes this behaviour. Per port memory allow DPDK devices to  use  private  memory
              per  device.  This  can  provide  greater  transparency as regards memory usage but
              potentially at the cost of greater memory requirements.

              Changing this value requires restarting the daemon if dpdk-init  has  already  been
              set to true.

       other_config  :  tx-flush-interval:  optional string, containing an integer, in range 0 to
       1,000,000
              Specifies the time in microseconds that a packet  can  wait  in  output  batch  for
              sending  i.e.  amount of time that packet can spend in an intermediate output queue
              before sending to netdev. This option can be  used  to  configure  balance  between
              throughput  and  latency. Lower values decreases latency while higher values may be
              useful to achieve higher performance.

              Defaults to 0 i.e. instant packet sending (latency optimized).

       other_config : pmd-perf-metrics: optional string, either true or false
              Enables recording of detailed PMD performance metrics  for  analysis  and  trouble-
              shooting. This can have a performance impact in the order of 1%.

              Defaults to false but can be changed at any time.

       other_config : smc-enable: optional string, either true or false
              Signature match cache or SMC is a cache between EMC and megaflow cache. It does not
              store the full key of the flow, so it is more memory  efficient  comparing  to  EMC
              cache. SMC is especially useful when flow count is larger than EMC capacity.

              Defaults to false but can be changed at any time.

       other_config : pmd-rxq-assign: optional string, either cycles or roundrobin
              Specifies how RX queues will be automatically assigned to CPU cores. Options:

              cycles Rxqs  will  be  sorted  by  order of measured processing cycles before being
                     assigned to CPU cores.

              roundrobin
                     Rxqs will be round-robined across CPU cores.

              The default value is cycles.

              Changing this value will affect an automatic re-assignment of Rxqs to  CPUs.  Note:
              Rxqs mapped to CPU cores with pmd-rxq-affinity are unaffected.

       other_config : n-handler-threads: optional string, containing an integer, at least 1
              Specifies  the  number  of  threads  for software datapaths to use for handling new
              flows. The default the number of online CPU cores minus the number of revalidators.

              This configuration is per datapath. If you have more  than  one  software  datapath
              (e.g.  some  system  bridges  and  some  netdev  bridges), then the total number of
              threads is n-handler-threads times the number of software datapaths.

       other_config : n-revalidator-threads: optional string, containing an integer, at least 1
              Specifies the number of threads for software  datapaths  to  use  for  revalidating
              flows  in the datapath. Typically, there is a direct correlation between the number
              of revalidator threads, and the number  of  flows  allowed  in  the  datapath.  The
              default  is  the number of cpu cores divided by four plus one. If n-handler-threads
              is set, the default changes to the number of cpu cores minus the number of  handler
              threads.

              This  configuration  is  per  datapath. If you have more than one software datapath
              (e.g. some system bridges and some  netdev  bridges),  then  the  total  number  of
              threads is n-handler-threads times the number of software datapaths.

       other_config  : emc-insert-inv-prob: optional string, containing an integer, in range 0 to
       4,294,967,295
              Specifies the inverse probability (1/emc-insert-inv-prob) of a flow being  inserted
              into  the  Exact  Match  Cache  (EMC).  On average one in every emc-insert-inv-prob
              packets that generate a unique flow will cause an insertion into the EMC.  A  value
              of  1  will  result  in an insertion for every flow (1/1 = 100%) whereas a value of
              zero will result in no insertions and essentially disable the EMC.

              Defaults to 100 ie. there is (1/100 =) 1% chance of EMC insertion.

       other_config : vlan-limit: optional string, containing an integer, at least 0
              Limits the number of VLAN headers that can be  matched  to  the  specified  number.
              Further  VLAN  headers  will  be treated as payload, e.g. a packet with more 802.1q
              headers will match Ethernet type 0x8100.

              Open vSwitch userspace currently supports at most 2 VLANs, and  each  datapath  has
              its own limit. If vlan-limit is nonzero, it acts as a further limit.

              If  this  value  is  absent,  the  default  is currently 1. This maintains backward
              compatibility with controllers  that  were  designed  for  use  with  Open  vSwitch
              versions earlier than 2.8, which only supported one VLAN.

       other_config : bundle-idle-timeout: optional string, containing an integer, at least 1
              The  maximum  time  (in seconds) that idle bundles will wait to be expired since it
              was either opened, modified or closed.

              OpenFlow specification mandates the timeout to be at least one second. The  default
              is 10 seconds.

       other_config : offload-rebalance: optional string, either true or false
              Configures  HW  offload  rebalancing,  that  allows  to dynamically offload and un-
              offload flows while an offload-device is out of resources (OOR). This policy allows
              flows  to  be selected for offloading based on the packets-per-second (pps) rate of
              flows.

              Set this value to true to enable this option.

              The default value is false. Changing this value requires restarting the daemon.

              This is only relevant if HW offloading is enabled (hw-offload). When this policy is
              enabled, it also requires ’tc-policy’ to be set to ’skip_sw’.

       other_config : pmd-auto-lb: optional string, either true or false
              Configures PMD Auto Load Balancing that allows automatic assignment of RX queues to
              PMDs if any of PMDs is overloaded (i.e. processing cycles > 95%).

              It uses current scheme of  cycle  based  assignment  of  RX  queues  that  are  not
              statically pinned to PMDs.

              The default value is false.

              Set  this  value to true to enable this option. It is currently disabled by default
              and an experimental feature.

              This only comes in effect if cycle based assignment is enabled and there  are  more
              than  one  non-isolated  PMDs  present  and  at least one of it polls more than one
              queue.

       other_config : pmd-auto-lb-rebal-interval: optional  string,  containing  an  integer,  in
       range 0 to 20,000
              The minimum time (in minutes) 2 consecutive PMD Auto Load Balancing iterations.

              The defaul value is 1 min. If configured to 0 then it would be converted to default
              value i.e. 1 min

              This option can be configured to avoid frequent trigger of auto load  balancing  of
              PMDs.  For  e.g.  set the value (in min) such that it occurs once in few hours or a
              day or a week.

       other_config : userspace-tso-enable: optional string, either true or false
              Set this value to true to enable userspace support for TCP Segmentation  Offloading
              (TSO).  When  it is enabled, the interfaces can provide an oversized TCP segment to
              the datapath and the datapath  will  offload  the  TCP  segmentation  and  checksum
              calculation to the interfaces when necessary.

              The default value is false. Changing this value requires restarting the daemon.

              The feature only works if Open vSwitch is built with DPDK support.

              The feature is considered experimental.

     Status:

       next_cfg: integer
              Sequence  number  for  client  to increment. When a client modifies any part of the
              database configuration and wishes to wait for Open vSwitch to finish  applying  the
              changes, it may increment this sequence number.

       cur_cfg: integer
              Sequence  number  that  Open vSwitch sets to the current value of next_cfg after it
              finishes applying a set of configuration changes.

       dpdk_initialized: boolean
              True if other_config:dpdk-init is set to true and the DPDK library is  successfully
              initialized.

     Statistics:

       The  statistics  column  contains  key-value  pairs  that report statistics about a system
       running an Open vSwitch. These are updated periodically (currently, every 5 seconds). Key-
       value pairs that cannot be determined or that do not apply to a platform are omitted.

       other_config : enable-statistics: optional string, either true or false
              Statistics  are  disabled  by  default  to  avoid  overhead in the common case when
              statistics gathering is not useful. Set this value to true to enable populating the
              statistics column or to false to explicitly disable it.

       statistics : cpu: optional string, containing an integer, at least 1
              Number  of  CPU processors, threads, or cores currently online and available to the
              operating system on which Open vSwitch is running, as an integer. This may be  less
              than  the  number installed, if some are not online or if they are not available to
              the operating system.

              Open vSwitch userspace processes are not multithreaded, but the Linux  kernel-based
              datapath is.

       statistics : load_average: optional string
              A  comma-separated  list  of  three floating-point numbers, representing the system
              load average over the last 1, 5, and 15 minutes, respectively.

       statistics : memory: optional string
              A comma-separated list of integers, each of which represents a quantity  of  memory
              in  kilobytes that describes the operating system on which Open vSwitch is running.
              In respective order, these values are:

              1.  Total amount of RAM allocated to the OS.

              2.  RAM allocated to the OS that is in use.

              3.  RAM that can be flushed out to disk or otherwise discarded  if  that  space  is
                  needed  for  another  purpose. This number is necessarily less than or equal to
                  the previous value.

              4.  Total disk space allocated for swap.

              5.  Swap space currently in use.

              On Linux, all five values can be determined and are included.  On  other  operating
              systems,  only  the  first two values can be determined, so the list will only have
              two values.

       statistics : process_NAME: optional string
              One such key-value pair, with NAME replaced by a process name, will exist for  each
              running  Open vSwitch daemon process, with name replaced by the daemon’s name (e.g.
              process_ovs-vswitchd). The  value  is  a  comma-separated  list  of  integers.  The
              integers  represent  the following, with memory measured in kilobytes and durations
              in milliseconds:

              1.  The process’s virtual memory size.

              2.  The process’s resident set size.

              3.  The amount of user and system CPU time consumed by the process.

              4.  The number of times  that  the  process  has  crashed  and  been  automatically
                  restarted by the monitor.

              5.  The duration since the process was started.

              6.  The duration for which the process has been running.

              The  interpretation  of  some  of  these  values depends on whether the process was
              started with the --monitor. If it was not, then the crash count will  always  be  0
              and  the  two  durations  will always be the same. If --monitor was given, then the
              crash count may be positive; if it is, the latter duration is the  amount  of  time
              since the most recent crash and restart.

              There  will be one key-value pair for each file in Open vSwitch’s ``run directory’’
              (usually /var/run/openvswitch) whose name  ends  in  .pid,  whose  contents  are  a
              process  ID,  and  which is locked by a running process. The name is taken from the
              pidfile’s name.

              Currently Open vSwitch is only able to obtain all of  the  above  detail  on  Linux
              systems.  On other systems, the same key-value pairs will be present but the values
              will always be the empty string.

       statistics : file_systems: optional string
              A space-separated list of information on local, writable file systems. Each item in
              the  list  describes one file system and consists in turn of a comma-separated list
              of the following:

              1.  Mount point, e.g. / or /var/log. Any spaces or commas in the  mount  point  are
                  replaced by underscores.

              2.  Total size, in kilobytes, as an integer.

              3.  Amount of storage in use, in kilobytes, as an integer.

              This  key-value  pair is omitted if there are no local, writable file systems or if
              Open vSwitch cannot obtain the needed information.

     Version Reporting:

       These columns report the types and versions of the  hardware  and  software  running  Open
       vSwitch.  We  recommend in general that software should test whether specific features are
       supported instead of relying on version number checks. These values are primarily intended
       for reporting to human administrators.

       ovs_version: optional string
              The Open vSwitch version number, e.g. 1.1.0.

       db_version: optional string
              The   database  schema  version  number,  e.g.  1.2.3.  See  ovsdb-tool(1)  for  an
              explanation of the numbering scheme.

              The schema version is part of the database schema, so it can also be  retrieved  by
              fetching the schema using the Open vSwitch database protocol.

       system_type: optional string
              An  identifier  for  the  type  of  system  on top of which Open vSwitch runs, e.g.
              XenServer or KVM.

              System integrators are responsible for choosing and setting  an  appropriate  value
              for this column.

       system_version: optional string
              The  version  of  the  system  identified  by  system_type,  e.g. 5.6.100-39265p on
              XenServer 5.6.100 build 39265.

              System integrators are responsible for choosing and setting  an  appropriate  value
              for this column.

       dpdk_version: optional string
              The version of the linked DPDK library.

     Capabilities:

       These columns report capabilities of the Open vSwitch instance.

       datapath_types: set of strings
              This  column  reports the different dpifs registered with the system. These are the
              values that this instance supports in the datapath_type column of the Bridge table.

       iface_types: set of strings
              This column reports the different netdevs registered with the system. These are the
              values that this instance supports in the type column of the Interface table.

     Database Configuration:

       These  columns  primarily configure the Open vSwitch database (ovsdb-server), not the Open
       vSwitch switch (ovs-vswitchd). The OVSDB database also uses the ssl settings.

       The Open vSwitch switch does read  the  database  configuration  to  determine  remote  IP
       addresses to which in-band control should apply.

       manager_options: set of Managers
              Database  clients  to  which  the Open vSwitch database server should connect or to
              which it should listen, along with options for  how  these  connections  should  be
              configured. See the Manager table for more information.

              For  this column to serve its purpose, ovsdb-server must be configured to honor it.
              The  easiest  way  to  do  this  is  to  invoke  ovsdb-server   with   the   option
              --remote=db:Open_vSwitch,Open_vSwitch,manager_options   The  startup  scripts  that
              accompany Open vSwitch do this by default.

     IPsec:

       These settings control the global configuration of IPsec tunnels. The  options  column  of
       the Interface table configures IPsec for individual tunnels.

       OVS  IPsec  supports  the  following  three  forms of authentication. Currently, all IPsec
       tunnels must use the same form:

              1.  Pre-shared keys: Omit the global settings. On each tunnel, set options:psk.

              2.  Self-signed certificates: Set the private_key and certificate global  settings.
                  On  each  tunnel,  set options:remote_cert. The remote certificate can be self-
                  signed.

              3.  CA-signed certificates: Set all of the global settings.  On  each  tunnel,  set
                  options:remote_name  to  the  common  name  (CN) of the remote certificate. The
                  remote certificate must be signed by the CA.

       other_config : private_key: optional string
              Name of a PEM file containing the private key used as  the  switch’s  identity  for
              IPsec tunnels.

       other_config : certificate: optional string
              Name  of  a  PEM  file containing a certificate that certifies the switch’s private
              key, and identifies a trustworthy switch for IPsec tunnels. The certificate must be
              x.509  version  3  and  with the string in common name (CN) also set in the subject
              alternative name (SAN).

       other_config : ca_cert: optional string
              Name of a PEM file containing the CA certificate  used  to  verify  that  a  remote
              switch of the IPsec tunnel is trustworthy.

     Plaintext Tunnel Policy:

       When  an IPsec tunnel is configured in this database, multiple independent components take
       responsibility for implementing it. ovs-vswitchd and its datapath handle packet forwarding
       to  the tunnel and a separate daemon pushes the tunnel’s IPsec policy configuration to the
       kernel or other entity that implements it. There is a race: if  the  former  configuration
       completes  before  the  latter, then packets sent by the local host over the tunnel can be
       transmitted in plaintext. Using  this  setting,  OVS  users  can  avoid  this  undesirable
       situation.

       other_config : ipsec_skb_mark: optional string
              This setting takes the form value/mask. If it is specified, then the skb_mark field
              in every outgoing tunneled packet sent in plaintext is compared against it and,  if
              it  matches,  the  packet  is  dropped. This is a global setting that is applied to
              every tunneled packet, regardless of whether IPsec encryption is  enabled  for  the
              tunnel, the type of tunnel, or whether OVS is involved.

              Example policies:

              1/1    Drop  all unencrypted tunneled packets in which the least-significant bit of
                     skb_mark is 1. This would be a useful policy given an  OpenFlow  flow  table
                     that  sets  skb_mark  to 1 for traffic that should be encrypted. The default
                     skb_mark is 0, so this would not affect other traffic.

              0/1    Drop all unencrypted tunneled packets in which the least-significant bit  of
                     skb_mark  is  0.  This  would  be a useful policy if no unencrypted tunneled
                     traffic should exit  the  system  without  being  specially  whitelisted  by
                     setting skb_mark to 1.

              (empty)
                     If this setting is empty or unset, then all unencrypted tunneled packets are
                     transmitted in the usual way.

     Common Columns:

       The overall purpose of these columns is described under Common Columns at the beginning of
       this document.

       other_config: map of string-string pairs

       external_ids: map of string-string pairs

Bridge TABLE

       Configuration for a bridge within an Open_vSwitch.

       A  Bridge  record  represents an Ethernet switch with one or more ``ports,’’ which are the
       Port records pointed to by the Bridge’s ports column.

   Summary:
       Core Features:
         name                        immutable string (must be unique within table)
         ports                       set of Ports
         mirrors                     set of Mirrors
         netflow                     optional NetFlow
         sflow                       optional sFlow
         ipfix                       optional IPFIX
         flood_vlans                 set of up to 4,096 integers, in range 0 to 4,095
         auto_attach                 optional AutoAttach
       OpenFlow Configuration:
         controller                  set of Controllers
         flow_tables                 map of integer-Flow_Table pairs, key in range 0 to 254
         fail_mode                   optional string, either secure or standalone
         datapath_id                 optional string
         datapath_version            string
         other_config : datapath-id  optional string
         other_config : dp-desc      optional string
         other_config : disable-in-band
                                     optional string, either true or false
         other_config : in-band-queue
                                     optional string,  containing  an  integer,  in  range  0  to
                                     4,294,967,295
         other_config : controller-queue-size
                                     optional string, containing an integer, in range 1 to 512
         protocols                   set  of  strings, one of OpenFlow10, OpenFlow11, OpenFlow12,
                                     OpenFlow13, OpenFlow14, or OpenFlow15
       Spanning Tree Configuration:
         STP Configuration:
            stp_enable               boolean
            other_config : stp-system-id
                                     optional string
            other_config : stp-priority
                                     optional string, containing an integer, in range 0 to 65,535
            other_config : stp-hello-time
                                     optional string, containing an integer, in range 1 to 10
            other_config : stp-max-age
                                     optional string, containing an integer, in range 6 to 40
            other_config : stp-forward-delay
                                     optional string, containing an integer, in range 4 to 30
            other_config : mcast-snooping-aging-time
                                     optional string, containing an integer, at least 1
            other_config : mcast-snooping-table-size
                                     optional string, containing an integer, at least 1
            other_config : mcast-snooping-disable-flood-unregistered
                                     optional string, either true or false
         STP Status:
            status : stp_bridge_id   optional string
            status : stp_designated_root
                                     optional string
            status : stp_root_path_cost
                                     optional string
       Rapid Spanning Tree:
         RSTP Configuration:
            rstp_enable              boolean
            other_config : rstp-address
                                     optional string
            other_config : rstp-priority
                                     optional string, containing an integer, in range 0 to 61,440
            other_config : rstp-ageing-time
                                     optional string, containing  an  integer,  in  range  10  to
                                     1,000,000
            other_config : rstp-force-protocol-version
                                     optional string, containing an integer
            other_config : rstp-max-age
                                     optional string, containing an integer, in range 6 to 40
            other_config : rstp-forward-delay
                                     optional string, containing an integer, in range 4 to 30
            other_config : rstp-transmit-hold-count
                                     optional string, containing an integer, in range 1 to 10
         RSTP Status:
            rstp_status : rstp_bridge_id
                                     optional string
            rstp_status : rstp_root_id
                                     optional string
            rstp_status : rstp_root_path_cost
                                     optional string, containing an integer, at least 0
            rstp_status : rstp_designated_id
                                     optional string
            rstp_status : rstp_designated_port_id
                                     optional string
            rstp_status : rstp_bridge_port_id
                                     optional string
       Multicast Snooping Configuration:
         mcast_snooping_enable       boolean
       Other Features:
         datapath_type               string
         external_ids : bridge-id    optional string
         external_ids : xs-network-uuids
                                     optional string
         other_config : hwaddr       optional string
         other_config : forward-bpdu
                                     optional string, either true or false
         other_config : mac-aging-time
                                     optional string, containing an integer, at least 1
         other_config : mac-table-size
                                     optional string, containing an integer, at least 1
       Common Columns:
         other_config                map of string-string pairs
         external_ids                map of string-string pairs

   Details:
     Core Features:

       name: immutable string (must be unique within table)
              Bridge identifier. Must be unique among the names of ports, interfaces, and bridges
              on a host.

              The name must be alphanumeric and must not contain forward or backward slashes. The
              name  of  a bridge is also the name of an Interface (and a Port) within the bridge,
              so the restrictions on the name column in  the  Interface  table,  particularly  on
              length,  also apply to bridge names. Refer to the documentation for Interface names
              for details.

       ports: set of Ports
              Ports included in the bridge.

       mirrors: set of Mirrors
              Port mirroring configuration.

       netflow: optional NetFlow
              NetFlow configuration.

       sflow: optional sFlow
              sFlow(R) configuration.

       ipfix: optional IPFIX
              IPFIX configuration.

       flood_vlans: set of up to 4,096 integers, in range 0 to 4,095
              VLAN IDs of VLANs on which MAC address learning should be disabled, so that packets
              are  flooded  instead  of being sent to specific ports that are believed to contain
              packets’ destination MACs. This should ordinarily be used to disable  MAC  learning
              on VLANs used for mirroring (RSPAN VLANs). It may also be useful for debugging.

              SLB  bonding  (see  the  bond_mode  column  in the Port table) is incompatible with
              flood_vlans. Consider using another bonding mode or  a  different  type  of  mirror
              instead.

       auto_attach: optional AutoAttach
              Auto Attach configuration.

     OpenFlow Configuration:

       controller: set of Controllers
              OpenFlow controller set. If unset, then no OpenFlow controllers will be used.

              If  there  are  primary  controllers, removing all of them clears the OpenFlow flow
              tables, group table, and meter table. If there are no primary  controllers,  adding
              one  also  clears  these  tables.  Other changes to the set of controllers, such as
              adding or removing a service  controller,  adding  another  primary  controller  to
              supplement  an  existing  primary  controller,  or removing only one of two primary
              controllers, have no effect on these tables.

       flow_tables: map of integer-Flow_Table pairs, key in range 0 to 254
              Configuration for OpenFlow tables. Each pair maps from  an  OpenFlow  table  ID  to
              configuration for that table.

       fail_mode: optional string, either secure or standalone
              When  a controller is configured, it is, ordinarily, responsible for setting up all
              flows on the switch. Thus, if the  connection  to  the  controller  fails,  no  new
              network  connections  can be set up. If the connection to the controller stays down
              long enough, no packets can pass through the switch at all. This setting determines
              the switch’s response to such a situation. It may be set to one of the following:

              standalone
                     If no message is received from the controller for three times the inactivity
                     probe interval (see inactivity_probe), then  Open  vSwitch  will  take  over
                     responsibility  for  setting up flows. In this mode, Open vSwitch causes the
                     bridge to act like  an  ordinary  MAC-learning  switch.  Open  vSwitch  will
                     continue  to  retry connecting to the controller in the background and, when
                     the connection succeeds, it will discontinue its standalone behavior.

              secure Open vSwitch will not set up flows on its own when the controller connection
                     fails  or when no controllers are defined. The bridge will continue to retry
                     connecting to any defined controllers forever.

              The default is standalone if the value  is  unset,  but  future  versions  of  Open
              vSwitch may change the default.

              The  standalone mode can create forwarding loops on a bridge that has more than one
              uplink port unless STP is enabled. To avoid  loops  on  such  a  bridge,  configure
              secure mode or enable STP (see stp_enable).

              The  fail_mode  setting  applies  only  to  primary controllers. When more than one
              primary controller is configured, fail_mode is considered only  when  none  of  the
              configured controllers can be contacted.

              Changing  fail_mode  when no primary controllers are configured clears the OpenFlow
              flow tables, group table, and meter table.

       datapath_id: optional string
              Reports the OpenFlow datapath ID in use.  Exactly  16  hex  digits.  (Setting  this
              column has no useful effect. Set other-config:datapath-id instead.)

       datapath_version: string
              Reports   the   datapath   version.   This   column  is  maintained  for  backwards
              compatibility. The preferred locatation is the datapath_id column of  the  Datapath
              table. The full documentation for this column is there.

       other_config : datapath-id: optional string
              Overrides  the  default  OpenFlow  datapath  ID,  setting it to the specified value
              specified in hex. The value must either have a 0x  prefix  or  be  exactly  16  hex
              digits long. May not be all-zero.

       other_config : dp-desc: optional string
              Human  readable  description  of  datapath. It is a maximum 256 byte-long free-form
              string to describe the datapath for debugging purposes, e.g. switch3 in room 3120.

       other_config : disable-in-band: optional string, either true or false
              If set to true, disable in-band control on the bridge regardless of controller  and
              manager settings.

       other_config  :  in-band-queue:  optional  string,  containing  an  integer, in range 0 to
       4,294,967,295
              A queue ID as a nonnegative integer. This sets the OpenFlow queue ID that  will  be
              used  by  flows  set up by in-band control on this bridge. If unset, or if the port
              used by an in-band control flow does not have QoS configured, or if the  port  does
              not have a queue with the specified ID, the default queue is used instead.

       other_config  :  controller-queue-size: optional string, containing an integer, in range 1
       to 512
              This sets the maximum size of the queue of packets that need  to  be  sent  to  the
              OpenFlow  management  controller. The value must be less than 512. If not specified
              the queue size is limited to 100 packets by default.  Note:  increasing  the  queue
              size might have a negative impact on latency.

       protocols:  set  of  strings,  one  of  OpenFlow10,  OpenFlow11,  OpenFlow12,  OpenFlow13,
       OpenFlow14, or OpenFlow15
              List of OpenFlow protocols that may be used when negotiating a  connection  with  a
              controller.  OpenFlow  1.0,  1.1,  1.2, 1.3, 1.4, and 1.5 are enabled by default if
              this column is empty.

     Spanning Tree Configuration:

       The IEEE 802.1D Spanning Tree Protocol (STP) is a network protocol that ensures  loop-free
       topologies.  It  allows redundant links to be included in the network to provide automatic
       backup paths if the active links fails.

       These settings configure the slower-to-converge but  still  widely  supported  version  of
       Spanning  Tree  Protocol,  sometimes  known as 802.1D-1998. Open vSwitch also supports the
       newer Rapid Spanning Tree Protocol (RSTP), documented later in the  section  titled  Rapid
       Spanning Tree Configuration.

     STP Configuration:

       stp_enable: boolean
              Enable  spanning  tree on the bridge. By default, STP is disabled on bridges. Bond,
              internal, and mirror ports are not  supported  and  will  not  participate  in  the
              spanning tree.

              STP and RSTP are mutually exclusive. If both are enabled, RSTP will be used.

       other_config : stp-system-id: optional string
              The  bridge’s  STP  identifier  (the  lower  48  bits of the bridge-id) in the form
              xx:xx:xx:xx:xx:xx. By default, the identifier is the MAC address of the bridge.

       other_config : stp-priority: optional string, containing an integer, in range 0 to 65,535
              The bridge’s relative priority value for determining the root bridge (the upper  16
              bits  of the bridge-id). A bridge with the lowest bridge-id is elected the root. By
              default, the priority is 0x8000.

       other_config : stp-hello-time: optional string, containing an integer, in range 1 to 10
              The interval between transmissions  of  hello  messages  by  designated  ports,  in
              seconds. By default the hello interval is 2 seconds.

       other_config : stp-max-age: optional string, containing an integer, in range 6 to 40
              The  maximum  age  of the information transmitted by the bridge when it is the root
              bridge, in seconds. By default, the maximum age is 20 seconds.

       other_config : stp-forward-delay: optional string, containing an integer, in range 4 to 30
              The delay to wait between transitioning root and designated ports to forwarding, in
              seconds. By default, the forwarding delay is 15 seconds.

       other_config : mcast-snooping-aging-time: optional string, containing an integer, at least
       1
              The maximum number of seconds to retain a multicast snooping  entry  for  which  no
              packets  have  been  seen.  The  default  is currently 300 seconds (5 minutes). The
              value, if specified, is forced into  a  reasonable  range,  currently  15  to  3600
              seconds.

       other_config : mcast-snooping-table-size: optional string, containing an integer, at least
       1
              The maximum number of  multicast  snooping  addresses  to  learn.  The  default  is
              currently  2048.  The  value,  if  specified,  is  forced  into a reasonable range,
              currently 10 to 1,000,000.

       other_config : mcast-snooping-disable-flood-unregistered: optional string, either true  or
       false
              If  set to false, unregistered multicast packets are forwarded to all ports. If set
              to true, unregistered  multicast  packets  are  forwarded  to  ports  connected  to
              multicast routers.

     STP Status:

       These  key-value  pairs  report the status of 802.1D-1998. They are present only if STP is
       enabled (via the stp_enable column).

       status : stp_bridge_id: optional string
              The bridge ID used in spanning tree advertisements, in the  form  xxxx.yyyyyyyyyyyy
              where  the  xs are the STP priority, the ys are the STP system ID, and each x and y
              is a hex digit.

       status : stp_designated_root: optional string
              The  designated  root   for   this   spanning   tree,   in   the   same   form   as
              status:stp_bridge_id.  If this bridge is the root, this will have the same value as
              status:stp_bridge_id, otherwise it will differ.

       status : stp_root_path_cost: optional string
              The path cost of reaching the designated bridge. A  lower  number  is  better.  The
              value is 0 if this bridge is the root, otherwise it is higher.

     Rapid Spanning Tree:

       Rapid  Spanning  Tree  Protocol (RSTP), like STP, is a network protocol that ensures loop-
       free topologies. RSTP superseded STP with the publication of 802.1D-2004. Compared to STP,
       RSTP converges more quickly and recovers more quickly from failures.

     RSTP Configuration:

       rstp_enable: boolean
              Enable  Rapid Spanning Tree on the bridge. By default, RSTP is disabled on bridges.
              Bond, internal, and mirror ports are not supported and will not participate in  the
              spanning tree.

              STP and RSTP are mutually exclusive. If both are enabled, RSTP will be used.

       other_config : rstp-address: optional string
              The  bridge’s  RSTP  address  (the  lower  48  bits  of  the bridge-id) in the form
              xx:xx:xx:xx:xx:xx. By default, the address is the MAC address of the bridge.

       other_config : rstp-priority: optional string, containing an integer, in range 0 to 61,440
              The bridge’s relative priority value for determining the root bridge (the upper  16
              bits  of the bridge-id). A bridge with the lowest bridge-id is elected the root. By
              default, the priority is 0x8000 (32768). This value needs to be a multiple of 4096,
              otherwise it’s rounded to the nearest inferior one.

       other_config  :  rstp-ageing-time:  optional string, containing an integer, in range 10 to
       1,000,000
              The Ageing Time parameter for the Bridge. The default value is 300 seconds.

       other_config : rstp-force-protocol-version: optional string, containing an integer
              The Force Protocol Version parameter for the Bridge. This can take the value 0 (STP
              Compatibility mode) or 2 (the default, normal operation).

       other_config : rstp-max-age: optional string, containing an integer, in range 6 to 40
              The  maximum  age  of the information transmitted by the Bridge when it is the Root
              Bridge. The default value is 20.

       other_config : rstp-forward-delay: optional string, containing an integer, in range  4  to
       30
              The  delay  used  by  STP  Bridges  to  transition  Root  and  Designated  Ports to
              Forwarding. The default value is 15.

       other_config : rstp-transmit-hold-count: optional string, containing an integer, in  range
       1 to 10
              The  Transmit  Hold  Count  used  by  the  Port  Transmit  state  machine  to limit
              transmission rate. The default value is 6.

     RSTP Status:

       These key-value pairs report the status of 802.1D-2004. They are present only if  RSTP  is
       enabled (via the rstp_enable column).

       rstp_status : rstp_bridge_id: optional string
              The   bridge   ID   used  in  rapid  spanning  tree  advertisements,  in  the  form
              x.yyy.zzzzzzzzzzzz where x is the RSTP priority, the  ys  are  a  locally  assigned
              system  ID  extension,  the  zs are the STP system ID, and each x, y, or z is a hex
              digit.

       rstp_status : rstp_root_id: optional string
              The root of this spanning tree, in the same form as rstp_status:rstp_bridge_id.  If
              this    bridge    is    the    root,   this   will   have   the   same   value   as
              rstp_status:rstp_bridge_id, otherwise it will differ.

       rstp_status : rstp_root_path_cost: optional string, containing an integer, at least 0
              The path cost of reaching the root. A lower number is better. The  value  is  0  if
              this bridge is the root, otherwise it is higher.

       rstp_status : rstp_designated_id: optional string
              The RSTP designated ID, in the same form as rstp_status:rstp_bridge_id.

       rstp_status : rstp_designated_port_id: optional string
              The RSTP designated port ID, as a 4-digit hex number.

       rstp_status : rstp_bridge_port_id: optional string
              The RSTP bridge port ID, as a 4-digit hex number.

     Multicast Snooping Configuration:

       Multicast  snooping  (RFC 4541) monitors the Internet Group Management Protocol (IGMP) and
       Multicast Listener Discovery traffic between hosts and multicast routers. The switch  uses
       what IGMP and MLD snooping learns to forward multicast traffic only to interfaces that are
       connected to interested receivers. Currently it supports IGMPv1, IGMPv2, IGMPv3, MLDv1 and
       MLDv2 protocols.

       mcast_snooping_enable: boolean
              Enable multicast snooping on the bridge. For now, the default is disabled.

     Other Features:

       datapath_type: string
              Name  of  datapath  provider.  The  kernel  datapath has type system. The userspace
              datapath has type netdev. A manager may refer to the datapath_types column  of  the
              Open_vSwitch table for a list of the types accepted by this Open vSwitch instance.

       external_ids : bridge-id: optional string
              A  unique  identifier  of the bridge. On Citrix XenServer this will commonly be the
              same as external_ids:xs-network-uuids.

       external_ids : xs-network-uuids: optional string
              Semicolon-delimited set of universally unique identifier(s) for  the  network  with
              which this bridge is associated on a Citrix XenServer host. The network identifiers
              are RFC 4122 UUIDs as displayed by, e.g., xe network-list.

       other_config : hwaddr: optional string
              An Ethernet address in the form xx:xx:xx:xx:xx:xx to set the  hardware  address  of
              the local port and influence the datapath ID.

       other_config : forward-bpdu: optional string, either true or false
              Controls forwarding of BPDUs and other network control frames when NORMAL action is
              invoked. When this  option  is  false  or  unset,  frames  with  reserved  Ethernet
              addresses  (see  table below) will not be forwarded. When this option is true, such
              frames will not be treated specially.

              The above general rule has the following exceptions:

              •      If STP is enabled on the bridge (see the stp_enable  column  in  the  Bridge
                     table),  the bridge processes all received STP packets and never passes them
                     to OpenFlow or forwards them. This is true even if STP  is  disabled  on  an
                     individual port.

              •      If  LLDP  is  enabled  on an interface (see the lldp column in the Interface
                     table), the interface processes received LLDP packets and never passes  them
                     to OpenFlow or forwards them.

              Set  this  option  to  true  if the Open vSwitch bridge connects different Ethernet
              networks and is not configured to participate in STP.

              This option affects packets with the following destination MAC addresses:

              01:80:c2:00:00:00
                     IEEE 802.1D Spanning Tree Protocol (STP).

              01:80:c2:00:00:01
                     IEEE Pause frame.

              01:80:c2:00:00:0x
                     Other reserved protocols.

              00:e0:2b:00:00:00
                     Extreme Discovery Protocol (EDP).

              00:e0:2b:00:00:04 and 00:e0:2b:00:00:06
                     Ethernet Automatic Protection Switching (EAPS).

              01:00:0c:cc:cc:cc
                     Cisco Discovery  Protocol  (CDP),  VLAN  Trunking  Protocol  (VTP),  Dynamic
                     Trunking Protocol (DTP), Port Aggregation Protocol (PAgP), and others.

              01:00:0c:cc:cc:cd
                     Cisco Shared Spanning Tree Protocol PVSTP+.

              01:00:0c:cd:cd:cd
                     Cisco STP Uplink Fast.

              01:00:0c:00:00:00
                     Cisco Inter Switch Link.

              01:00:0c:cc:cc:cx
                     Cisco CFM.

       other_config : mac-aging-time: optional string, containing an integer, at least 1
              The  maximum  number of seconds to retain a MAC learning entry for which no packets
              have been seen. The default is currently 300 seconds (5  minutes).  The  value,  if
              specified, is forced into a reasonable range, currently 15 to 3600 seconds.

              A  short  MAC  aging time allows a network to more quickly detect that a host is no
              longer connected to a switch port. However, it  also  makes  it  more  likely  that
              packets  will be flooded unnecessarily, when they are addressed to a connected host
              that rarely transmits packets. To reduce the incidence of unnecessary flooding, use
              a  MAC  aging time longer than the maximum interval at which a host will ordinarily
              transmit packets.

       other_config : mac-table-size: optional string, containing an integer, at least 1
              The maximum number of MAC addresses to learn. The default is  currently  8192.  The
              value, if specified, is forced into a reasonable range, currently 10 to 1,000,000.

     Common Columns:

       The overall purpose of these columns is described under Common Columns at the beginning of
       this document.

       other_config: map of string-string pairs

       external_ids: map of string-string pairs

Port TABLE

       A port within a Bridge.

       Most commonly, a port has exactly one ``interface,’’ pointed to by its interfaces  column.
       Such  a  port  logically  corresponds to a port on a physical Ethernet switch. A port with
       more than one interface is a ``bonded port’’ (see Bonding Configuration).

       Some properties that one might think as belonging to a  port  are  actually  part  of  the
       port’s Interface members.

   Summary:
       name                          immutable string (must be unique within table)
       interfaces                    set of 1 or more Interfaces
       VLAN Configuration:
         vlan_mode                   optional string, one of access, dot1q-tunnel, native-tagged,
                                     native-untagged, or trunk
         tag                         optional integer, in range 0 to 4,095
         trunks                      set of up to 4,096 integers, in range 0 to 4,095
         cvlans                      set of up to 4,096 integers, in range 0 to 4,095
         other_config : qinq-ethtype
                                     optional string, either 802.1ad or 802.1q
         other_config : priority-tags
                                     optional string, one of always, if-nonzero, or never
       Bonding Configuration:
         bond_mode                   optional  string,  one  of  active-backup,  balance-slb,  or
                                     balance-tcp
         other_config : bond-hash-basis
                                     optional string, containing an integer
         Link Failure Detection:
            other_config : bond-detect-mode
                                     optional string, either carrier or miimon
            other_config : bond-miimon-interval
                                     optional string, containing an integer
            bond_updelay             integer
            bond_downdelay           integer
         LACP Configuration:
            lacp                     optional string, one of active, off, or passive
            other_config : lacp-system-id
                                     optional string
            other_config : lacp-system-priority
                                     optional string, containing an integer, in range 1 to 65,535
            other_config : lacp-time optional string, either fast or slow
            other_config : lacp-fallback-ab
                                     optional string, either true or false
         Rebalancing Configuration:
            other_config : bond-rebalance-interval
                                     optional  string,  containing  an  integer,  in  range  0 to
                                     2,147,483,647
         bond_fake_iface             boolean
       Spanning Tree Protocol:
         STP Configuration:
            other_config : stp-enable
                                     optional string, either true or false
            other_config : stp-port-num
                                     optional string, containing an integer, in range 1 to 255
            other_config : stp-port-priority
                                     optional string, containing an integer, in range 0 to 255
            other_config : stp-path-cost
                                     optional string, containing an integer, in range 0 to 65,535
         STP Status:
            status : stp_port_id     optional string
            status : stp_state       optional string,  one  of  blocking,  disabled,  forwarding,
                                     learning, or listening
            status : stp_sec_in_state
                                     optional string, containing an integer, at least 0
            status : stp_role        optional string, one of alternate, designated, or root
       Rapid Spanning Tree Protocol:
         RSTP Configuration:
            other_config : rstp-enable
                                     optional string, either true or false
            other_config : rstp-port-priority
                                     optional string, containing an integer, in range 0 to 240
            other_config : rstp-port-num
                                     optional string, containing an integer, in range 1 to 4,095
            other_config : rstp-port-path-cost
                                     optional string, containing an integer
            other_config : rstp-port-admin-edge
                                     optional string, either true or false
            other_config : rstp-port-auto-edge
                                     optional string, either true or false
            other_config : rstp-port-mcheck
                                     optional string, either true or false
         RSTP Status:
            rstp_status : rstp_port_id
                                     optional string
            rstp_status : rstp_port_role
                                     optional  string,  one  of  Alternate,  Backup,  Designated,
                                     Disabled, or Root
            rstp_status : rstp_port_state
                                     optional string, one of Disabled, Discarding, Forwarding, or
                                     Learning
            rstp_status : rstp_designated_bridge_id
                                     optional string
            rstp_status : rstp_designated_port_id
                                     optional string
            rstp_status : rstp_designated_path_cost
                                     optional string, containing an integer
         RSTP Statistics:
            rstp_statistics : rstp_tx_count
                                     optional integer
            rstp_statistics : rstp_rx_count
                                     optional integer
            rstp_statistics : rstp_error_count
                                     optional integer
            rstp_statistics : rstp_uptime
                                     optional integer
       Multicast Snooping:
         other_config : mcast-snooping-flood
                                     optional string, either true or false
         other_config : mcast-snooping-flood-reports
                                     optional string, either true or false
       Other Features:
         qos                         optional QoS
         mac                         optional string
         fake_bridge                 boolean
         protected                   boolean
         external_ids : fake-bridge-id-*
                                     optional string
         other_config : transient    optional string, either true or false
       bond_active_slave             optional string
       Port Statistics:
         Statistics: STP transmit and receive counters:
            statistics : stp_tx_count
                                     optional integer
            statistics : stp_rx_count
                                     optional integer
            statistics : stp_error_count
                                     optional integer
       Common Columns:
         other_config                map of string-string pairs
         external_ids                map of string-string pairs

   Details:
       name: immutable string (must be unique within table)
              Port  name. For a non-bonded port, this should be the same as its interface’s name.
              Port names must otherwise be unique among  the  names  of  ports,  interfaces,  and
              bridges  on  a  host.  Because  port and interfaces names are usually the same, the
              restrictions on the name column in the Interface  table,  particularly  on  length,
              also  apply  to  port  names.  Refer  to  the documentation for Interface names for
              details.

       interfaces: set of 1 or more Interfaces
              The port’s interfaces. If there is more than one, this is a bonded Port.

     VLAN Configuration:

       In short, a VLAN (short for ``virtual LAN’’) is a way to partition a  single  switch  into
       multiple  switches.  VLANs  can  be confusing, so for an introduction, please refer to the
       question ``What’s a VLAN?’’ in the Open vSwitch FAQ.

       A VLAN is sometimes encoded into a packet using a 802.1Q or 802.1ad VLAN header, but every
       packet  is  part  of  some VLAN whether or not it is encoded in the packet. (A packet that
       appears to have no VLAN is part of VLAN 0, by default.) As a result, it’s useful to  think
       of a VLAN as a metadata property of a packet, separate from how the VLAN is encoded. For a
       given port, this column determines how the encoding of a packet that ingresses or egresses
       the  port  maps  to  the  packet’s  VLAN.  When  a  packet  enters the switch, its VLAN is
       determined based on its setting in this column and its VLAN headers,  if  any,  and  then,
       conceptually,  the VLAN headers are then stripped off. Conversely, when a packet exits the
       switch, its VLAN and the settings in this column determine what VLAN headers, if any,  are
       pushed onto the packet before it egresses the port.

       The  VLAN configuration in this column affects Open vSwitch only when it is doing ``normal
       switching.’’ It does not affect flows set up by an OpenFlow  controller,  outside  of  the
       OpenFlow ``normal action.’’

       Bridge ports support the following types of VLAN configuration:

              trunk  A trunk port carries packets on one or more specified VLANs specified in the
                     trunks column (often, on every VLAN). A packet that  ingresses  on  a  trunk
                     port  is in the VLAN specified in its 802.1Q header, or VLAN 0 if the packet
                     has no 802.1Q header. A packet that egresses through a trunk port will  have
                     an 802.1Q header if it has a nonzero VLAN ID.

                     Any  packet  that ingresses on a trunk port tagged with a VLAN that the port
                     does not trunk is dropped.

              access An access port carries packets on exactly one  VLAN  specified  in  the  tag
                     column. Packets egressing on an access port have no 802.1Q header.

                     Any packet with an 802.1Q header with a nonzero VLAN ID that ingresses on an
                     access port is dropped, regardless of whether the VLAN ID in the  header  is
                     the access port’s VLAN ID.

              native-tagged
                     A  native-tagged  port  resembles  a  trunk  port, with the exception that a
                     packet without an 802.1Q header that ingresses on a native-tagged port is in
                     the ``native VLAN’’ (specified in the tag column).

              native-untagged
                     A  native-untagged  port  resembles a native-tagged port, with the exception
                     that a packet that egresses on a native-untagged port  in  the  native  VLAN
                     will not have an 802.1Q header.

              dot1q-tunnel
                     A dot1q-tunnel port is somewhat like an access port. Like an access port, it
                     carries packets on the single VLAN specified in  the  tag  column  and  this
                     VLAN,  called  the  service  VLAN,  does  not appear in an 802.1Q header for
                     packets that ingress or egress on the port. The main difference lies in  the
                     behavior  when  packets  that  include  a 802.1Q header ingress on the port.
                     Whereas an access port drops such packets, a dot1q-tunnel port treats  these
                     as double-tagged with the outer service VLAN tag and the inner customer VLAN
                     taken from the 802.1Q header. Correspondingly, to  egress  on  the  port,  a
                     packet  outer  VLAN  (or  only  VLAN)  must  be tag, which is removed before
                     egress, which exposes the inner (customer) VLAN if one is present.

                     If cvlans is set, only allows packets in the specified customer VLANs.

       A packet will only egress through bridge ports that carry  the  VLAN  of  the  packet,  as
       described by the rules above.

       vlan_mode:  optional  string, one of access, dot1q-tunnel, native-tagged, native-untagged,
       or trunk
              The VLAN mode of the port, as described above. When this column is empty, a default
              mode is selected as follows:

              •      If  tag  contains  a  value,  the  port is an access port. The trunks column
                     should be empty.

              •      Otherwise, the port is a trunk port. The trunks column value is  honored  if
                     it is present.

       tag: optional integer, in range 0 to 4,095
              For  an  access  port,  the  port’s  implicitly tagged VLAN. For a native-tagged or
              native-untagged port, the port’s native VLAN. Must be empty  if  this  is  a  trunk
              port.

       trunks: set of up to 4,096 integers, in range 0 to 4,095
              For  a trunk, native-tagged, or native-untagged port, the 802.1Q VLAN or VLANs that
              this port trunks; if it is empty, then the port trunks all VLANs. Must be empty  if
              this is an access port.

              A  native-tagged  or native-untagged port always trunks its native VLAN, regardless
              of whether trunks includes that VLAN.

       cvlans: set of up to 4,096 integers, in range 0 to 4,095
              For a dot1q-tunnel port, the customer VLANs that this port  includes.  If  this  is
              empty, the port includes all customer VLANs.

              For other kinds of ports, this setting is ignored.

       other_config : qinq-ethtype: optional string, either 802.1ad or 802.1q
              For  a  dot1q-tunnel  port,  this is the TPID for the service tag, that is, for the
              802.1Q header that contains the service VLAN  ID.  Because  packets  that  actually
              ingress  and  egress  a  dot1q-tunnel  port do not include an 802.1Q header for the
              service VLAN, this does not affect packets on the dot1q-tunnel port itself. Rather,
              it  determines  the service VLAN for a packet that ingresses on a dot1q-tunnel port
              and egresses on a trunk port.

              The value 802.1ad specifies TPID 0x88a8, which is also the default if  the  setting
              is omitted. The value 802.1q specifies TPID 0x8100.

              For other kinds of ports, this setting is ignored.

       other_config : priority-tags: optional string, one of always, if-nonzero, or never
              An  802.1Q  header  contains  two  important pieces of information: a VLAN ID and a
              priority. A frame with a zero VLAN  ID,  called  a  ``priority-tagged’’  frame,  is
              supposed  to  be  treated  the  same way as a frame without an 802.1Q header at all
              (except for the priority).

              However, some network elements ignore any frame that has 802.1Q header at all, even
              when  the  VLAN  ID  is  zero.  Therefore,  by default Open vSwitch does not output
              priority-tagged frames, instead omitting the 802.1Q header entirely if the VLAN  ID
              is zero. Set this key to if-nonzero to enable priority-tagged frames on a port.

              For  if-nonzero  Open vSwitch omits the 802.1Q header on output if both the VLAN ID
              and priority would be zero. Set to always to  retain  the  802.1Q  header  in  such
              frames as well.

              All frames output to native-tagged ports have a nonzero VLAN ID, so this setting is
              not meaningful on native-tagged ports.

     Bonding Configuration:

       A port that has more than one interface is a ``bonded  port.’’  Bonding  allows  for  load
       balancing and fail-over.

       The following types of bonding will work with any kind of upstream switch. On the upstream
       switch, do not configure the interfaces as a bond:

              balance-slb
                     Balances flows among slaves based on source MAC  address  and  output  VLAN,
                     with periodic rebalancing as traffic patterns change.

              active-backup
                     Assigns  all  flows  to  one  slave, failing over to a backup slave when the
                     active slave is disabled. This is the only bonding mode in which  interfaces
                     may be plugged into different upstream switches.

       The  following  modes  require the upstream switch to support 802.3ad with successful LACP
       negotiation. If LACP negotiation fails and  other-config:lacp-fallback-ab  is  true,  then
       active-backup mode is used:

              balance-tcp
                     Balances  flows among slaves based on L3 and L4 protocol information such as
                     IP addresses and TCP/UDP ports.

       These columns apply only to bonded ports. Their values are otherwise ignored.

       bond_mode: optional string, one of active-backup, balance-slb, or balance-tcp
              The type of bonding used for a bonded port. Defaults to active-backup if unset.

       other_config : bond-hash-basis: optional string, containing an integer
              An integer hashed along with flows when choosing output  slaves  in  load  balanced
              bonds.  When  changed,  all  flows  will be assigned different hash values possibly
              causing slave selection decisions to change. Does not affect bonding modes which do
              not employ load balancing such as active-backup.

     Link Failure Detection:

       An  important  part  of  link bonding is detecting that links are down so that they may be
       disabled. These settings determine how Open vSwitch detects link failure.

       other_config : bond-detect-mode: optional string, either carrier or miimon
              The means used to detect  link  failures.  Defaults  to  carrier  which  uses  each
              interface’s carrier to detect failures. When set to miimon, will check for failures
              by polling each interface’s MII.

       other_config : bond-miimon-interval: optional string, containing an integer
              The interval, in milliseconds, between successive attempts to poll each interface’s
              MII. Relevant only when other_config:bond-detect-mode is miimon.

       bond_updelay: integer
              The  number  of milliseconds for which the link must stay up on an interface before
              the  interface  is  considered  to  be  up.  Specify  0  to  enable  the  interface
              immediately.

              This setting is honored only when at least one bonded interface is already enabled.
              When no interfaces are enabled, then the first bond interface to come up is enabled
              immediately.

       bond_downdelay: integer
              The number of milliseconds for which the link must stay down on an interface before
              the interface is considered  to  be  down.  Specify  0  to  disable  the  interface
              immediately.

     LACP Configuration:

       LACP,  the  Link Aggregation Control Protocol, is an IEEE standard that allows switches to
       automatically detect that they are connected by multiple links and aggregate across  those
       links. These settings control LACP behavior.

       lacp: optional string, one of active, off, or passive
              Configures  LACP on this port. LACP allows directly connected switches to negotiate
              which links may be bonded. LACP may be enabled on non-bonded ports for the  benefit
              of any switches they may be connected to. active ports are allowed to initiate LACP
              negotiations. passive  ports  are  allowed  to  participate  in  LACP  negotiations
              initiated  by  a  remote  switch,  but  not  allowed  to initiate such negotiations
              themselves. If LACP is enabled on a port whose  partner  switch  does  not  support
              LACP,  the  bond  will  be disabled, unless other-config:lacp-fallback-ab is set to
              true. Defaults to off if unset.

       other_config : lacp-system-id: optional string
              The LACP system ID of this Port. The system ID of a LACP bond is used  to  identify
              itself  to  its  partners.  Must  be  a nonzero MAC address. Defaults to the bridge
              Ethernet address if unset.

       other_config : lacp-system-priority: optional string, containing an integer, in range 1 to
       65,535
              The  LACP system priority of this Port. In LACP negotiations, link status decisions
              are made by the system with the numerically lower priority.

       other_config : lacp-time: optional string, either fast or slow
              The LACP timing which should be used on this Port. By default slow  is  used.  When
              configured  to  be  fast LACP heartbeats are requested at a rate of once per second
              causing connectivity problems to be detected more quickly. In slow mode, heartbeats
              are requested at a rate of once every 30 seconds.

       other_config : lacp-fallback-ab: optional string, either true or false
              Determines  the  behavior  of  openvswitch bond in LACP mode. If the partner switch
              does not support LACP, setting this option to true allows openvswitch  to  fallback
              to active-backup. If the option is set to false, the bond will be disabled. In both
              the cases, once the partner switch is configured to LACP mode, the  bond  will  use
              LACP.

     Rebalancing Configuration:

       These settings control behavior when a bond is in balance-slb or balance-tcp mode.

       other_config : bond-rebalance-interval: optional string, containing an integer, in range 0
       to 2,147,483,647
              For a load balanced bonded port, the  number  of  milliseconds  between  successive
              attempts  to  rebalance  the bond, that is, to move flows from one interface on the
              bond to another in an attempt to keep usage of each  interface  roughly  equal.  If
              zero,  load  balancing  is  disabled on the bond (link failure still cause flows to
              move). If less than 1000ms, the rebalance interval will be 1000ms.

       bond_fake_iface: boolean
              For a bonded port, whether to create a fake internal interface with the name of the
              port. Use only for compatibility with legacy software that requires this.

     Spanning Tree Protocol:

       The  configuration  here  is  only  meaningful,  and  the  status  is only populated, when
       802.1D-1998 Spanning Tree Protocol is enabled on the port’s  Bridge  with  its  stp_enable
       column.

     STP Configuration:

       other_config : stp-enable: optional string, either true or false
              When  STP  is  enabled on a bridge, it is enabled by default on all of the bridge’s
              ports except bond, internal, and mirror ports (which do not work with STP). If this
              column’s value is false, STP is disabled on the port.

       other_config : stp-port-num: optional string, containing an integer, in range 1 to 255
              The  port  number used for the lower 8 bits of the port-id. By default, the numbers
              will be assigned automatically. If any port’s number is manually  configured  on  a
              bridge, then they must all be.

       other_config  :  stp-port-priority:  optional string, containing an integer, in range 0 to
       255
              The port’s relative priority value for determining the root port (the upper 8  bits
              of  the  port-id).  A port with a lower port-id will be chosen as the root port. By
              default, the priority is 0x80.

       other_config : stp-path-cost: optional string, containing an integer, in range 0 to 65,535
              Spanning tree path cost for the port. A lower number indicates a  faster  link.  By
              default, the cost is based on the maximum speed of the link.

     STP Status:

       status : stp_port_id: optional string
              The  port  ID  used in spanning tree advertisements for this port, as 4 hex digits.
              Configuring the port ID is described in the stp-port-num and stp-port-priority keys
              of the other_config section earlier.

       status  :  stp_state: optional string, one of blocking, disabled, forwarding, learning, or
       listening
              STP state of the port.

       status : stp_sec_in_state: optional string, containing an integer, at least 0
              The amount of time this port has been in the current STP state, in seconds.

       status : stp_role: optional string, one of alternate, designated, or root
              STP role of the port.

     Rapid Spanning Tree Protocol:

       The configuration here is  only  meaningful,  and  the  status  and  statistics  are  only
       populated,  when  802.1D-1998  Spanning Tree Protocol is enabled on the port’s Bridge with
       its stp_enable column.

     RSTP Configuration:

       other_config : rstp-enable: optional string, either true or false
              When RSTP is enabled on a bridge, it is enabled by default on all of  the  bridge’s
              ports  except  bond,  internal,  and mirror ports (which do not work with RSTP). If
              this column’s value is false, RSTP is disabled on the port.

       other_config : rstp-port-priority: optional string, containing an integer, in range  0  to
       240
              The  port’s  relative priority value for determining the root port, in multiples of
              16. By default, the port priority is 0x80 (128). Any value in the lower 4  bits  is
              rounded off. The significant upper 4 bits become the upper 4 bits of the port-id. A
              port with the lowest port-id is elected as the root.

       other_config : rstp-port-num: optional string, containing an integer, in range 1 to 4,095
              The local RSTP port number, used as the lower 12 bits of the  port-id.  By  default
              the  port  numbers  are assigned automatically, and typically may not correspond to
              the OpenFlow port numbers. A port with the lowest port-id is elected as the root.

       other_config : rstp-port-path-cost: optional string, containing an integer
              The port path cost. The Port’s contribution, when it is the Root Port, to the  Root
              Path  Cost for the Bridge. By default the cost is automatically calculated from the
              port’s speed.

       other_config : rstp-port-admin-edge: optional string, either true or false
              The admin edge port parameter for the Port. Default is false.

       other_config : rstp-port-auto-edge: optional string, either true or false
              The auto edge port parameter for the Port. Default is true.

       other_config : rstp-port-mcheck: optional string, either true or false
              The mcheck port parameter for the Port. Default is false. May be set to  force  the
              Port  Protocol  Migration  state  machine  to  transmit RST BPDUs for a MigrateTime
              period, to test whether all STP Bridges on the attached LAN have been  removed  and
              the  Port  can continue to transmit RSTP BPDUs. Setting mcheck has no effect if the
              Bridge is operating in STP Compatibility mode.

              Changing the value from true to false has no effect, but needs to be done  if  this
              behavior  is to be triggered again by subsequently changing the value from false to
              true.

     RSTP Status:

       rstp_status : rstp_port_id: optional string
              The port ID used in spanning tree advertisements for this port, as  4  hex  digits.
              Configuring  the  port  ID is described in the rstp-port-num and rstp-port-priority
              keys of the other_config section earlier.

       rstp_status : rstp_port_role: optional  string,  one  of  Alternate,  Backup,  Designated,
       Disabled, or Root
              RSTP role of the port.

       rstp_status  :  rstp_port_state: optional string, one of Disabled, Discarding, Forwarding,
       or Learning
              RSTP state of the port.

       rstp_status : rstp_designated_bridge_id: optional string
              The   port’s   RSTP   designated   bridge    ID,    in    the    same    form    as
              rstp_status:rstp_bridge_id in the Bridge table.

       rstp_status : rstp_designated_port_id: optional string
              The port’s RSTP designated port ID, as 4 hex digits.

       rstp_status : rstp_designated_path_cost: optional string, containing an integer
              The port’s RSTP designated path cost. Lower is better.

     RSTP Statistics:

       rstp_statistics : rstp_tx_count: optional integer
              Number of RSTP BPDUs transmitted through this port.

       rstp_statistics : rstp_rx_count: optional integer
              Number of valid RSTP BPDUs received by this port.

       rstp_statistics : rstp_error_count: optional integer
              Number of invalid RSTP BPDUs received by this port.

       rstp_statistics : rstp_uptime: optional integer
              The duration covered by the other RSTP statistics, in seconds.

     Multicast Snooping:

       other_config : mcast-snooping-flood: optional string, either true or false
              If set to true, multicast packets (except Reports) are unconditionally forwarded to
              the specific port.

       other_config : mcast-snooping-flood-reports: optional string, either true or false
              If set to true, multicast Reports are unconditionally  forwarded  to  the  specific
              port.

     Other Features:

       qos: optional QoS
              Quality of Service configuration for this port.

       mac: optional string
              The  MAC  address to use for this port for the purpose of choosing the bridge’s MAC
              address. This column does not necessarily reflect the port’s  actual  MAC  address,
              nor will setting it change the port’s actual MAC address.

       fake_bridge: boolean
              Does  this  port  represent a sub-bridge for its tagged VLAN within the Bridge? See
              ovs-vsctl(8) for more information.

       protected: boolean
              The protected ports feature allows certain ports to  be  designated  as  protected.
              Traffic  between  protected  ports  is blocked. Protected ports can send traffic to
              unprotected ports. Unprotected ports can send  traffic  to  any  port.  Default  is
              false.

       external_ids : fake-bridge-id-*: optional string
              External  IDs  for  a  fake  bridge  (see  the  fake_bridge  column) are defined by
              prefixing    a    Bridge    external_ids    key     with     fake-bridge-,     e.g.
              fake-bridge-xs-network-uuids.

       other_config : transient: optional string, either true or false
              If    set    to   true,   the   port   will   be   removed   when   ovs-ctl   start
              --delete-transient-ports is used.

       bond_active_slave: optional string
              For a bonded port, record the mac address of the current active slave.

     Port Statistics:

       Key-value  pairs  that  report  port  statistics.  The  update  period  is  controlled  by
       other_config:stats-update-interval in the Open_vSwitch table.

     Statistics: STP transmit and receive counters:

       statistics : stp_tx_count: optional integer
              Number of STP BPDUs sent on this port by the spanning tree library.

       statistics : stp_rx_count: optional integer
              Number  of  STP  BPDUs  received  on  this  port  and accepted by the spanning tree
              library.

       statistics : stp_error_count: optional integer
              Number of bad STP BPDUs received on this port. Bad BPDUs include runt  packets  and
              those with an unexpected protocol ID.

     Common Columns:

       The overall purpose of these columns is described under Common Columns at the beginning of
       this document.

       other_config: map of string-string pairs

       external_ids: map of string-string pairs

Interface TABLE

       An interface within a Port.

   Summary:
       Core Features:
         name                        immutable string (must be unique within table)
         ifindex                     optional integer, in range 0 to 4,294,967,295
         mac_in_use                  optional string
         mac                         optional string
         error                       optional string
         OpenFlow Port Number:
            ofport                   optional integer
            ofport_request           optional integer, in range 1 to 65,279
       System-Specific Details:
         type                        string
       Tunnel Options:
         options : remote_ip         optional string
         options : local_ip          optional string
         options : in_key            optional string
         options : out_key           optional string
         options : dst_port          optional string
         options : key               optional string
         options : tos               optional string
         options : ttl               optional string
         options : df_default        optional string, either true or false
         options : egress_pkt_mark   optional string
         Tunnel Options: lisp only:
            options : packet_type    optional string, either legacy_l3 or ptap
         Tunnel Options: vxlan only:
            options : exts           optional string
            options : packet_type    optional string, one of legacy_l2, legacy_l3, or ptap
         Tunnel Options: gre only:
            options : packet_type    optional string, one of legacy_l2, legacy_l3, or ptap
            options : seq            optional string, either true or false
         Tunnel Options: gre, ip6gre, geneve, and vxlan:
            options : csum           optional string, either true or false
         Tunnel Options: IPsec:
            options : psk            optional string
            options : remote_cert    optional string
            options : remote_name    optional string
       Tunnel Options: erspan only:
         options : erspan_idx        optional string
         options : erspan_ver        optional string
         options : erspan_dir        optional string
         options : erspan_hwid       optional string
       Patch Options:
         options : peer              optional string
       PMD (Poll Mode Driver) Options:
         options : n_rxq             optional string, containing an integer, at least 1
         options : dpdk-devargs      optional string
         other_config : pmd-rxq-affinity
                                     optional string
         options : xdp-mode          optional    string,    one    of    best-effort,    generic,
                                     native-with-zerocopy, or native
         options : use-need-wakeup   optional string, either true or false
         options : vhost-server-path
                                     optional string
         options : dq-zero-copy      optional string, either true or false
         options : tx-retries-max    optional string, containing an integer, in range 0 to 32
         options : n_rxq_desc        optional string, containing an integer, in range 1 to 4,096
         options : n_txq_desc        optional string, containing an integer, in range 1 to 4,096
       EMC (Exact Match Cache) Configuration:
         other_config : emc-enable   optional string, either true or false
       MTU:
         mtu                         optional integer
         mtu_request                 optional integer, at least 1
       Interface Status:
         admin_state                 optional string, either down or up
         link_state                  optional string, either down or up
         link_resets                 optional integer
         link_speed                  optional integer
         duplex                      optional string, either full or half
         lacp_current                optional boolean
         status                      map of string-string pairs
         status : driver_name        optional string
         status : driver_version     optional string
         status : firmware_version   optional string
         status : source_ip          optional string
         status : tunnel_egress_iface
                                     optional string
         status : tunnel_egress_iface_carrier
                                     optional string, either down or up
         dpdk:
            status : port_no         optional string
            status : numa_id         optional string
            status : min_rx_bufsize  optional string
            status : max_rx_pktlen   optional string
            status : max_rx_queues   optional string
            status : max_tx_queues   optional string
            status : max_mac_addrs   optional string
            status : max_hash_mac_addrs
                                     optional string
            status : max_vfs         optional string
            status : max_vmdq_pools  optional string
            status : if_type         optional string
            status : if_descr        optional string
            status : pci-vendor_id   optional string
            status : pci-device_id   optional string
       Statistics:
         Statistics: Successful transmit and receive counters:
            statistics : rx_packets  optional integer
            statistics : rx_bytes    optional integer
            statistics : tx_packets  optional integer
            statistics : tx_bytes    optional integer
         Statistics: Receive errors:
            statistics : rx_dropped  optional integer
            statistics : rx_frame_err
                                     optional integer
            statistics : rx_over_err optional integer
            statistics : rx_crc_err  optional integer
            statistics : rx_errors   optional integer
         Statistics: Transmit errors:
            statistics : tx_dropped  optional integer
            statistics : collisions  optional integer
            statistics : tx_errors   optional integer
       Ingress Policing:
         ingress_policing_rate       integer, at least 0
         ingress_policing_burst      integer, at least 0
       Bidirectional Forwarding Detection (BFD):
         BFD Configuration:
            bfd : enable             optional string, either true or false
            bfd : min_rx             optional string, containing an integer, at least 1
            bfd : min_tx             optional string, containing an integer, at least 1
            bfd : decay_min_rx       optional string, containing an integer
            bfd : forwarding_if_rx   optional string, either true or false
            bfd : cpath_down         optional string, either true or false
            bfd : check_tnl_key      optional string, either true or false
            bfd : bfd_local_src_mac  optional string
            bfd : bfd_local_dst_mac  optional string
            bfd : bfd_remote_dst_mac optional string
            bfd : bfd_src_ip         optional string
            bfd : bfd_dst_ip         optional string
            bfd : oam                optional string
            bfd : mult               optional string, containing an integer, in range 1 to 255
         BFD Status:
            bfd_status : state       optional string, one of admin_down, down, init, or up
            bfd_status : forwarding  optional string, either true or false
            bfd_status : diagnostic  optional string
            bfd_status : remote_state
                                     optional string, one of admin_down, down, init, or up
            bfd_status : remote_diagnostic
                                     optional string
            bfd_status : flap_count  optional string, containing an integer, at least 0
       Connectivity Fault Management:
         cfm_mpid                    optional integer
         cfm_flap_count              optional integer
         cfm_fault                   optional boolean
         cfm_fault_status : recv     none
         cfm_fault_status : rdi      none
         cfm_fault_status : maid     none
         cfm_fault_status : loopback
                                     none
         cfm_fault_status : overflow
                                     none
         cfm_fault_status : override
                                     none
         cfm_fault_status : interval
                                     none
         cfm_remote_opstate          optional string, either down or up
         cfm_health                  optional integer, in range 0 to 100
         cfm_remote_mpids            set of integers
         other_config : cfm_interval
                                     optional string, containing an integer
         other_config : cfm_extended
                                     optional string, either true or false
         other_config : cfm_demand   optional string, either true or false
         other_config : cfm_opstate  optional string, either down or up
         other_config : cfm_ccm_vlan
                                     optional string, containing an integer, in range 1 to 4,095
         other_config : cfm_ccm_pcp  optional string, containing an integer, in range 1 to 7
       Bonding Configuration:
         other_config : lacp-port-id
                                     optional string, containing an integer, in range 1 to 65,535
         other_config : lacp-port-priority
                                     optional string, containing an integer, in range 1 to 65,535
         other_config : lacp-aggregation-key
                                     optional string, containing an integer, in range 1 to 65,535
       Virtual Machine Identifiers:
         external_ids : attached-mac
                                     optional string
         external_ids : iface-id     optional string
         external_ids : iface-status
                                     optional string, either active or inactive
         external_ids : xs-vif-uuid  optional string
         external_ids : xs-network-uuid
                                     optional string
         external_ids : vm-id        optional string
         external_ids : xs-vm-uuid   optional string
       Auto Attach Configuration:
         lldp : enable               optional string, either true or false
       Flow control Configuration:
         options : rx-flow-ctrl      optional string, either true or false
         options : tx-flow-ctrl      optional string, either true or false
         options : flow-ctrl-autoneg
                                     optional string, either true or false
       Link State Change detection mode:
         options : dpdk-lsc-interrupt
                                     optional string, either true or false
       Common Columns:
         other_config                map of string-string pairs
         external_ids                map of string-string pairs

   Details:
     Core Features:

       name: immutable string (must be unique within table)
              Interface  name.  Should  be  alphanumeric. For non-bonded port, this should be the
              same as the port name. It must otherwise  be  unique  among  the  names  of  ports,
              interfaces, and bridges on a host.

              The maximum length of an interface name depends on the underlying datapath:

              •      The  names  of  interfaces  implemented  as  Linux  and BSD network devices,
                     including interfaces with type internal, tap, or system plus  the  different
                     types  of  tunnel ports, are limited to 15 bytes. Windows limits these names
                     to 255 bytes.

              •      The names of patch ports  are  not  used  in  the  underlying  datapath,  so
                     operating  system  restrictions  do not apply. Thus, they may have arbitrary
                     length.

              Regardless of other restrictions, OpenFlow only supports 15-byte names, which means
              that ovs-ofctl and OpenFlow controllers will show names truncated to 15 bytes.

       ifindex: optional integer, in range 0 to 4,294,967,295
              A positive interface index as defined for SNMP MIB-II in RFCs 1213 and 2863, if the
              interface has one, otherwise 0. The ifindex is useful for seamless integration with
              protocols such as SNMP and sFlow.

       mac_in_use: optional string
              The MAC address in use by this interface.

       mac: optional string
              Ethernet  address  to set for this interface. If unset then the default MAC address
              is used:

              •      For the local interface, the default  is  the  lowest-numbered  MAC  address
                     among  the  other  bridge  ports,  either  the  value of the mac in its Port
                     record, if set, or its actual MAC (for bonded ports, the MAC  of  its  slave
                     whose  name is first in alphabetical order). Internal ports and bridge ports
                     that are used as port mirroring destinations  (see  the  Mirror  table)  are
                     ignored.

              •      For other internal interfaces, the default MAC is randomly generated.

              •      External  interfaces  typically  have  a  MAC  address associated with their
                     hardware.

              Some interfaces may not have a software-controllable MAC address. This option  only
              affects  internal  ports.  For  other  type  ports,  you can change the MAC address
              outside Open vSwitch, using ip command.

       error: optional string
              If the configuration of the port failed, as indicated by -1 in ofport, Open vSwitch
              sets  this  column  to an error description in human readable form. Otherwise, Open
              vSwitch clears this column.

     OpenFlow Port Number:

       When a client adds a new interface, Open vSwitch chooses an OpenFlow port number  for  the
       new  port.  If  the  client  that adds the port fills in ofport_request, then Open vSwitch
       tries to use its value as the OpenFlow port number. Otherwise, or if  the  requested  port
       number  is already in use or cannot be used for another reason, Open vSwitch automatically
       assigns a free port number. Regardless of how the port number was obtained,  Open  vSwitch
       then reports in ofport the port number actually assigned.

       Open  vSwitch limits the port numbers that it automatically assigns to the range 1 through
       32,767, inclusive. Controllers therefore have free use of ports 32,768 and up.

       ofport: optional integer
              OpenFlow port number for this interface. Open vSwitch sets this column’s value,  so
              other clients should treat it as read-only.

              The  OpenFlow  ``local’’  port (OFPP_LOCAL) is 65,534. The other valid port numbers
              are in the range 1 to 65,279, inclusive. Value -1 indicates  an  error  adding  the
              interface.

       ofport_request: optional integer, in range 1 to 65,279
              Requested OpenFlow port number for this interface.

              A  client  should  ideally set this column’s value in the same database transaction
              that it uses to create the interface. Open vSwitch version 2.1 and later will honor
              a  later  request  for  a  specific  port  number,  althuogh  it might confuse some
              controllers: OpenFlow does not have a way to announce a port number change, so Open
              vSwitch  represents  it  over OpenFlow as a port deletion followed immediately by a
              port addition.

              If ofport_request is set or changed to some  other  port’s  automatically  assigned
              port number, Open vSwitch chooses a new port number for the latter port.

     System-Specific Details:

       type: string
              The  interface  type.  The types supported by a particular instance of Open vSwitch
              are listed in the iface_types column in the Open_vSwitch table. The following types
              are defined:

              system An  ordinary  network  device,  e.g. eth0 on Linux. Sometimes referred to as
                     ``external interfaces’’ since  they  are  generally  connected  to  hardware
                     external to that on which the Open vSwitch is running. The empty string is a
                     synonym for system.

              internal
                     A simulated network device that sends  and  receives  traffic.  An  internal
                     interface  whose name is the same as its bridge’s name is called the ``local
                     interface.’’ It does not make sense to bond an internal  interface,  so  the
                     terms  ``port’’  and  ``interface’’  are often used imprecisely for internal
                     interfaces.

              tap    A TUN/TAP device managed by Open vSwitch.

                     Open vSwitch checks the interface state before send packets to  the  device.
                     When  it  is  down,  the packets are dropped and the tx_dropped statistic is
                     updated accordingly. Older versions  of  Open  vSwitch  did  not  check  the
                     interface   state  and  then  the  tx_packets  was  incremented  along  with
                     tx_dropped.

              geneve An Ethernet over Geneve  (http://tools.ietf.org/html/draft-ietf-nvo3-geneve)
                     IPv4/IPv6  tunnel.  A description of how to match and set Geneve options can
                     be found in the ovs-ofctl manual page.

              gre    Generic Routing  Encapsulation  (GRE)  over  IPv4  tunnel,  configurable  to
                     encapsulate layer 2 or layer 3 traffic.

              ip6gre Generic  Routing  Encapsulation  (GRE) over IPv6 tunnel, encapsulate layer 2
                     traffic.

              vxlan  An Ethernet tunnel over the UDP-based VXLAN protocol described in RFC 7348.

                     Open vSwitch uses IANA-assigned UDP destination port 4789. The  source  port
                     used  for  VXLAN  traffic varies on a per-flow basis and is in the ephemeral
                     port range.

              lisp   A layer 3 tunnel over  the  experimental,  UDP-based  Locator/ID  Separation
                     Protocol (RFC 6830).

                     Only  IPv4 and IPv6 packets are supported by the protocol, and they are sent
                     and received without an Ethernet  header.  Traffic  to/from  LISP  ports  is
                     expected  to  be  configured  explicitly,  and the ports are not intended to
                     participate in learning based switching. As such, they are  always  excluded
                     from packet flooding.

              stt    The  Stateless TCP Tunnel (STT) is particularly useful when tunnel endpoints
                     are in end-systems, as it utilizes  the  capabilities  of  standard  network
                     interface  cards  to  improve  performance.  STT  utilizes a TCP-like header
                     inside the IP header. It is stateless, i.e.,  there  is  no  TCP  connection
                     state of any kind associated with the tunnel. The TCP-like header is used to
                     leverage the capabilities of existing network interface  cards,  but  should
                     not  be  interpreted  as  implying  any  sort  of  connection  state between
                     endpoints. Since the STT protocol does not engage in  the  usual  TCP  3-way
                     handshake,  so  it  will  have difficulty traversing stateful firewalls. The
                     protocol is documented  at  https://tools.ietf.org/html/draft-davie-stt  All
                     traffic uses a default destination port of 7471.

              patch  A pair of virtual devices that act as a patch cable.

     Tunnel Options:

       These options apply to interfaces with type of geneve, gre, ip6gre, vxlan, lisp and stt.

       Each  tunnel  must  be  uniquely identified by the combination of type, options:remote_ip,
       options:local_ip, and options:in_key. If two ports are defined that are  the  same  except
       one  has  an  optional identifier and the other does not, the more specific one is matched
       first. options:in_key is considered more specific than options:local_ip if a port  defines
       one and another port defines the other.

       options : remote_ip: optional string
              Required. The remote tunnel endpoint, one of:

              •      An  IPv4  or IPv6 address (not a DNS name), e.g. 192.168.0.123. Only unicast
                     endpoints are supported.

              •      The word flow. The tunnel accepts packets from any remote  tunnel  endpoint.
                     To  process  only  packets  from a specific remote tunnel endpoint, the flow
                     entries may match on the tun_src or tun_ipv6_srcfield. When sending  packets
                     to a remote_ip=flow tunnel, the flow actions must explicitly set the tun_dst
                     or tun_ipv6_dst field to  the  IP  address  of  the  desired  remote  tunnel
                     endpoint, e.g. with a set_field action.

              The  remote  tunnel  endpoint for any packet received from a tunnel is available in
              the tun_src field for matching in the flow table.

       options : local_ip: optional string
              Optional. The tunnel destination IP that received packets must match. Default is to
              match all addresses. If specified, may be one of:

              •      An IPv4/IPv6 address (not a DNS name), e.g. 192.168.12.3.

              •      The  word  flow.  The  tunnel  accepts  packets  sent to any of the local IP
                     addresses of the system running OVS. To  process  only  packets  sent  to  a
                     specific  IP  address,  the  flow  entries  may  match  on  the  tun_dst  or
                     tun_ipv6_dst field. When sending packets to a local_ip=flow tunnel, the flow
                     actions  may explicitly set the tun_src or tun_ipv6_src field to the desired
                     IP address, e.g.  with  a  set_field  action.  However,  while  routing  the
                     tunneled  packet  out,  the  local system may override the specified address
                     with the local IP address configured for the outgoing system interface.

                     This  option  is  valid  only  for  tunnels   also   configured   with   the
                     remote_ip=flow option.

              The  tunnel  destination  IP  address  for  any  packet  received  from a tunnel is
              available in the tun_dst or tun_ipv6_dst field for matching in the flow table.

       options : in_key: optional string
              Optional. The key that received packets must contain, one of:

              •      0. The tunnel receives packets with no key or with  a  key  of  0.  This  is
                     equivalent to specifying no options:in_key at all.

              •      A  positive 24-bit (for Geneve, VXLAN, and LISP), 32-bit (for GRE) or 64-bit
                     (for STT) number. The tunnel receives only packets with the specified key.

              •      The word flow. The tunnel accepts packets with any  key.  The  key  will  be
                     placed in the tun_id field for matching in the flow table. The ovs-fields(7)
                     manual  page  contains  additional  information  about  matching  fields  in
                     OpenFlow flows.

       options : out_key: optional string
              Optional. The key to be set on outgoing packets, one of:

              •      0.  Packets  sent through the tunnel will have no key. This is equivalent to
                     specifying no options:out_key at all.

              •      A positive 24-bit (for Geneve, VXLAN and LISP), 32-bit (for GRE)  or  64-bit
                     (for  STT)  number.  Packets sent through the tunnel will have the specified
                     key.

              •      The word flow. Packets sent through the tunnel will have the key  set  using
                     the set_tunnel Nicira OpenFlow vendor extension (0 is used in the absence of
                     an action). The ovs-fields(7) manual page  contains  additional  information
                     about the Nicira OpenFlow vendor extensions.

       options : dst_port: optional string
              Optional. The tunnel transport layer destination port, for UDP and TCP based tunnel
              protocols (Geneve, VXLAN, LISP, and STT).

       options : key: optional string
              Optional. Shorthand to set in_key and out_key at the same time.

       options : tos: optional string
              Optional. The value of the ToS bits to be set on the encapsulating packet.  ToS  is
              interpreted  as  DSCP  and ECN bits, ECN part must be zero. It may also be the word
              inherit, in which case the ToS will be copied from the inner packet if it  is  IPv4
              or  IPv6  (otherwise it will be 0). The ECN fields are always inherited. Default is
              0.

       options : ttl: optional string
              Optional. The TTL to be set on the encapsulating packet. It may also  be  the  word
              inherit,  in  which case the TTL will be copied from the inner packet if it is IPv4
              or IPv6 (otherwise it will be the system default, typically  64).  Default  is  the
              system default TTL.

       options : df_default: optional string, either true or false
              Optional. If enabled, the Don’t Fragment bit will be set on tunnel outer headers to
              allow path MTU discovery. Default is enabled; set to false to disable.

       options : egress_pkt_mark: optional string
              Optional. The pkt_mark to be set on the  encapsulating  packet.  This  option  sets
              packet  mark  for  the  tunnel  endpoint  for  all  tunnel packets including tunnel
              monitoring.

     Tunnel Options: lisp only:

       options : packet_type: optional string, either legacy_l3 or ptap
              A LISP tunnel sends and receives only IPv4 and IPv6 packets. This  option  controls
              what how the tunnel represents the packets that it sends and receives:

              •      By default, or if this option is legacy_l3, the tunnel represents packets as
                     Ethernet frames for compatibility  with  legacy  OpenFlow  controllers  that
                     expect this behavior.

              •      If  this option is ptap, the tunnel represents packets using the packet_type
                     mechanism introduced in OpenFlow 1.5.

     Tunnel Options: vxlan only:

       options : exts: optional string
              Optional. Comma  separated  list  of  optional  VXLAN  extensions  to  enable.  The
              following extensions are supported:

              •      gbp:  VXLAN-GBP  allows  to  transport  the group policy context of a packet
                     across the VXLAN tunnel to other  network  peers.  See  the  description  of
                     tun_gbp_id  and  tun_gbp_flags  in ovs-fields(7) for additional information.
                     (https://tools.ietf.org/html/draft-smith-vxlan-group-policy)

              •      gpe: Support for Generic Protocol  Encapsulation  in  accordance  with  IETF
                     draft  https://tools.ietf.org/html/draft-ietf-nvo3-vxlan-gpe.  Without  this
                     option, a VXLAN packet always encapsulates  an  Ethernet  frame.  With  this
                     option,  an  VXLAN  packet  may also encapsulate an IPv4, IPv6, NSH, or MPLS
                     packet.

       options : packet_type: optional string, one of legacy_l2, legacy_l3, or ptap
              This option controls what types of packets the tunnel sends and receives and how it
              represents them:

              •      By  default,  or  if this option is legacy_l2, the tunnel sends and receives
                     only Ethernet frames.

              •      If this option is legacy_l3, the tunnel sends and receives only non-Ethernet
                     (L3)  packet,  but  the  packets  are  represented  as  Ethernet  frames for
                     compatibility with legacy OpenFlow controllers that  expect  this  behavior.
                     This requires enabling gpe in options:exts.

              •      If  this option is ptap, Open vSwitch represents packets in the tunnel using
                     the  packet_type  mechanism  introduced  in  OpenFlow  1.5.  This  mechanism
                     supports any kind of packet, but actually sending and receiving non-Ethernet
                     packets requires additionally enabling gpe in options:exts.

     Tunnel Options: gre only:

       gre interfaces support these options.

       options : packet_type: optional string, one of legacy_l2, legacy_l3, or ptap
              This option controls what types of packets the tunnel sends and receives and how it
              represents them:

              •      By  default,  or  if this option is legacy_l2, the tunnel sends and receives
                     only Ethernet frames.

              •      If this option is legacy_l3, the tunnel sends and receives only non-Ethernet
                     (L3)  packet,  but  the  packets  are  represented  as  Ethernet  frames for
                     compatibility with legacy OpenFlow controllers that expect this behavior.

              •      The legacy_l3 option is only available via the user space datapath. The  OVS
                     kernel  datapath  does not support devices of type ARPHRD_IPGRE which is the
                     requirement for legacy_l3 type packets.

              •      If this option is ptap, the tunnel sends and receives any  kind  of  packet.
                     Open  vSwitch  represents  packets  in  the  tunnel  using  the  packet_type
                     mechanism introduced in OpenFlow 1.5.

       options : seq: optional string, either true or false
              Optional. A 4-byte sequence number field for GRE tunnel only. Default is  disabled,
              set  to  true  to  enable.  Sequence  number is incremented by one on each outgoing
              packet.

     Tunnel Options: gre, ip6gre, geneve, and vxlan:

       gre, ip6gre, geneve, and vxlan interfaces support these options.

       options : csum: optional string, either true or false
              Optional. Compute encapsulation header (either GRE or UDP)  checksums  on  outgoing
              packets.  Default is disabled, set to true to enable. Checksums present on incoming
              packets will be validated regardless of this setting.

              When using the upstream Linux kernel module, computation of  checksums  for  geneve
              and  vxlan  requires  Linux  kernel  version  4.0 or higher. gre and ip6gre support
              checksums for all versions of Open vSwitch that support GRE. The out of tree kernel
              module  distributed  as  part of OVS can compute all tunnel checksums on any kernel
              version that it is compatible with.

     Tunnel Options: IPsec:

       Setting any of these options enables IPsec support for a given tunnel. gre, geneve,  vxlan
       and  stt interfaces support these options. See the IPsec section in the Open_vSwitch table
       for a description of each mode.

       options : psk: optional string
              In PSK mode only, the preshared secret to negotiate tunnel. This value  must  match
              on both tunnel ends.

       options : remote_cert: optional string
              In  self-signed  certificate mode only, name of a PEM file containing a certificate
              of the remote switch. The certificate must be x.509 version 3 and with  the  string
              in common name (CN) also set in the subject alternative name (SAN).

       options : remote_name: optional string
              In CA-signed certificate mode only, common name (CN) of the remote certificate.

     Tunnel Options: erspan only:

       Only erspan interfaces support these options.

       options : erspan_idx: optional string
              20  bit  index/port  number  associated  with  the ERSPAN traffic’s source port and
              direction (ingress/egress). This field is platform dependent.

       options : erspan_ver: optional string
              ERSPAN version: 1 for version 1 (type II) or 2 for version 2 (type III).

       options : erspan_dir: optional string
              Specifies the ERSPAN v2 mirrored traffic’s direction. 1 for egress traffic,  and  0
              for ingress traffic.

       options : erspan_hwid: optional string
              ERSPAN  hardware  ID  is  a 6-bit unique identifier of an ERSPAN v2 engine within a
              system.

     Patch Options:

       These options apply only to patch ports, that is, interfaces whose type column  is  patch.
       Patch  ports  are  mainly  a  way to connect otherwise independent bridges to one another,
       similar to how one might plug an Ethernet cable (a  ``patch  cable’’)  into  two  physical
       switches  to connect those switches. The effect of plugging a patch port into two switches
       is conceptually similar to that of plugging the two ends of a Linux veth device into those
       switches, but the implementation of patch ports makes them much more efficient.

       Patch  ports may connect two different bridges (the usual case) or the same bridge. In the
       latter case, take special care to avoid loops, e.g. by programming appropriate flows  with
       OpenFlow.  Patch  ports  do  not  work  if  its  ends are attached to bridges on different
       datapaths, e.g. to connect bridges in system and netdev datapaths.

       The following command creates and connects patch ports p0 and p1 and adds them to  bridges
       br0 and br1, respectively:

       ovs-vsctl add-port br0 p0 -- set Interface p0 type=patch options:peer=p1 \
              -- add-port br1 p1 -- set Interface p1 type=patch options:peer=p0

       options : peer: optional string
              The  name  of  the Interface for the other side of the patch. The named Interface’s
              own peer option must  specify  this  Interface’s  name.  That  is,  the  two  patch
              interfaces must have reversed name and peer values.

     PMD (Poll Mode Driver) Options:

       Only PMD netdevs support these options.

       options : n_rxq: optional string, containing an integer, at least 1
              Specifies  the  maximum  number  of  rx queues to be created for PMD netdev. If not
              specified or specified to 0, one rx queue will be created by default. Not supported
              by DPDK vHost interfaces.

       options : dpdk-devargs: optional string
              Specifies  the  PCI  address  associated with the port for physical devices, or the
              virtual driver to be used for the port when a virtual PMD is intended to  be  used.
              For  the  latter, the argument string typically takes the form of eth_driver_namex,
              where driver_name is a valid virtual DPDK  PMD  driver  name  and  x  is  a  unique
              identifier of your choice for the given port. Only supported by the dpdk port type.

       other_config : pmd-rxq-affinity: optional string
              Specifies mapping of RX queues of this interface to CPU cores.

              Value should be set in the following form:

              other_config:pmd-rxq-affinity=<rxq-affinity-list>

              where

              •      <rxq-affinity-list> ::= NULL | <non-empty-list>

              •      <non-empty-list> ::= <affinity-pair> | <affinity-pair> , <non-empty-list>

              •      <affinity-pair> ::= <queue-id> : <core-id>

       options : xdp-mode: optional string, one of best-effort, generic, native-with-zerocopy, or
       native
              Specifies the operational mode of the XDP program.

              In native-with-zerocopy mode the XDP program is loaded into the device driver  with
              zero-copy  RX  and TX enabled. This mode requires device driver support and has the
              best performance because there should be no copying of packets.

              native is the same as native-with-zerocopy, but without zero-copy capability.  This
              requires  at  least  one  copy  between  kernel  and  the userspace. This mode also
              requires support from device driver.

              In generic case the XDP program in kernel  works  after  skb  allocation  on  early
              stages  of  packet  processing  inside the network stack. This mode doesn’t require
              driver support, but has much lower performance.

              best-effort tries to detect and choose the best (fastest) from the available  modes
              for current interface.

              Note that this option is specific to netdev-afxdp. Defaults to best-effort mode.

       options : use-need-wakeup: optional string, either true or false
              Specifies  whether  to  use  need_wakeup  feature  in afxdp netdev. If enabled, OVS
              explicitly wakes up the kernel RX, using poll() syscall  and  wakes  up  TX,  using
              sendto()  syscall.  For  physical devices, this feature improves the performance by
              avoiding unnecessary sendto syscalls. Defaults to true if supported by libbpf.

       options : vhost-server-path: optional string
              The value specifies the path to the socket associated with a vHost User client mode
              device   that   has   been   or   will  be  created  by  QEMU.  Only  supported  by
              dpdkvhostuserclient interfaces.

       options : dq-zero-copy: optional string, either true or false
              The value specifies whether or not  to  enable  dequeue  zero  copy  on  the  given
              interface.  Must  be  set  before vhost-server-path is specified. Only supported by
              dpdkvhostuserclient interfaces. The feature is considered experimental.

       options : tx-retries-max: optional string, containing an integer, in range 0 to 32
              The value specifies the maximum amount of vhost tx retries that can be  made  while
              trying   to   send   a  batch  of  packets  to  an  interface.  Only  supported  by
              dpdkvhostuserclient interfaces.

              Default value is 8.

       options : n_rxq_desc: optional string, containing an integer, in range 1 to 4,096
              Specifies the rx queue size (number rx descriptors) for dpdk ports. The value  must
              be  a  power of 2, less than 4096 and supported by the hardware of the device being
              configured.  If  not  specified  or  an  incorrect  value  is  specified,  2048  rx
              descriptors will be used by default.

       options : n_txq_desc: optional string, containing an integer, in range 1 to 4,096
              Specifies  the tx queue size (number tx descriptors) for dpdk ports. The value must
              be a power of 2, less than 4096 and supported by the hardware of the  device  being
              configured.  If  not  specified  or  an  incorrect  value  is  specified,  2048  tx
              descriptors will be used by default.

     EMC (Exact Match Cache) Configuration:

       These settings controls behaviour of EMC lookups/insertions for packets received from  the
       interface.

       other_config : emc-enable: optional string, either true or false
              Specifies  if  Exact  Match  Cache  (EMC)  should  be used while processing packets
              received from this interface. If true, other_config:emc-insert-inv-prob  will  have
              effect on this interface.

              Defaults to true.

     MTU:

       The  MTU  (maximum  transmission  unit)  is the largest amount of data that can fit into a
       single Ethernet frame. The standard Ethernet MTU is 1500 bytes. Some  physical  media  and
       many kinds of virtual interfaces can be configured with higher MTUs.

       A  client may change an interface MTU by filling in mtu_request. Open vSwitch then reports
       in mtu the currently configured value.

       mtu: optional integer
              The currently configured MTU for the interface.

              This column will be empty for an interface that  does  not  have  an  MTU  as,  for
              example, some kinds of tunnels do not.

              Open  vSwitch  sets  this column’s value, so other clients should treat it as read-
              only.

       mtu_request: optional integer, at least 1
              Requested MTU (Maximum Transmission Unit) for the interface. A client can fill this
              column to change the MTU of an interface.

              RFC  791  requires  every  internet  module  to be able to forward a datagram of 68
              octets without further fragmentation. The maximum size of an  IP  packet  is  65535
              bytes.

              If this is not set and if the interface has internal type, Open vSwitch will change
              the MTU to match the minimum of the other interfaces in the bridge.

     Interface Status:

       Status information about interfaces attached to bridges, updated every 5 seconds. Not  all
       interfaces  have  all of these properties; virtual interfaces don’t have a link speed, for
       example. Non-applicable columns will have empty values.

       admin_state: optional string, either down or up
              The administrative state of the physical network link.

       link_state: optional string, either down or up
              The observed state of the physical network link.  This  is  ordinarily  the  link’s
              carrier status. If the interface’s Port is a bond configured for miimon monitoring,
              it is instead the network link’s miimon status.

       link_resets: optional integer
              The number of times Open vSwitch has observed  the  link_state  of  this  Interface
              change.

       link_speed: optional integer
              The  negotiated  speed  of  the  physical  network  link. Valid values are positive
              integers greater than 0.

       duplex: optional string, either full or half
              The duplex mode of the physical network link.

       lacp_current: optional boolean
              Boolean value indicating LACP status for this interface. If  true,  this  interface
              has  current  LACP information about its LACP partner. This information may be used
              to monitor the health of interfaces in a LACP enabled port.  This  column  will  be
              empty if LACP is not enabled.

       status: map of string-string pairs
              Key-value  pairs  that  report  port  status.  Supported  status  values  are type-
              dependent; some interfaces may not have a valid status:driver_name, for example.

       status : driver_name: optional string
              The name of the device driver controlling the network adapter.

       status : driver_version: optional string
              The version string of the device driver controlling the network adapter.

       status : firmware_version: optional string
              The version string of the network adapter’s firmware, if available.

       status : source_ip: optional string
              The source IP address used for an IPv4/IPv6 tunnel end-point, such as gre.

       status : tunnel_egress_iface: optional string
              Egress interface for tunnels. Currently only relevant for tunnels on Linux systems,
              this  column  will  show the name of the interface which is responsible for routing
              traffic destined for the configured options:remote_ip. This could  be  an  internal
              interface such as a bridge port.

       status : tunnel_egress_iface_carrier: optional string, either down or up
              Whether carrier is detected on status:tunnel_egress_iface.

     dpdk:

       DPDK specific interface status options.

       status : port_no: optional string
              DPDK port ID.

       status : numa_id: optional string
              NUMA socket ID to which an Ethernet device is connected.

       status : min_rx_bufsize: optional string
              Minimum size of RX buffer.

       status : max_rx_pktlen: optional string
              Maximum configurable length of RX pkt.

       status : max_rx_queues: optional string
              Maximum number of RX queues.

       status : max_tx_queues: optional string
              Maximum number of TX queues.

       status : max_mac_addrs: optional string
              Maximum number of MAC addresses.

       status : max_hash_mac_addrs: optional string
              Maximum number of hash MAC addresses for MTA and UTA.

       status : max_vfs: optional string
              Maximum number of hash MAC addresses for MTA and UTA. Maximum number of VFs.

       status : max_vmdq_pools: optional string
              Maximum number of VMDq pools.

       status : if_type: optional string
              Interface type ID according to IANA ifTYPE MIB definitions.

       status : if_descr: optional string
              Interface description string.

       status : pci-vendor_id: optional string
              Vendor ID of PCI device.

       status : pci-device_id: optional string
              Device ID of PCI device.

     Statistics:

       Key-value pairs that report interface statistics. The current implementation updates these
       counters periodically. The  update  period  is  controlled  by  other_config:stats-update-
       interval  in  the  Open_vSwitch  table.  Future  implementations  may  update them when an
       interface is created, when they are queried (e.g. using an OVSDB  select  operation),  and
       just  before  an  interface is deleted due to virtual interface hot-unplug or VM shutdown,
       and perhaps at other times, but not on any regular periodic basis.

       These are the same statistics reported by OpenFlow in its struct ofp_port_stats structure.
       If an interface does not support a given statistic, then that pair is omitted.

     Statistics: Successful transmit and receive counters:

       statistics : rx_packets: optional integer
              Number of received packets.

       statistics : rx_bytes: optional integer
              Number of received bytes.

       statistics : tx_packets: optional integer
              Number of transmitted packets.

       statistics : tx_bytes: optional integer
              Number of transmitted bytes.

     Statistics: Receive errors:

       statistics : rx_dropped: optional integer
              Number of packets dropped by RX.

       statistics : rx_frame_err: optional integer
              Number of frame alignment errors.

       statistics : rx_over_err: optional integer
              Number of packets with RX overrun.

       statistics : rx_crc_err: optional integer
              Number of CRC errors.

       statistics : rx_errors: optional integer
              Total number of receive errors, greater than or equal to the sum of the above.

     Statistics: Transmit errors:

       statistics : tx_dropped: optional integer
              Number of packets dropped by TX.

       statistics : collisions: optional integer
              Number of collisions.

       statistics : tx_errors: optional integer
              Total number of transmit errors, greater than or equal to the sum of the above.

     Ingress Policing:

       These  settings  control  ingress  policing  for  packets received on this interface. On a
       physical interface, this limits the rate at which traffic is allowed into the system  from
       the  outside; on a virtual interface (one connected to a virtual machine), this limits the
       rate at which the VM is able to transmit.

       Policing is a simple form of quality-of-service that  simply  drops  packets  received  in
       excess  of  the  configured rate. Due to its simplicity, policing is usually less accurate
       and less effective than egress QoS (which is configured using the QoS and Queue tables).

       Policing is currently implemented on Linux and OVS with DPDK. Both implementations  use  a
       simple ``token bucket’’ approach:

              •      The  size of the bucket corresponds to ingress_policing_burst. Initially the
                     bucket is full.

              •      Whenever a packet is received, its size (converted to tokens) is compared to
                     the  number  of  tokens  currently  in the bucket. If the required number of
                     tokens are  available,  they  are  removed  and  the  packet  is  forwarded.
                     Otherwise, the packet is dropped.

              •      Whenever  it  is  not  full,  the bucket is refilled with tokens at the rate
                     specified by ingress_policing_rate.

       Policing interacts badly with some network protocols, and especially  with  fragmented  IP
       packets. Suppose that there is enough network activity to keep the bucket nearly empty all
       the time. Then this token bucket algorithm will forward a single packet  every  so  often,
       with  the period depending on packet size and on the configured rate. All of the fragments
       of an IP packets are normally transmitted back-to-back, as a group. In such  a  situation,
       therefore,  only one of these fragments will be forwarded and the rest will be dropped. IP
       does not provide any way for  the  intended  recipient  to  ask  for  only  the  remaining
       fragments.  In  such  a case there are two likely possibilities for what will happen next:
       either all of the fragments will eventually be retransmitted (as TCP will  do),  in  which
       case  the same problem will recur, or the sender will not realize that its packet has been
       dropped and data will simply be lost (as some UDP-based protocols will do). Either way, it
       is possible that no forward progress will ever occur.

       ingress_policing_rate: integer, at least 0
              Maximum  rate  for  data  received on this interface, in kbps. Data received faster
              than this rate is dropped. Set to 0 (the default) to disable policing.

       ingress_policing_burst: integer, at least 0
              Maximum burst size for data received on this interface, in kb.  The  default  burst
              size if set to 0 is 8000 kbit. This value has no effect if ingress_policing_rate is
              0.

              Specifying a larger burst size lets the  algorithm  be  more  forgiving,  which  is
              important  for protocols like TCP that react severely to dropped packets. The burst
              size should be at least the size of the interface’s MTU. Specifying a value that is
              numerically at least as large as 80% of ingress_policing_rate helps TCP come closer
              to achieving the full rate.

     Bidirectional Forwarding Detection (BFD):

       BFD, defined in RFC 5880 and RFC 5881, allows  point-to-point  detection  of  connectivity
       failures  by  occasional transmission of BFD control messages. Open vSwitch implements BFD
       to serve as a more popular and standards compliant alternative to CFM.

       BFD operates  by  regularly  transmitting  BFD  control  messages  at  a  rate  negotiated
       independently  in  each direction. Each endpoint specifies the rate at which it expects to
       receive control messages, and the rate at  which  it  is  willing  to  transmit  them.  By
       default,  Open  vSwitch  uses  a  detection  multiplier of three, meaning that an endpoint
       signals a connectivity fault if three consecutive BFD control messages fail to arrive.  In
       the  case  of  a  unidirectional  connectivity issue, the system not receiving BFD control
       messages signals the problem to its peer in the messages it transmits.

       The  Open  vSwitch  implementation  of  BFD  aims  to  comply  faithfully  with  RFC  5880
       requirements. Open vSwitch does not implement the optional Authentication or ``Echo Mode’’
       features.

     BFD Configuration:

       A controller sets up key-value pairs in the bfd column to enable and configure BFD.

       bfd : enable: optional string, either true or false
              True to enable BFD on this Interface. If not specified, BFD will not be enabled  by
              default.

       bfd : min_rx: optional string, containing an integer, at least 1
              The shortest interval, in milliseconds, at which this BFD session offers to receive
              BFD control messages. The remote endpoint may choose to send messages at  a  slower
              rate. Defaults to 1000.

       bfd : min_tx: optional string, containing an integer, at least 1
              The  shortest  interval,  in  milliseconds, at which this BFD session is willing to
              transmit BFD control messages. Messages will actually be transmitted  at  a  slower
              rate  if  the  remote  endpoint  is not willing to receive as quickly as specified.
              Defaults to 100.

       bfd : decay_min_rx: optional string, containing an integer
              An alternate receive interval, in milliseconds, that must be greater than or  equal
              to bfd:min_rx. The implementation switches from bfd:min_rx to bfd:decay_min_rx when
              there is no obvious incoming data traffic at the interface, to reduce the  CPU  and
              bandwidth  cost  of  monitoring  an idle interface. This feature may be disabled by
              setting a value of 0. This feature is reset whenever bfd:decay_min_rx or bfd:min_rx
              changes.

       bfd : forwarding_if_rx: optional string, either true or false
              When  true, traffic received on the Interface is used to indicate the capability of
              packet I/O. BFD control packets are still transmitted and received.  At  least  one
              BFD  control  packet  must  be  received  every  100  *  bfd:min_rx amount of time.
              Otherwise, even if traffic are received, the bfd:forwarding will be false.

       bfd : cpath_down: optional string, either true or false
              Set to true to notify the remote endpoint that traffic should not be  forwarded  to
              this system for some reason other than a connectivty failure on the interface being
              monitored. The typical underlying reason is ``concatenated path  down,’’  that  is,
              that connectivity beyond the local system is down. Defaults to false.

       bfd : check_tnl_key: optional string, either true or false
              Set  to true to make BFD accept only control messages with a tunnel key of zero. By
              default, BFD accepts control messages with any tunnel key.

       bfd : bfd_local_src_mac: optional string
              Set to an Ethernet address in the form xx:xx:xx:xx:xx:xx to set  the  MAC  used  as
              source  for  transmitted  BFD  packets.  The  default is the mac address of the BFD
              enabled interface.

       bfd : bfd_local_dst_mac: optional string
              Set to an Ethernet address in the form xx:xx:xx:xx:xx:xx to set  the  MAC  used  as
              destination for transmitted BFD packets. The default is 00:23:20:00:00:01.

       bfd : bfd_remote_dst_mac: optional string
              Set  to  an  Ethernet address in the form xx:xx:xx:xx:xx:xx to set the MAC used for
              checking  the  destination  of  received  BFD  packets.  Packets   with   different
              destination  MAC  will  not  be  considered  as  BFD  packets. If not specified the
              destination MAC address of received BFD packets are not checked.

       bfd : bfd_src_ip: optional string
              Set to an IPv4 address to set the IP address used as  source  for  transmitted  BFD
              packets. The default is 169.254.1.1.

       bfd : bfd_dst_ip: optional string
              Set  to  an  IPv4 address to set the IP address used as destination for transmitted
              BFD packets. The default is 169.254.1.0.

       bfd : oam: optional string
              Some tunnel protocols (such as Geneve) include a bit in the header to indicate that
              the  encapsulated packet is an OAM frame. By setting this to true, BFD packets will
              be marked as OAM if encapsulated in one of these tunnels.

       bfd : mult: optional string, containing an integer, in range 1 to 255
              The  BFD  detection  multiplier,  which  defaults  to  3.  An  endpoint  signals  a
              connectivity  fault if the given number of consecutive BFD control messages fail to
              arrive.

     BFD Status:

       The switch sets key-value pairs in the bfd_status column to report the status  of  BFD  on
       this  interface. When BFD is not enabled, with bfd:enable, the switch clears all key-value
       pairs from bfd_status.

       bfd_status : state: optional string, one of admin_down, down, init, or up
              Reports the state of the  BFD  session.  The  BFD  session  is  fully  healthy  and
              negotiated if UP.

       bfd_status : forwarding: optional string, either true or false
              Reports  whether  the  BFD  session  believes this Interface may be used to forward
              traffic. Typically this means the local session is signaling  UP,  and  the  remote
              system isn’t signaling a problem such as concatenated path down.

       bfd_status : diagnostic: optional string
              A  diagnostic  code  specifying  the  local  system’s reason for the last change in
              session state. The error messages are defined in section 4.1 of [RFC 5880].

       bfd_status : remote_state: optional string, one of admin_down, down, init, or up
              Reports the state of the remote endpoint’s BFD session.

       bfd_status : remote_diagnostic: optional string
              A diagnostic code specifying the remote system’s reason  for  the  last  change  in
              session state. The error messages are defined in section 4.1 of [RFC 5880].

       bfd_status : flap_count: optional string, containing an integer, at least 0
              Counts  the number of bfd_status:forwarding flaps since start. A flap is considered
              as a change of the bfd_status:forwarding value.

     Connectivity Fault Management:

       802.1ag Connectivity Fault Management (CFM) allows a group  of  Maintenance  Points  (MPs)
       called a Maintenance Association (MA) to detect connectivity problems with each other. MPs
       within a MA should have complete and exclusive  interconnectivity.  This  is  verified  by
       occasionally  broadcasting Continuity Check Messages (CCMs) at a configurable transmission
       interval.

       According to the 802.1ag specification, each Maintenance Point should be  configured  out-
       of-band  with  a  list  of  Remote Maintenance Points it should have connectivity to. Open
       vSwitch differs from the specification in this area. It simply assumes the link is faulted
       if no Remote Maintenance Points are reachable, and considers it not faulted otherwise.

       When  operating  over  tunnels  which  have no in_key, or an in_key of flow. CFM will only
       accept CCMs with a tunnel key of zero.

       cfm_mpid: optional integer
              A  Maintenance  Point  ID  (MPID)  uniquely  identifies  each  endpoint  within   a
              Maintenance  Association.  The  MPID  is  used  to  identify this endpoint to other
              Maintenance Points in the MA. Each end of a link  being  monitored  should  have  a
              different MPID. Must be configured to enable CFM on this Interface.

              According  to  the  802.1ag  specification, MPIDs can only range between [1, 8191].
              However, extended mode (see other_config:cfm_extended) supports eight byte MPIDs.

       cfm_flap_count: optional integer
              Counts the number of cfm fault flapps since boot. A flap  is  considered  to  be  a
              change of the cfm_fault value.

       cfm_fault: optional boolean
              Indicates a connectivity fault triggered by an inability to receive heartbeats from
              any remote endpoint. When a fault  is  triggered  on  Interfaces  participating  in
              bonds, they will be disabled.

              Faults  can  be  triggered for several reasons. Most importantly they are triggered
              when no CCMs are received for a period of  3.5  times  the  transmission  interval.
              Faults are also triggered when any CCMs indicate that a Remote Maintenance Point is
              not receiving CCMs but able to send them. Finally, a fault is triggered if a CCM is
              received which indicates unexpected configuration. Notably, this case arises when a
              CCM is received which advertises the local MPID.

       cfm_fault_status : recv: none
              Indicates a CFM fault was  triggered  due  to  a  lack  of  CCMs  received  on  the
              Interface.

       cfm_fault_status : rdi: none
              Indicates  a CFM fault was triggered due to the reception of a CCM with the RDI bit
              flagged. Endpoints set the RDI bit in their CCMs when they are not  receiving  CCMs
              themselves. This typically indicates a unidirectional connectivity failure.

       cfm_fault_status : maid: none
              Indicates a CFM fault was triggered due to the reception of a CCM with a MAID other
              than the one Open vSwitch uses. CFM broadcasts are tagged  with  an  identification
              number  in  addition  to  the  MPID  called  the  MAID.  Open vSwitch only supports
              receiving CCM broadcasts tagged with the MAID it uses internally.

       cfm_fault_status : loopback: none
              Indicates a CFM fault was triggered due to the reception of a CCM  advertising  the
              same  MPID configured in the cfm_mpid column of this Interface. This may indicate a
              loop in the network.

       cfm_fault_status : overflow: none
              Indicates a CFM fault was triggered because the CFM module received CCMs from  more
              remote endpoints than it can keep track of.

       cfm_fault_status : override: none
              Indicates  a  CFM  fault  was  manually  triggered  by  an  administrator  using an
              ovs-appctl command.

       cfm_fault_status : interval: none
              Indicates a CFM fault was triggered due to the reception of a CCM frame  having  an
              invalid interval.

       cfm_remote_opstate: optional string, either down or up
              When  in  extended  mode, indicates the operational state of the remote endpoint as
              either up or down. See other_config:cfm_opstate.

       cfm_health: optional integer, in range 0 to 100
              Indicates the health of the interface as a percentage of CCM frames  received  over
              21  other_config:cfm_intervals.  The  health  of an interface is undefined if it is
              communicating with more than one cfm_remote_mpids. It reduces if healthy heartbeats
              are not received at the expected rate, and gradually improves as healthy heartbeats
              are received at the desired rate. Every 21 other_config:cfm_intervals,  the  health
              of the interface is refreshed.

              As  mentioned  above,  the  faults  can  be triggered for several reasons. The link
              health will deteriorate even if heartbeats are received but they are reported to be
              unhealthy.  An  unhealthy heartbeat in this context is a heartbeat for which either
              some fault is set or is out of sequence. The interface health can be  100  only  on
              receiving healthy heartbeats at the desired rate.

       cfm_remote_mpids: set of integers
              When  CFM  is  properly  configured,  Open  vSwitch  will  occasionally receive CCM
              broadcasts. These broadcasts contain the MPID of the sending Maintenance Point. The
              list  of  MPIDs from which this Interface is receiving broadcasts from is regularly
              collected and written to this column.

       other_config : cfm_interval: optional string, containing an integer
              The interval, in milliseconds,  between  transmissions  of  CFM  heartbeats.  Three
              missed heartbeat receptions indicate a connectivity fault.

              In  standard  operation  only  intervals  of  3, 10, 100, 1,000, 10,000, 60,000, or
              600,000 ms are supported. Other values will be rounded down to the nearest value on
              the list. Extended mode (see other_config:cfm_extended) supports any interval up to
              65,535 ms. In either mode, the default is 1000 ms.

              We do not recommend using intervals less than 100 ms.

       other_config : cfm_extended: optional string, either true or false
              When true, the CFM module operates in extended  mode.  This  causes  it  to  use  a
              nonstandard destination address to avoid conflicting with compliant implementations
              which may be running  concurrently  on  the  network.  Furthermore,  extended  mode
              increases the accuracy of the cfm_interval configuration parameter by breaking wire
              compatibility with 802.1ag compliant  implementations.  And  extended  mode  allows
              eight byte MPIDs. Defaults to false.

       other_config : cfm_demand: optional string, either true or false
              When true, and other_config:cfm_extended is true, the CFM module operates in demand
              mode. When in demand mode, traffic received on the Interface is  used  to  indicate
              liveness.  CCMs  are  still  transmitted  and  received.  At  least one CCM must be
              received every 100 * other_config:cfm_interval amount of time. Otherwise,  even  if
              traffic are received, the CFM module will raise the connectivity fault.

              Demand mode has a couple of caveats:

              •      To  ensure  that  ovs-vswitchd  has  enough time to pull statistics from the
                     datapath,   the   fault   detection   interval   is    set    to    3.5    *
                     MAX(other_config:cfm_interval, 500) ms.

              •      To  avoid  ambiguity,  demand  mode  disables itself when there are multiple
                     remote maintenance points.

              •      If   the   Interface   is   heavily   congested,   CCMs    containing    the
                     other_config:cfm_opstate  status  may  be  dropped  causing  changes  in the
                     operational state to be delayed. Similarly, if CCMs containing the  RDI  bit
                     are not received, unidirectional link failures may not be detected.

       other_config : cfm_opstate: optional string, either down or up
              When down, the CFM module marks all CCMs it generates as operationally down without
              triggering a fault. This allows remote maintenance points to choose not to  forward
              traffic  to  the  Interface on which this CFM module is running. Currently, in Open
              vSwitch, the opdown bit of CCMs affects Interfaces participating in bonds, and  the
              bundle  OpenFlow  action. This setting is ignored when CFM is not in extended mode.
              Defaults to up.

       other_config : cfm_ccm_vlan: optional string, containing an integer, in range 1 to 4,095
              When set, the CFM module will apply a VLAN tag to all CCMs it  generates  with  the
              given  value. May be the string random in which case each CCM will be tagged with a
              different randomly generated VLAN.

       other_config : cfm_ccm_pcp: optional string, containing an integer, in range 1 to 7
              When set, the CFM module will apply a VLAN tag to all CCMs it  generates  with  the
              given   PCP   value,  the  VLAN  ID  of  the  tag  is  governed  by  the  value  of
              other_config:cfm_ccm_vlan. If other_config:cfm_ccm_vlan is unset, a VLAN ID of zero
              is used.

     Bonding Configuration:

       other_config : lacp-port-id: optional string, containing an integer, in range 1 to 65,535
              The  LACP  port  ID  of  this  Interface. Port IDs are used in LACP negotiations to
              identify individual ports participating in a bond.

       other_config : lacp-port-priority: optional string, containing an integer, in range  1  to
       65,535
              The  LACP  port  priority  of  this Interface. In LACP negotiations Interfaces with
              numerically lower priorities are preferred for aggregation.

       other_config : lacp-aggregation-key: optional string, containing an integer, in range 1 to
       65,535
              The  LACP  aggregation key of this Interface. Interfaces with different aggregation
              keys may not be active within a given Port at the same time.

     Virtual Machine Identifiers:

       These key-value pairs specifically  apply  to  an  interface  that  represents  a  virtual
       Ethernet  interface  connected  to  a virtual machine. These key-value pairs should not be
       present for other types of interfaces. Keys whose names end  in  -uuid  have  values  that
       uniquely  identify the entity in question. For a Citrix XenServer hypervisor, these values
       are UUIDs in RFC 4122 format. Other hypervisors may use other formats.

       external_ids : attached-mac: optional string
              The MAC address programmed into the ``virtual hardware’’ for this interface, in the
              form xx:xx:xx:xx:xx:xx. For Citrix XenServer, this is the value of the MAC field in
              the VIF record for this interface.

       external_ids : iface-id: optional string
              A system-unique identifier for the interface. On XenServer, this will  commonly  be
              the same as external_ids:xs-vif-uuid.

       external_ids : iface-status: optional string, either active or inactive
              Hypervisors  may  sometimes  have  more  than one interface associated with a given
              external_ids:iface-id, only one of which is actually in use at a  given  time.  For
              example, in some circumstances XenServer has both a ``tap’’ and a ``vif’’ interface
              for a single external_ids:iface-id, but  only  uses  one  of  them  at  a  time.  A
              hypervisor  that  behaves  this way must mark the currently in use interface active
              and the others inactive. A hypervisor that never has more than one interface for  a
              given    external_ids:iface-id   may   mark   that   interface   active   or   omit
              external_ids:iface-status entirely.

              During VM migration, a given  external_ids:iface-id  might  transiently  be  marked
              active   on   two   different   hypervisors.   That  is,  active  means  that  this
              external_ids:iface-id is the active instance within a single hypervisor, not  in  a
              broader  scope. There is one exception: some hypervisors support ``migration’’ from
              a given hypervisor to  itself  (most  often  for  test  purposes).  During  such  a
              ``migration,’’  two  instances  of  a  single  external_ids:iface-id  might both be
              briefly marked active on a single hypervisor.

       external_ids : xs-vif-uuid: optional string
              The virtual interface associated with this interface.

       external_ids : xs-network-uuid: optional string
              The virtual network to which this interface is attached.

       external_ids : vm-id: optional string
              The VM to which this interface belongs. On XenServer, this  will  be  the  same  as
              external_ids:xs-vm-uuid.

       external_ids : xs-vm-uuid: optional string
              The VM to which this interface belongs.

     Auto Attach Configuration:

       Auto Attach configuration for a particular interface.

       lldp : enable: optional string, either true or false
              True  to  enable LLDP on this Interface. If not specified, LLDP will be disabled by
              default.

     Flow control Configuration:

       Ethernet flow control defined in IEEE 802.1Qbb provides link level flow control using  MAC
       pause frames. Implemented only for interfaces with type dpdk.

       options : rx-flow-ctrl: optional string, either true or false
              Set  to  true  to  enable  Rx  flow  control on physical ports. By default, Rx flow
              control is disabled.

       options : tx-flow-ctrl: optional string, either true or false
              Set to true to enable Tx flow control  on  physical  ports.  By  default,  Tx  flow
              control is disabled.

       options : flow-ctrl-autoneg: optional string, either true or false
              Set  to true to enable flow control auto negotiation on physical ports. By default,
              auto-neg is disabled.

     Link State Change detection mode:

       options : dpdk-lsc-interrupt: optional string, either true or false
              Set this value to true to configure interrupt mode  for  Link  State  Change  (LSC)
              detection instead of poll mode for the DPDK interface.

              If this value is not set, poll mode is configured.

              This parameter has an effect only on netdev dpdk interfaces.

     Common Columns:

       The overall purpose of these columns is described under Common Columns at the beginning of
       this document.

       other_config: map of string-string pairs

       external_ids: map of string-string pairs

Flow_Table TABLE

       Configuration for a particular OpenFlow table.

   Summary:
       name                          optional string
       Eviction Policy:
         flow_limit                  optional integer, at least 0
         overflow_policy             optional string, either evict or refuse
         groups                      set of strings
       Classifier Optimization:
         prefixes                    set of up to 3 strings
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       name: optional string
              The table’s name. Set this column to change the name that controllers will  receive
              when  they  request table statistics, e.g. ovs-ofctl dump-tables. The name does not
              affect switch behavior.

     Eviction Policy:

       Open vSwitch supports limiting the number of flows that may be installed in a flow  table,
       via  the  flow_limit  column.  When adding a flow would exceed this limit, by default Open
       vSwitch reports an error, but there are two ways to  configure  Open  vSwitch  to  instead
       delete (``evict’’) a flow to make room for the new one:

              •      Set the overflow_policy column to evict.

              •      Send  an OpenFlow 1.4+ ``table mod request’’ to enable eviction for the flow
                     table (e.g. ovs-ofctl -O OpenFlow14 mod-table br0 0 evict to enable eviction
                     on flow table 0 of bridge br0).

       When  a  flow  must  be  evicted  due  to overflow, the flow to evict is chosen through an
       approximation of the following  algorithm.  This  algorithm  is  used  regardless  of  how
       eviction was enabled:

              1.  Divide  the flows in the table into groups based on the values of the fields or
                  subfields specified in the groups column, so that all of the flows in  a  given
                  group have the same values for those fields. If a flow does not specify a given
                  field, that field’s value is treated as 0. If groups is empty, then all of  the
                  flows in the flow table are treated as a single group.

              2.  Consider  the  flows in the largest group, that is, the group that contains the
                  greatest number of flows. If two or more  groups  all  have  the  same  largest
                  number of flows, consider the flows in all of those groups.

              3.  If  the  flows  under consideration have different importance values, eliminate
                  from  consideration  any  flows  except  those  with  the  lowest   importance.
                  (``Importance,’’  a  16-bit integer value attached to each flow, was introduced
                  in OpenFlow 1.4. Flows inserted with older versions of OpenFlow always have  an
                  importance of 0.)

              4.  Among  the  flows under consideration, choose the flow that expires soonest for
                  eviction.

       The eviction process only considers flows that have an idle timeout  or  a  hard  timeout.
       That  is,  eviction  never  deletes  permanent  flows.  (Permanent  flows do count against
       flow_limit.)

       flow_limit: optional integer, at least 0
              If set, limits the number of flows that may be added to the table. Open vSwitch may
              limit  the  number  of  flows  in  a  table for other reasons, e.g. due to hardware
              limitations or for resource availability or performance reasons.

       overflow_policy: optional string, either evict or refuse
              Controls the switch’s behavior when an OpenFlow  flow  table  modification  request
              would add flows in excess of flow_limit. The supported values are:

              refuse Refuse  to  add  the  flow  or  flows.  This is also the default policy when
                     overflow_policy is unset.

              evict  Delete a flow chosen according to the algorithm described above.

       groups: set of strings
              When overflow_policy is evict, this controls how flows are chosen for eviction when
              the  flow  table would otherwise exceed flow_limit flows. Its value is a set of NXM
              fields  or  sub-fields,  each  of  which  takes  one  of  the  forms   field[]   or
              field[start..end],  e.g.  NXM_OF_IN_PORT[].  Please  see meta-flow.h for a complete
              list of NXM field names.

              Open vSwitch ignores any invalid or unknown field specifications.

              When eviction is not enabled, via  overflow_policy  or  an  OpenFlow  1.4+  ``table
              mod,’’ this column has no effect.

     Classifier Optimization:

       prefixes: set of up to 3 strings
              This  string set specifies which fields should be used for address prefix tracking.
              Prefix tracking allows the classifier to skip  rules  with  longer  than  necessary
              prefixes, resulting in better wildcarding for datapath flows.

              Prefix  tracking may be beneficial when a flow table contains matches on IP address
              fields with different prefix lengths. For example, when a flow  table  contains  IP
              address  matches  on  both  full  addresses  and  proper prefixes, the full address
              matches will typically cause the datapath flow to  un-wildcard  the  whole  address
              field  (depending  on  flow  entry  priorities).  In  this  case each packet with a
              different address gets handed to the userspace for flow  processing  and  generates
              its  own  datapath  flow.  With  prefix  tracking  enabled for the address field in
              question packets with addresses matching shorter prefixes would  generate  datapath
              flows  where the irrelevant address bits are wildcarded, allowing the same datapath
              flow to handle all the packets within the prefix in question.  In  this  case  many
              userspace upcalls can be avoided and the overall performance can be better.

              This is a performance optimization only, so packets will receive the same treatment
              with or without prefix tracking.

              The supported fields are: tun_id,  tun_src,  tun_dst,  tun_ipv6_src,  tun_ipv6_dst,
              nw_src,  nw_dst (or aliases ip_src and ip_dst), ipv6_src, and ipv6_dst. (Using this
              feature for tun_id would only make sense if the tunnel IDs  have  prefix  structure
              similar to IP addresses.)

              By  default, the prefixes=ip_dst,ip_src are used on each flow table. This instructs
              the flow classifier to track the IP destination and source addresses  used  by  the
              rules in this specific flow table.

              The  keyword  none  is  recognized  as  an explicit override of the default values,
              causing no prefix fields to be tracked.

              To set the prefix fields, the flow table record needs to exist:

              ovs-vsctl  set  Bridge  br0  flow_tables:0=@N1  --   --id=@N1   create   Flow_Table
              name=table0
                     Creates a flow table record for the OpenFlow table number 0.

              ovs-vsctl set Flow_Table table0 prefixes=ip_dst,ip_src
                     Enables prefix tracking for IP source and destination address fields.

              There  is  a  maximum  number of fields that can be enabled for any one flow table.
              Currently this limit is 3.

     Common Columns:

       The overall purpose of these columns is described under Common Columns at the beginning of
       this document.

       external_ids: map of string-string pairs

QoS TABLE

       Quality of Service (QoS) configuration for each Port that references it.

   Summary:
       type                          string
       queues                        map of integer-Queue pairs, key in range 0 to 4,294,967,295
       Configuration for linux-htb and linux-hfsc:
         other_config : max-rate     optional string, containing an integer
       Configuration for egress-policer QoS:
         other_config : cir          optional string, containing an integer
         other_config : cbs          optional string, containing an integer
         other_config : eir          optional string, containing an integer
         other_config : ebs          optional string, containing an integer
       Configuration for linux-sfq:
         other_config : perturb      optional string, containing an integer
         other_config : quantum      optional string, containing an integer
       Configuration for linux-netem:
         other_config : latency      optional string, containing an integer
         other_config : limit        optional string, containing an integer
         other_config : loss         optional string, containing an integer
       Common Columns:
         other_config                map of string-string pairs
         external_ids                map of string-string pairs

   Details:
       type: string
              The type of QoS to implement. The currently defined types are listed below:

              linux-htb
                     Linux   ``hierarchy  token  bucket’’  classifier.  See  tc-htb(8)  (also  at
                     http://linux.die.net/man/8/tc-htb)      and       the       HTB       manual
                     (http://luxik.cdi.cz/~devik/qos/htb/manual/userg.htm) for information on how
                     this classifier works and how to configure it.

              linux-hfsc
                     Linux    "Hierarchical    Fair    Service     Curve"     classifier.     See
                     http://linux-ip.net/articles/hfsc.en/ for information on how this classifier
                     works.

              linux-sfq
                     Linux ``Stochastic Fairness Queueing’’ classifier. See  tc-sfq(8)  (also  at
                     http://linux.die.net/man/8/tc-sfq)  for  information  on how this classifier
                     works.

              linux-codel
                     Linux  ``Controlled   Delay’’   classifier.   See   tc-codel(8)   (also   at
                     http://man7.org/linux/man-pages/man8/tc-codel.8.html) for information on how
                     this classifier works.

              linux-fq_codel
                     Linux ``Fair Queuing with Controlled Delay’’ classifier. See  tc-fq_codel(8)
                     (also    at   http://man7.org/linux/man-pages/man8/tc-fq_codel.8.html)   for
                     information on how this classifier works.

              linux-netem
                     Linux  ``Network   Emulator’’   classifier.   See   tc-netem(8)   (also   at
                     http://man7.org/linux/man-pages/man8/tc-netem.8.html) for information on how
                     this classifier works.

              linux-noop
                     Linux ``No operation.’’ By default, Open vSwitch manages quality of  service
                     on  all  of  its  configured  ports.  This  can  be  helpful,  but sometimes
                     administrators prefer to  use  other  software  to  manage  QoS.  This  type
                     prevents Open vSwitch from changing the QoS configuration for a port.

              egress-policer
                     A  DPDK  egress  policer  algorithm  using  the  DPDK rte_meter library. The
                     rte_meter library provides an implementation which allows the  metering  and
                     policing  of traffic. The implementation in OVS essentially creates a single
                     token bucket used to police traffic.  It  should  be  noted  that  when  the
                     rte_meter  is configured as part of QoS there will be a performance overhead
                     as the rte_meter itself will consume CPU cycles in order to police  traffic.
                     These  CPU  cycles  ordinarily  are used for packet proccessing. As such the
                     drop in performance will be noticed in terms of  overall  aggregate  traffic
                     throughput.

              trtcm-policer
                     A  DPDK  egress  policer  algorithm  using  RFC 4115’s Two-Rate, Three-Color
                     marker. It’s a two-level hierarchical policer which first does a color-blind
                     marking of the traffic at the queue level, followed by a color-aware marking
                     at the port level.  At  the  end  traffic  marked  as  Green  or  Yellow  is
                     forwarded,  Red  is  dropped.  For details on how traffic is marked, see RFC
                     4115. If the ``default queue’’, 0,  is  not  configured  it’s  automatically
                     created with the same other_config values as the physical port.

       queues: map of integer-Queue pairs, key in range 0 to 4,294,967,295
              A  map  from  queue  numbers to Queue records. The supported range of queue numbers
              depend on type. The queue numbers are the same as the queue_id used in OpenFlow  in
              struct ofp_action_enqueue and other structures.

              Queue  0  is  the  ``default queue.’’ It is used by OpenFlow output actions when no
              specific queue has been set. When no configuration for queue 0 is  present,  it  is
              automatically  configured  as  if  a  Queue record with empty dscp and other_config
              columns had been specified. (Before version 1.6, Open vSwitch would leave  queue  0
              unconfigured  in this case. With some queuing disciplines, this dropped all packets
              destined for the default queue.)

     Configuration for linux-htb and linux-hfsc:

       The linux-htb and linux-hfsc classes support the following key-value pair:

       other_config : max-rate: optional string, containing an integer
              Maximum rate shared by all queued traffic, in bit/s. Optional.  If  not  specified,
              for  physical  interfaces, the default is the link rate. For other interfaces or if
              the link rate cannot be determined, the default is currently 100 Mbps.

     Configuration for egress-policer QoS:

       QoS type egress-policer provides egress policing for userspace port types  with  DPDK.  It
       has the following key-value pairs defined.

       other_config : cir: optional string, containing an integer
              The Committed Information Rate (CIR) is measured in bytes of IP packets per second,
              i.e. it includes the IP header, but not link specific (e.g. Ethernet) headers. This
              represents the bytes per second rate at which the token bucket will be updated. The
              cir value is calculated by (pps x packet data size). For example  assuming  a  user
              wishes  to  limit  a  stream consisting of 64 byte packets to 1 million packets per
              second the CIR would be set to to to  46000000.  This  value  can  be  broken  into
              ’1,000,000  x  46’.  Where 1,000,000 is the policing rate for the number of packets
              per second and 46 represents the size of the packet data for a 64 bytes  IP  packet
              without 14 bytes Ethernet and 4 bytes FCS header.

       other_config : cbs: optional string, containing an integer
              The  Committed Burst Size (CBS) is measured in bytes and represents a token bucket.
              At a minimum this value should be be set to the expected largest size packet in the
              traffic  stream.  In practice larger values may be used to increase the size of the
              token bucket. If a packet can be transmitted then the cbs will  be  decremented  by
              the number of bytes/tokens of the packet. If there are not enough tokens in the cbs
              bucket the packet will be dropped.

       other_config : eir: optional string, containing an integer
              The Excess Information Rate (EIR) is measured in bytes of IP  packets  per  second,
              i.e. it includes the IP header, but not link specific (e.g. Ethernet) headers. This
              represents the bytes per second rate at which the token bucket will be updated. The
              eir  value  is  calculated by (pps x packet data size). For example assuming a user
              wishes to limit a stream consisting of 64 byte packets to  1  million  packets  per
              second  the  EIR  would  be  set  to  to to 46000000. This value can be broken into
              ’1,000,000 x 46’. Where 1,000,000 is the policing rate for the  number  of  packets
              per  second  and 46 represents the size of the packet data for a 64 bytes IP packet
              without 14 bytes Ethernet and 4 bytes FCS header.

       other_config : ebs: optional string, containing an integer
              The Excess Burst Size (EBS) is measured in bytes and represents a token bucket.  At
              a  minimum  this  value should be be set to the expected largest size packet in the
              traffic stream. In practice larger values may be used to increase the size  of  the
              token  bucket.  If  a packet can be transmitted then the ebs will be decremented by
              the number of bytes/tokens of the packet. If there are not enough tokens in the cbs
              bucket the packet might be dropped.

     Configuration for linux-sfq:

       The linux-sfq QoS supports the following key-value pairs:

       other_config : perturb: optional string, containing an integer
              Number of seconds between consecutive perturbations in hashing algorithm. Different
              flows can end up in the same hash bucket causing unfairness. Perturbation’s goal is
              to  remove  possible unfairness. The default and recommended value is 10. Too low a
              value is discouraged because each perturbation can cause packet reordering.

       other_config : quantum: optional string, containing an integer
              Number of bytes linux-sfq QoS can dequeue in one turn in round-robin from one flow.
              The default and recommended value is equal to interface’s MTU.

     Configuration for linux-netem:

       The linux-netem QoS supports the following key-value pairs:

       other_config : latency: optional string, containing an integer
              Adds  the  chosen  delay  to  the packets outgoing to chosen network interface. The
              latency value expressed in us.

       other_config : limit: optional string, containing an integer
              Maximum number of packets the qdisc may hold queued at a time. The default value is
              1000.

       other_config : loss: optional string, containing an integer
              Adds  an  independent  loss  probability  to  the  packets outgoing from the chosen
              network interface.

     Common Columns:

       The overall purpose of these columns is described under Common Columns at the beginning of
       this document.

       other_config: map of string-string pairs

       external_ids: map of string-string pairs

Queue TABLE

       A  configuration  for  a  port  output queue, used in configuring Quality of Service (QoS)
       features. May be referenced by queues column in QoS table.

   Summary:
       dscp                          optional integer, in range 0 to 63
       Configuration for linux-htb QoS:
         other_config : min-rate     optional string, containing an integer, at least 1
         other_config : max-rate     optional string, containing an integer, at least 1
         other_config : burst        optional string, containing an integer, at least 1
         other_config : priority     optional string,  containing  an  integer,  in  range  0  to
                                     4,294,967,295
       Configuration for linux-hfsc QoS:
         other_config : min-rate     optional string, containing an integer, at least 1
         other_config : max-rate     optional string, containing an integer, at least 1
       Common Columns:
         other_config                map of string-string pairs
         external_ids                map of string-string pairs

   Details:
       dscp: optional integer, in range 0 to 63
              If set, Open vSwitch will mark all traffic egressing this Queue with the given DSCP
              bits. Traffic egressing the default Queue is  only  marked  if  it  was  explicitly
              selected as the Queue at the time the packet was output. If unset, the DSCP bits of
              traffic egressing this Queue will remain unchanged.

     Configuration for linux-htb QoS:

       QoS type linux-htb may use queue_ids less than 61440. It has the following key-value pairs
       defined.

       other_config : min-rate: optional string, containing an integer, at least 1
              Minimum guaranteed bandwidth, in bit/s.

       other_config : max-rate: optional string, containing an integer, at least 1
              Maximum  allowed bandwidth, in bit/s. Optional. If specified, the queue’s rate will
              not be allowed  to  exceed  the  specified  value,  even  if  excess  bandwidth  is
              available. If unspecified, defaults to no limit.

       other_config : burst: optional string, containing an integer, at least 1
              Burst  size,  in  bits.  This is the maximum amount of ``credits’’ that a queue can
              accumulate while it is idle. Optional.  Details  of  the  linux-htb  implementation
              require a minimum burst size, so a too-small burst will be silently ignored.

       other_config   :  priority:  optional  string,  containing  an  integer,  in  range  0  to
       4,294,967,295
              A queue with a smaller priority will receive all the excess bandwidth that  it  can
              use  before  a queue with a larger value receives any. Specific priority values are
              unimportant; only relative ordering matters. Defaults to 0 if unspecified.

     Configuration for linux-hfsc QoS:

       QoS type linux-hfsc may use queue_ids less than 61440.  It  has  the  following  key-value
       pairs defined.

       other_config : min-rate: optional string, containing an integer, at least 1
              Minimum guaranteed bandwidth, in bit/s.

       other_config : max-rate: optional string, containing an integer, at least 1
              Maximum  allowed bandwidth, in bit/s. Optional. If specified, the queue’s rate will
              not be allowed  to  exceed  the  specified  value,  even  if  excess  bandwidth  is
              available. If unspecified, defaults to no limit.

     Common Columns:

       The overall purpose of these columns is described under Common Columns at the beginning of
       this document.

       other_config: map of string-string pairs

       external_ids: map of string-string pairs

Mirror TABLE

       A port mirror within a Bridge.

       A port mirror configures a bridge to send selected frames to special  ``mirrored’’  ports,
       in  addition  to  their  normal destinations. Mirroring traffic may also be referred to as
       SPAN or RSPAN, depending on how the mirrored traffic is sent.

       When a packet enters an Open vSwitch bridge, it becomes eligible for  mirroring  based  on
       its  ingress port and VLAN. As the packet travels through the flow tables, each time it is
       output to a port, it becomes eligible for mirroring based on the egress port and VLAN.  In
       Open  vSwitch  2.5 and later, mirroring occurs just after a packet first becomes eligible,
       using the packet as it exists at that point; in Open vSwitch 2.4  and  earlier,  mirroring
       occurs only after a packet has traversed all the flow tables, using the original packet as
       it entered the bridge. This makes a difference only  when  the  flow  table  modifies  the
       packet:  in  Open  vSwitch 2.4, the modifications are never visible to mirrors, whereas in
       Open vSwitch 2.5 and later modifications made  before  the  first  output  that  makes  it
       eligible for mirroring to a particular destination are visible.

       A  packet  that enters an Open vSwitch bridge is mirrored to a particular destination only
       once, even if it is eligible for multiple reasons. For example, a packet would be mirrored
       to  a  particular output_port only once, even if it is selected for mirroring to that port
       by select_dst_port and select_src_port in the same or different Mirror records.

   Summary:
       name                          string
       Selecting Packets for Mirroring:
         select_all                  boolean
         select_dst_port             set of weak reference to Ports
         select_src_port             set of weak reference to Ports
         select_vlan                 set of up to 4,096 integers, in range 0 to 4,095
       Mirroring Destination Configuration:
         output_port                 optional weak reference to Port
         output_vlan                 optional integer, in range 1 to 4,095
         snaplen                     optional integer, in range 14 to 65,535
       Statistics: Mirror counters:
         statistics : tx_packets     optional integer
         statistics : tx_bytes       optional integer
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       name: string
              Arbitrary identifier for the Mirror.

     Selecting Packets for Mirroring:

       To be selected for mirroring, a given packet must enter or  leave  the  bridge  through  a
       selected port and it must also be in one of the selected VLANs.

       select_all: boolean
              If true, every packet arriving or departing on any port is selected for mirroring.

       select_dst_port: set of weak reference to Ports
              Ports on which departing packets are selected for mirroring.

       select_src_port: set of weak reference to Ports
              Ports on which arriving packets are selected for mirroring.

       select_vlan: set of up to 4,096 integers, in range 0 to 4,095
              VLANs  on which packets are selected for mirroring. An empty set selects packets on
              all VLANs.

     Mirroring Destination Configuration:

       These columns are mutually exclusive. Exactly one of them must be nonempty.

       output_port: optional weak reference to Port
              Output port for selected packets, if nonempty.

              Specifying a port for mirror output reserves that port exclusively  for  mirroring.
              No frames other than those selected for mirroring via this column will be forwarded
              to the port, and any frames received on the port will be discarded.

              The output port may be any kind of port supported by Open vSwitch. It may  be,  for
              example, a physical port (sometimes called SPAN) or a GRE tunnel.

       output_vlan: optional integer, in range 1 to 4,095
              Output VLAN for selected packets, if nonempty.

              The  frames will be sent out all ports that trunk output_vlan, as well as any ports
              with implicit VLAN output_vlan. When a mirrored frame is sent out a trunk port, the
              frame’s VLAN tag will be set to output_vlan, replacing any existing tag; when it is
              sent out an implicit VLAN port,  the  frame  will  not  be  tagged.  This  type  of
              mirroring is sometimes called RSPAN.

              See  the  documentation  for other_config:forward-bpdu in the Interface table for a
              list of destination MAC addresses which will not be mirrored to  a  VLAN  to  avoid
              confusing switches that interpret the protocols that they represent.

              Please  note:  Mirroring  to  a  VLAN can disrupt a network that contains unmanaged
              switches. Consider an unmanaged physical switch with two ports: port  1,  connected
              to  an  end  host,  and  port  2, connected to an Open vSwitch configured to mirror
              received packets into VLAN 123 on port 2. Suppose that the end host sends a  packet
              on  port  1  that the physical switch forwards to port 2. The Open vSwitch forwards
              this packet to its destination and then reflects it back on port  2  in  VLAN  123.
              This  reflected  packet  causes  the  unmanaged  physical switch to replace the MAC
              learning table entry, which correctly pointed to port 1, with one that  incorrectly
              points  to  port 2. Afterward, the physical switch will direct packets destined for
              the end host to the Open vSwitch on port 2, instead of to the end host on  port  1,
              disrupting  connectivity.  If mirroring to a VLAN is desired in this scenario, then
              the physical switch must be replaced by one that learns  Ethernet  addresses  on  a
              per-VLAN  basis.  In  addition,  learning should be disabled on the VLAN containing
              mirrored traffic. If this is not done then intermediate switches will learn the MAC
              address  of  each end host from the mirrored traffic. If packets being sent to that
              end host are also mirrored, then they will be dropped since the switch will attempt
              to  send  them  out  the input port. Disabling learning for the VLAN will cause the
              switch to correctly send the packet out all ports configured for that VLAN. If Open
              vSwitch is being used as an intermediate switch, learning can be disabled by adding
              the mirrored VLAN to flood_vlans in the appropriate Bridge table or tables.

              Mirroring to a GRE tunnel has fewer caveats than mirroring to  a  VLAN  and  should
              generally be preferred.

       snaplen: optional integer, in range 14 to 65,535
              Maximum per-packet number of bytes to mirror.

              A  mirrored  packet  with size larger than snaplen will be truncated in datapath to
              snaplen bytes before sending to the mirror output port. If omitted, packets are not
              truncated.

     Statistics: Mirror counters:

       Key-value  pairs  that  report  mirror  statistics.  The  update  period  is controlled by
       other_config:stats-update-interval in the Open_vSwitch table.

       statistics : tx_packets: optional integer
              Number of packets transmitted through this mirror.

       statistics : tx_bytes: optional integer
              Number of bytes transmitted through this mirror.

     Common Columns:

       The overall purpose of these columns is described under Common Columns at the beginning of
       this document.

       external_ids: map of string-string pairs

Controller TABLE

       An OpenFlow controller.

   Summary:
       Core Features:
         type                        optional string, either primary or service
         target                      string
         connection_mode             optional string, either in-band or out-of-band
       Controller Failure Detection and Handling:
         max_backoff                 optional integer, at least 1,000
         inactivity_probe            optional integer
       Asynchronous Messages:
         enable_async_messages       optional boolean
         Controller Rate Limiting:
            controller_queue_size    optional integer, in range 1 to 512
            controller_rate_limit    optional integer, at least 100
            controller_burst_limit   optional integer, at least 25
            Controller Rate Limiting Statistics:
              status : packet-in-TYPE-bypassed
                                     optional string, containing an integer, at least 0
              status : packet-in-TYPE-queued
                                     optional string, containing an integer, at least 0
              status : packet-in-TYPE-dropped
                                     optional string, containing an integer, at least 0
              status : packet-in-TYPE-backlog
                                     optional string, containing an integer, at least 0
       Additional In-Band Configuration:
         local_ip                    optional string
         local_netmask               optional string
         local_gateway               optional string
       Controller Status:
         is_connected                boolean
         role                        optional string, one of master, other, or slave
         status : last_error         optional string
         status : state              optional  string,  one of ACTIVE, BACKOFF, CONNECTING, IDLE,
                                     or VOID
         status : sec_since_connect  optional string, containing an integer, at least 0
         status : sec_since_disconnect
                                     optional string, containing an integer, at least 1
       Connection Parameters:
         other_config : dscp         optional string, containing an integer
       Common Columns:
         external_ids                map of string-string pairs
         other_config                map of string-string pairs

   Details:
     Core Features:

       type: optional string, either primary or service
              Open vSwitch supports two kinds of OpenFlow controllers.  A  bridge  may  have  any
              number of each kind:

              Primary controllers
                     This  is  the  kind of controller envisioned by the OpenFlow specifications.
                     Usually, a primary controller implements a network policy by  taking  charge
                     of the switch’s flow table.

                     The fail_mode column in the Bridge table applies to primary controllers.

                     When  multiple  primary controllers are configured, Open vSwitch connects to
                     all of them  simultaneously.  OpenFlow  provides  few  facilities  to  allow
                     multiple  controllers  to coordinate in interacting with a single switch, so
                     more than one primary controller should be specified only if the controllers
                     are themselves designed to coordinate with each other.

              Service controllers
                     These  kinds  of OpenFlow controller connections are intended for occasional
                     support  and  maintenance  use,  e.g.  with  ovs-ofctl.  Usually  a  service
                     controller  connects  only  briefly  to inspect or modify some of a switch’s
                     state.

                     The fail_mode  column  in  the  Bridge  table  does  not  apply  to  service
                     controllers.

              By  default,  Open  vSwitch  treats  controllers  with active connection methods as
              primary  controllers  and  those  with  passive  connection  methods   as   service
              controllers. Set this column to the desired type to override this default.

       target: string
              Connection method for controller.

              The following active connection methods are currently supported:

              ssl:host[:port]
                     The  specified SSL port on the host at the given host, which can either be a
                     DNS name (if built with unbound library) or an IP address. The ssl column in
                     the  Open_vSwitch  table  must  point to a valid SSL configuration when this
                     form is used.

                     If port is not specified, it defaults to 6653.

                     SSL support is an optional feature that is not always built as part of  Open
                     vSwitch.

              tcp:host[:port]
                     The  specified TCP port on the host at the given host, which can either be a
                     DNS name (if built with unbound library) or an IP address (IPv4 or IPv6). If
                     host is an IPv6 address, wrap it in square brackets, e.g. tcp:[::1]:6653.

                     If port is not specified, it defaults to 6653.

              The following passive connection methods are currently supported:

              pssl:[port][:host]
                     Listens  for  SSL  connections on the specified TCP port. If host, which can
                     either be a DNS name (if built with unbound library) or an  IP  address,  is
                     specified,  then  connections  are  restricted  to the resolved or specified
                     local IP address (either IPv4 or IPv6). If host is an IPv6 address, wrap  it
                     in square brackets, e.g. pssl:6653:[::1].

                     If port is not specified, it defaults to 6653. If host is not specified then
                     it listens only on IPv4 (but not IPv6) addresses.  The  ssl  column  in  the
                     Open_vSwitch table must point to a valid SSL configuration when this form is
                     used.

                     If port is not specified, it currently to 6653.

                     SSL support is an optional feature that is not always built as part of  Open
                     vSwitch.

              ptcp:[port][:host]
                     Listens for connections on the specified TCP port. If host, which can either
                     be a DNS name  (if  built  with  unbound  library)  or  an  IP  address,  is
                     specified,  then  connections  are  restricted  to the resolved or specified
                     local IP address (either IPv4 or IPv6). If host is an IPv6 address, wrap  it
                     in  square  brackets, e.g. ptcp:6653:[::1]. If host is not specified then it
                     listens only on IPv4 addresses.

                     If port is not specified, it defaults to 6653.

              When multiple controllers are configured for a single  bridge,  the  target  values
              must be unique. Duplicate target values yield unspecified results.

       connection_mode: optional string, either in-band or out-of-band
              If  it  is  specified,  this  setting  must  be  one  of the following strings that
              describes how Open vSwitch contacts this OpenFlow controller over the network:

              in-band
                     In this mode, this controller’s OpenFlow traffic  travels  over  the  bridge
                     associated  with  the  controller.  With  this  setting, Open vSwitch allows
                     traffic to and from  the  controller  regardless  of  the  contents  of  the
                     OpenFlow flow table. (Otherwise, Open vSwitch would never be able to connect
                     to the controller, because it did not have a flow to enable it.) This is the
                     most  common  connection  mode  because  it is not necessary to maintain two
                     independent networks.

              out-of-band
                     In this mode, OpenFlow traffic uses a  control  network  separate  from  the
                     bridge associated with this controller, that is, the bridge does not use any
                     of its own network devices to communicate with the controller.  The  control
                     network  must  be  configured  separately,  before  or after ovs-vswitchd is
                     started.

              If not specified, the default is implementation-specific.

     Controller Failure Detection and Handling:

       max_backoff: optional integer, at least 1,000
              Maximum number of milliseconds to wait  between  connection  attempts.  Default  is
              implementation-specific.

       inactivity_probe: optional integer
              Maximum  number  of  milliseconds  of  idle time on connection to controller before
              sending an inactivity probe message. If Open vSwitch does not communicate with  the
              controller for the specified number of seconds, it will send a probe. If a response
              is not received for the same additional amount of time, Open  vSwitch  assumes  the
              connection  has  been  broken and attempts to reconnect. Default is implementation-
              specific. A value of 0 disables inactivity probes.

     Asynchronous Messages:

       OpenFlow switches send certain messages to controllers spontanenously,  that  is,  not  in
       response  to  any  request  from  the controller. These messages are called ``asynchronous
       messages.’’ These columns allow asynchronous messages to be limited or disabled to  ensure
       the best use of network resources.

       enable_async_messages: optional boolean
              The   OpenFlow  protocol  enables  asynchronous  messages  at  time  of  connection
              establishment, which means that a controller  can  receive  asynchronous  messages,
              potentially  many  of them, even if it turns them off immediately after connecting.
              Set this column to false to change Open vSwitch behavior to  disable,  by  default,
              all  asynchronous  messages. The controller can use the NXT_SET_ASYNC_CONFIG Nicira
              extension to OpenFlow to turn on any messages that it does want to receive, if any.

     Controller Rate Limiting:

       A switch can forward packets to  a  controller  over  the  OpenFlow  protocol.  Forwarding
       packets  this  way  at  too  high  a rate can overwhelm a controller, frustrate use of the
       OpenFlow connection for other purposes, increase the latency of flow  setup,  and  use  an
       unreasonable  amount  of  bandwidth. Therefore, Open vSwitch supports limiting the rate of
       packet forwarding to a controller.

       There are two main reasons in OpenFlow for a packet to be sent to a controller: either the
       packet  ``misses’’  in the flow table, that is, there is no matching flow, or a flow table
       action says to send the packet to the controller. Open vSwitch limits  the  rate  of  each
       kind  of packet separately at the configured rate. Therefore, the actual rate that packets
       are sent to the controller can be up to twice the configured rate, when packets  are  sent
       for both reasons.

       This  feature  is  specific  to  forwarding packets over an OpenFlow connection. It is not
       general-purpose QoS.  See  the  QoS  table  for  quality  of  service  configuration,  and
       ingress_policing_rate in the Interface table for ingress policing configuration.

       controller_queue_size: optional integer, in range 1 to 512
              This  sets  the  maximum  size of the queue of packets that need to be sent to this
              OpenFlow controller. The value must be less than 512. If not  specified  the  queue
              size   is   limited   to   the   value   set   for  the  management  controller  in
              other_config:controller-queue-size if present or  100  packets  by  default.  Note:
              increasing the queue size might have a negative impact on latency.

       controller_rate_limit: optional integer, at least 100
              The  maximum  rate  at  which  the  switch  will  forward  packets  to the OpenFlow
              controller, in packets per second. If no  value  is  specified,  rate  limiting  is
              disabled.

       controller_burst_limit: optional integer, at least 25
              When  a  high  rate  triggers  rate-limiting,  Open  vSwitch  queues packets to the
              controller for each port and transmits them to the  controller  at  the  configured
              rate.  This  value limits the number of queued packets. Ports on a bridge share the
              packet queue fairly.

              This value has no effect unless controller_rate_limit is  configured.  The  current
              default  when  this value is not specified is one-quarter of controller_rate_limit,
              meaning that queuing can delay forwarding a packet to the controller by up  to  250
              ms.

     Controller Rate Limiting Statistics:

       These  values  report  the  effects  of  rate  limiting.  Their  values  are  relative  to
       establishment of the most recent OpenFlow connection, or since rate limiting was  enabled,
       whichever  happened  more recently. Each consists of two values, one with TYPE replaced by
       miss for rate limiting flow table misses, and the other with TYPE replaced by  action  for
       rate limiting packets sent by OpenFlow actions.

       These statistics are reported only when controller rate limiting is enabled.

       status : packet-in-TYPE-bypassed: optional string, containing an integer, at least 0
              Number  of  packets  sent  directly to the controller, without queuing, because the
              rate did not exceed the configured maximum.

       status : packet-in-TYPE-queued: optional string, containing an integer, at least 0
              Number of packets added to the queue to send later.

       status : packet-in-TYPE-dropped: optional string, containing an integer, at least 0
              Number of packets added to the queue that were later dropped due to overflow.  This
              value is less than or equal to status:packet-in-TYPE-queued.

       status : packet-in-TYPE-backlog: optional string, containing an integer, at least 0
              Number  of  packets  currently queued. The other statistics increase monotonically,
              but this one fluctuates between 0  and  the  controller_burst_limit  as  conditions
              change.

     Additional In-Band Configuration:

       These values are considered only in in-band control mode (see connection_mode).

       When  multiple controllers are configured on a single bridge, there should be only one set
       of unique values in these columns. If different  values  are  set  for  these  columns  in
       different controllers, the effect is unspecified.

       local_ip: optional string
              The IP address to configure on the local port, e.g. 192.168.0.123. If this value is
              unset, then local_netmask and local_gateway are ignored.

       local_netmask: optional string
              The IP netmask to configure on the local port, e.g. 255.255.255.0. If  local_ip  is
              set  but  this  value  is unset, then the default is chosen based on whether the IP
              address is class A, B, or C.

       local_gateway: optional string
              The IP address of the gateway to configure on the local port,  as  a  string,  e.g.
              192.168.0.1. Leave this column unset if this network has no gateway.

     Controller Status:

       is_connected: boolean
              true if currently connected to this controller, false otherwise.

       role: optional string, one of master, other, or slave
              The  level  of  authority  this  controller  has on the associated bridge. Possible
              values are:

              other  Allows the controller access to all OpenFlow features.

              master Equivalent to other, except that there may be at most one master  controller
                     at  a  time.  When  a  controller  configures itself as master, any existing
                     master is demoted to the slave role.

              slave  Allows the controller read-only access to  OpenFlow  features.  Attempts  to
                     modify  the  flow table will be rejected with an error. Slave controllers do
                     not receive  OFPT_PACKET_IN  or  OFPT_FLOW_REMOVED  messages,  but  they  do
                     receive OFPT_PORT_STATUS messages.

       status : last_error: optional string
              A human-readable description of the last error on the connection to the controller;
              i.e. strerror(errno). This key will exist only if an error has occurred.

       status : state: optional string, one of ACTIVE, BACKOFF, CONNECTING, IDLE, or VOID
              The state of the connection to the controller:

              VOID   Connection is disabled.

              BACKOFF
                     Attempting to reconnect at an increasing period.

              CONNECTING
                     Attempting to connect.

              ACTIVE Connected, remote host responsive.

              IDLE   Connection is idle. Waiting for response to keep-alive.

              These  values  may  change  in  the  future.  They  are  provided  only  for  human
              consumption.

       status : sec_since_connect: optional string, containing an integer, at least 0
              The  amount of time since this controller last successfully connected to the switch
              (in seconds). Value is empty if controller has never successfully connected.

       status : sec_since_disconnect: optional string, containing an integer, at least 1
              The amount of time since this controller last  disconnected  from  the  switch  (in
              seconds). Value is empty if controller has never disconnected.

     Connection Parameters:

       Additional configuration for a connection between the controller and the Open vSwitch.

       other_config : dscp: optional string, containing an integer
              The  Differentiated Service Code Point (DSCP) is specified using 6 bits in the Type
              of Service (TOS) field in the IP header. DSCP provides a mechanism to classify  the
              network traffic and provide Quality of Service (QoS) on IP networks. The DSCP value
              specified here is used when establishing the connection between the controller  and
              the  Open vSwitch. If no value is specified, a default value of 48 is chosen. Valid
              DSCP values must be in the range 0 to 63.

     Common Columns:

       The overall purpose of these columns is described under Common Columns at the beginning of
       this document.

       external_ids: map of string-string pairs

       other_config: map of string-string pairs

Manager TABLE

       Configuration for a database connection to an Open vSwitch database (OVSDB) client.

       This  table  primarily  configures  the Open vSwitch database (ovsdb-server), not the Open
       vSwitch  switch  (ovs-vswitchd).  The  switch  does  read  the  table  to  determine  what
       connections should be treated as in-band.

       The  Open  vSwitch  database server can initiate and maintain active connections to remote
       clients. It can also listen for database connections.

   Summary:
       Core Features:
         target                      string (must be unique within table)
         connection_mode             optional string, either in-band or out-of-band
       Client Failure Detection and Handling:
         max_backoff                 optional integer, at least 1,000
         inactivity_probe            optional integer
       Status:
         is_connected                boolean
         status : last_error         optional string
         status : state              optional string, one of ACTIVE, BACKOFF,  CONNECTING,  IDLE,
                                     or VOID
         status : sec_since_connect  optional string, containing an integer, at least 0
         status : sec_since_disconnect
                                     optional string, containing an integer, at least 0
         status : locks_held         optional string
         status : locks_waiting      optional string
         status : locks_lost         optional string
         status : n_connections      optional string, containing an integer, at least 2
         status : bound_port         optional string, containing an integer
       Connection Parameters:
         other_config : dscp         optional string, containing an integer
       Common Columns:
         external_ids                map of string-string pairs
         other_config                map of string-string pairs

   Details:
     Core Features:

       target: string (must be unique within table)
              Connection method for managers.

              The following connection methods are currently supported:

              ssl:host[:port]
                     The  specified SSL port on the host at the given host, which can either be a
                     DNS name (if built with unbound library) or an IP address. The ssl column in
                     the  Open_vSwitch  table  must  point to a valid SSL configuration when this
                     form is used.

                     If port is not specified, it defaults to 6640.

                     SSL support is an optional feature that is not always built as part of  Open
                     vSwitch.

              tcp:host[:port]
                     The  specified TCP port on the host at the given host, which can either be a
                     DNS name (if built with unbound library) or an IP address (IPv4 or IPv6). If
                     host is an IPv6 address, wrap it in square brackets, e.g. tcp:[::1]:6640.

                     If port is not specified, it defaults to 6640.

              pssl:[port][:host]
                     Listens for SSL connections on the specified TCP port. Specify 0 for port to
                     have the kernel automatically choose an available port. If host,  which  can
                     either  be  a  DNS name (if built with unbound library) or an IP address, is
                     specified, then connections are restricted  to  the  resolved  or  specified
                     local  IP address (either IPv4 or IPv6 address). If host is an IPv6 address,
                     wrap in square brackets, e.g. pssl:6640:[::1]. If host is not specified then
                     it  listens  only  on  IPv4  (but not IPv6) addresses. The ssl column in the
                     Open_vSwitch table must point to a valid SSL configuration when this form is
                     used.

                     If port is not specified, it defaults to 6640.

                     SSL  support is an optional feature that is not always built as part of Open
                     vSwitch.

              ptcp:[port][:host]
                     Listens for connections on the specified TCP port. Specify  0  for  port  to
                     have  the  kernel automatically choose an available port. If host, which can
                     either be a DNS name (if built with unbound library) or an  IP  address,  is
                     specified,  then  connections  are  restricted  to the resolved or specified
                     local IP address (either IPv4 or IPv6 address). If host is an IPv6  address,
                     wrap  it  in square brackets, e.g. ptcp:6640:[::1]. If host is not specified
                     then it listens only on IPv4 addresses.

                     If port is not specified, it defaults to 6640.

              When multiple managers are configured, the target values must be unique.  Duplicate
              target values yield unspecified results.

       connection_mode: optional string, either in-band or out-of-band
              If  it  is  specified,  this  setting  must  be  one  of the following strings that
              describes how Open vSwitch contacts this OVSDB client over the network:

              in-band
                     In this mode, this connection’s traffic travels over  a  bridge  managed  by
                     Open vSwitch. With this setting, Open vSwitch allows traffic to and from the
                     client regardless of the contents of the OpenFlow  flow  table.  (Otherwise,
                     Open  vSwitch  would  never be able to connect to the client, because it did
                     not have a flow to enable it.) This  is  the  most  common  connection  mode
                     because it is not necessary to maintain two independent networks.

              out-of-band
                     In this mode, the client’s traffic uses a control network separate from that
                     managed by Open vSwitch, that is, Open vSwitch does not use any of  its  own
                     network  devices to communicate with the client. The control network must be
                     configured separately, before or after ovs-vswitchd is started.

              If not specified, the default is implementation-specific.

     Client Failure Detection and Handling:

       max_backoff: optional integer, at least 1,000
              Maximum number of milliseconds to wait  between  connection  attempts.  Default  is
              implementation-specific.

       inactivity_probe: optional integer
              Maximum  number  of  milliseconds  of  idle time on connection to the client before
              sending an inactivity probe message. If Open vSwitch does not communicate with  the
              client  for the specified number of seconds, it will send a probe. If a response is
              not received for the same additional amount  of  time,  Open  vSwitch  assumes  the
              connection  has  been  broken and attempts to reconnect. Default is implementation-
              specific. A value of 0 disables inactivity probes.

     Status:

       Key-value pair of is_connected is always updated. Other  key-value  pairs  in  the  status
       columns may be updated depends on the target type.

       When target specifies a connection method that listens for inbound connections (e.g. ptcp:
       or punix:), both n_connections and is_connected may also be updated  while  the  remaining
       key-value pairs are omitted.

       On  the  other hand, when target specifies an outbound connection, all key-value pairs may
       be updated, except  the  above-mentioned  two  key-value  pairs  associated  with  inbound
       connection targets. They are omitted.

       is_connected: boolean
              true if currently connected to this manager, false otherwise.

       status : last_error: optional string
              A  human-readable  description  of the last error on the connection to the manager;
              i.e. strerror(errno). This key will exist only if an error has occurred.

       status : state: optional string, one of ACTIVE, BACKOFF, CONNECTING, IDLE, or VOID
              The state of the connection to the manager:

              VOID   Connection is disabled.

              BACKOFF
                     Attempting to reconnect at an increasing period.

              CONNECTING
                     Attempting to connect.

              ACTIVE Connected, remote host responsive.

              IDLE   Connection is idle. Waiting for response to keep-alive.

              These  values  may  change  in  the  future.  They  are  provided  only  for  human
              consumption.

       status : sec_since_connect: optional string, containing an integer, at least 0
              The  amount  of time since this manager last successfully connected to the database
              (in seconds). Value is empty if manager has never successfully connected.

       status : sec_since_disconnect: optional string, containing an integer, at least 0
              The amount of time since this manager  last  disconnected  from  the  database  (in
              seconds). Value is empty if manager has never disconnected.

       status : locks_held: optional string
              Space-separated list of the names of OVSDB locks that the connection holds. Omitted
              if the connection does not hold any locks.

       status : locks_waiting: optional string
              Space-separated list of the names of OVSDB locks that the connection  is  currently
              waiting to acquire. Omitted if the connection is not waiting for any locks.

       status : locks_lost: optional string
              Space-separated list of the names of OVSDB locks that the connection has had stolen
              by another OVSDB client. Omitted if no locks have been stolen from this connection.

       status : n_connections: optional string, containing an integer, at least 2
              When target specifies a connection method  that  listens  for  inbound  connections
              (e.g. ptcp: or pssl:) and more than one connection is actually active, the value is
              the number of active connections. Otherwise, this key-value pair is omitted.

       status : bound_port: optional string, containing an integer
              When target is ptcp: or pssl:, this is the TCP port on which the  OVSDB  server  is
              listening. (This is particularly useful when target specifies a port of 0, allowing
              the kernel to choose any available port.)

     Connection Parameters:

       Additional configuration for a  connection  between  the  manager  and  the  Open  vSwitch
       Database.

       other_config : dscp: optional string, containing an integer
              The  Differentiated Service Code Point (DSCP) is specified using 6 bits in the Type
              of Service (TOS) field in the IP header. DSCP provides a mechanism to classify  the
              network traffic and provide Quality of Service (QoS) on IP networks. The DSCP value
              specified here is used when establishing the connection between the manager and the
              Open vSwitch. If no value is specified, a default value of 48 is chosen. Valid DSCP
              values must be in the range 0 to 63.

     Common Columns:

       The overall purpose of these columns is described under Common Columns at the beginning of
       this document.

       external_ids: map of string-string pairs

       other_config: map of string-string pairs

NetFlow TABLE

       A NetFlow target. NetFlow is a protocol that exports a number of details about terminating
       IP flows, such as the principals involved and duration.

   Summary:
       targets                       set of 1 or more strings
       engine_id                     optional integer, in range 0 to 255
       engine_type                   optional integer, in range 0 to 255
       active_timeout                integer, at least -1
       add_id_to_interface           boolean
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       targets: set of 1 or more strings
              NetFlow targets in the form ip:port. The ip must be specified numerically, not as a
              DNS name.

       engine_id: optional integer, in range 0 to 255
              Engine ID to use in NetFlow messages. Defaults to datapath index if not specified.

       engine_type: optional integer, in range 0 to 255
              Engine  type  to  use  in  NetFlow  messages.  Defaults  to  datapath  index if not
              specified.

       active_timeout: integer, at least -1
              The interval at which NetFlow records are sent for flows that are still active,  in
              seconds. A value of 0 requests the default timeout (currently 600 seconds); a value
              of -1 disables active timeouts.

              The NetFlow passive timeout, for flows that become inactive, is  not  configurable.
              It  will  vary depending on the Open vSwitch version, the forms and contents of the
              OpenFlow flow tables, CPU and memory usage, and network activity. A typical passive
              timeout is about a second.

       add_id_to_interface: boolean
              If this column’s value is false, the ingress and egress interface fields of NetFlow
              flow records are derived from OpenFlow port numbers. When it is true,  the  7  most
              significant  bits  of these fields will be replaced by the least significant 7 bits
              of the engine id. This is useful because many  NetFlow  collectors  do  not  expect
              multiple  switches  to be sending messages from the same host, so they do not store
              the engine information which could be used to disambiguate the traffic.

              When this option is enabled, a maximum of 508 ports are supported.

     Common Columns:

       The overall purpose of these columns is described under Common Columns at the beginning of
       this document.

       external_ids: map of string-string pairs

Datapath TABLE

       Configuration for a datapath within Open_vSwitch.

       A datapath is responsible for providing the packet handling in Open vSwitch. There are two
       primary datapath implementations used  by  Open  vSwitch:  kernel  and  userspace.  Kernel
       datapath  implementations  are  available for Linux and Hyper-V, and selected as system in
       the datapath_type column of the Bridge table. The userspace datapath is used by  DPDK  and
       AF-XDP, and is selected as netdev in the datapath_type column of the Bridge table.

       A datapath of a particular type is shared by all the bridges that use that datapath. Thus,
       configurations applied to this table affect all bridges that use this datapath.

   Summary:
       datapath_version              string
       ct_zones                      map of integer-CT_Zone pairs, key in range 0 to 65,535
       Capabilities:
         capabilities : max_vlan_headers
                                     optional string, containing an integer, at least 0
         capabilities : recirc       optional string, either true or false
         Connection-Tracking Capabilities:
            capabilities : ct_state  optional string, either true or false
            capabilities : ct_state_nat
                                     optional string, either true or false
            capabilities : ct_zone   optional string, either true or false
            capabilities : ct_mark   optional string, either true or false
            capabilities : ct_label  optional string, either true or false
            capabilities : ct_orig_tuple
                                     optional string, either true or false
            capabilities : ct_orig_tuple6
                                     optional string, either true or false
         capabilities : masked_set_action
                                     optional string, either true or false
         capabilities : tnl_push_pop
                                     optional string, either true or false
         capabilities : ufid         optional string, either true or false
         capabilities : trunc        optional string, either true or false
         capabilities : nd_ext       optional string, either true or false
         Clone Actions:
            capabilities : clone     optional string, either true or false
            capabilities : sample_nesting
                                     optional string, containing an integer, at least 0
         capabilities : ct_eventmask
                                     optional string, either true or false
         capabilities : ct_clear     optional string, either true or false
         capabilities : max_hash_alg
                                     optional string, containing an integer, at least 0
         capabilities : check_pkt_len
                                     optional string, either true or false
         capabilities : ct_timeout   optional string, either true or false
         capabilities : explicit_drop_action
                                     optional string, either true or false
         capabilities : ct_zero_snat
                                     optional string, either true or false
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       datapath_version: string
              Reports the version number of  the  Open  vSwitch  datapath  in  use.  This  allows
              management  software  to  detect  and  report  discrepancies  between  Open vSwitch
              userspace and datapath  versions.  (The  ovs_version  column  in  the  Open_vSwitch
              reports  the  Open  vSwitch userspace version.) The version reported depends on the
              datapath in use:

              •      When the kernel module included in the Open vSwitch  source  tree  is  used,
                     this  column  reports  the  Open  vSwitch  version from which the module was
                     taken.

              •      When the kernel module that is part of the upstream Linux  kernel  is  used,
                     this column reports <unknown>.

              •      When the datapath is built into the ovs-vswitchd binary, this column reports
                     <built-in>. A built-in datapath is by definition the  same  version  as  the
                     rest of the Open vSwitch userspace.

              •      Other  datapaths  (such  as  the  Hyper-V  kernel datapath) currently report
                     <unknown>.

              A version discrepancy between ovs-vswitchd and the datapath in use is not  normally
              cause  for  alarm.  The  Open  vSwitch  kernel  datapaths for Linux and Hyper-V, in
              particular, are designed for maximum  inter-version  compatibility:  any  userspace
              version  works  with  with  any  kernel version. Some reasons do exist to insist on
              particular user/kernel pairings. First, newer kernel  versions  add  new  features,
              that  can  only  be  used  by  new-enough  userspace, e.g. VXLAN tunneling requires
              certain minimal userspace and kernel versions. Second, as an extension to the first
              reason,  some newer kernel versions add new features for enhancing performance that
              only new-enough userspace versions can take advantage of.

       ct_zones: map of integer-CT_Zone pairs, key in range 0 to 65,535
              Configuration for connection tracking zones. Each pair maps from a  zone  id  to  a
              configuration  for  that zone. Zone 0 applies to the default zone (ie, the one used
              if a zone is not specified in  connection  tracking-related  OpenFlow  matches  and
              actions).

     Capabilities:

       The  capabilities  column  reports  a  datapath’s  features.  For the netdev datapath, the
       capabilities are fixed for a given version of Open vSwitch because this datapath is  built
       into  the ovs-vswitchd binary. The Linux kernel and Windows and other datapaths, which are
       external to OVS userspace,  can  vary  in  version  and  capabilities  independently  from
       ovs-vswitchd.

       Some  of these features indicate whether higher-level Open vSwitch features are available.
       For  example,  OpenFlow  features  for  connection-tracking  are   available   only   when
       capabilities:ct_state  is true. A controller that wishes to determine whether a feature is
       supported could, therefore, consult the relevant capabilities in this table. However, as a
       general rule, it is better for a controller to try to use the higher-level feature and use
       the result as an indication of support, since the low-level capabilities are  more  likely
       to shift over time than the high-level features that rely on them.

       capabilities : max_vlan_headers: optional string, containing an integer, at least 0
              Number  of  802.1q  VLAN  headers  supported  by  the  datapath,  as  probed by the
              ovs-vswitchd slow path. If the datapath supports more VLAN headers  than  the  slow
              path,  this  reports the slow path’s limit. The value of other-config:vlan-limit in
              the Open_vSwitch table does not influence the number reported here.

       capabilities : recirc: optional string, either true or false
              If  this  is  true,  then  the  datapath   supports   recirculation,   specifically
              OVS_KEY_ATTR_RECIRC_ID.  Recirculation  enables  higher  performance  for  MPLS and
              active-active load balancing bonding modes.

     Connection-Tracking Capabilities:

       These capabilities are granular because Open vSwitch and its datapaths added  support  for
       connection  tracking  over  several  releases,  with features added individually over that
       time.

       capabilities : ct_state: optional string, either true or false
              If true, datapath supports OVS_KEY_ATTR_CT_STATE, which indicates support  for  the
              bits  in  the OpenFlow ct_state field (see ovs-fields(7)) other than snat and dnat,
              which have a separate capability.

              If this is false, the datapath does not support connection-tracking at all and  the
              remaining  connection-tracking capabilities should all be false. In this case, Open
              vSwitch will reject flows that match on the ct_state field or use the ct action.

       capabilities : ct_state_nat: optional string, either true or false
              If true, it means that the datapath  supports  the  snat  and  dnat  flags  in  the
              OpenFlow  ct_state  field.  The  ct_state  capability must be true for this to make
              sense.

              If false, Open vSwitch will reject flows that match on the snat  or  dnat  bits  in
              ct_state or use nat in the ct action.

       capabilities : ct_zone: optional string, either true or false
              If  true,  datapath  supports  OVS_KEY_ATTR_CT_ZONE. If false, Open vSwitch rejects
              flows that match on the ct_zone field or that specify a  nonzero  zone  or  a  zone
              field on the ct action.

       capabilities : ct_mark: optional string, either true or false
              If  true,  datapath  supports  OVS_KEY_ATTR_CT_MARK. If false, Open vSwitch rejects
              flows that match on the ct_mark field or that set ct_mark in the ct action.

       capabilities : ct_label: optional string, either true or false
              If true, datapath supports OVS_KEY_ATTR_CT_LABEL. If false,  Open  vSwitch  rejects
              flows that match on the ct_label field or that set ct_label in the ct action.

       capabilities : ct_orig_tuple: optional string, either true or false
              If  true, the datapath supports matching the 5-tuple from the connection’s original
              direction for IPv4 traffic. If false, Open vSwitch  rejects  flows  that  match  on
              ct_nw_src  or  ct_nw_dst,  that  use  the ct feature of the resubmit action, or the
              force keyword in the ct action. (The  latter  isn’t  tied  to  connection  tracking
              support  of  original  tuples  in any technical way. They are conflated because all
              current datapaths implemented the two features at the same time.)

              If this and capabilities:ct_orig_tuple6 are both false, Open vSwitch rejects  flows
              that match on ct_nw_proto, ct_tp_src, or ct_tp_dst.

       capabilities : ct_orig_tuple6: optional string, either true or false
              If  true, the datapath supports matching the 5-tuple from the connection’s original
              direction for IPv6 traffic. If false, Open vSwitch  rejects  flows  that  match  on
              ct_ipv6_src or ct_ipv6_dst.

       capabilities : masked_set_action: optional string, either true or false
              True  if  the  datapath supports masked data in OVS_ACTION_ATTR_SET actions. Masked
              data can improve performance by allowing megaflows to match on fewer fields.

       capabilities : tnl_push_pop: optional string, either true or false
              True if the datapath supports tnl_push and pop actions. This is a prerequisite  for
              a datapath to support native tunneling.

       capabilities : ufid: optional string, either true or false
              True   if   the   datapath   supports  OVS_FLOW_ATTR_UFID.  UFID  support  improves
              revalidation performance by transferring less data between the slow  path  and  the
              datapath.

       capabilities : trunc: optional string, either true or false
              True  if  the  datapath supports OVS_ACTION_ATTR_TRUNC action. If false, the output
              action with packet truncation requires every packet to be sent to the Open  vSwitch
              slow path, which is likely to make it too slow for mirroring traffic in bulk.

       capabilities : nd_ext: optional string, either true or false
              True  if  the  datapath  supports OVS_KEY_ATTR_ND_EXTENSIONS to match on ICMPv6 "ND
              reserved" and "ND option type" header fields. If false, the datapath reports  error
              if the feature is used.

     Clone Actions:

       When  Open vSwitch translates actions from OpenFlow into the datapath representation, some
       of the datapath actions may modify the packet  or  have  other  side  effects  that  later
       datapath actions can’t undo. The OpenFlow ct, meter, output with truncation, encap, decap,
       and dec_nsh_ttl actions fall into this category. Often, this  is  not  a  problem  because
       nothing later on needs the original packet.

       Such  actions  can, however, occur in circumstances where the translation does require the
       original packet. For example, an OpenFlow output action might direct a packet to  a  patch
       port,  which  might  in  turn  lead  to  a ct action that NATs the packet (which cannot be
       undone), and then afterward when control flow pops back across the patch port  some  other
       action might need to act on the original packet.

       Open  vSwitch  has  two different ways to implement this ``save and restore’’ via datapath
       actions. These capabilities indicate which one Open vSwitch will choose. When  neither  is
       available, Open vSwitch simply fails in situations that require this feature.

       capabilities : clone: optional string, either true or false
              True  if  the datapath supports OVS_ACTION_ATTR_CLONE action. This is the preferred
              option for saving and restoring packets, since it is intended for the purpose,  but
              old datapaths do not support it. Open vSwitch will use it whenever it is available.

              (The OpenFlow clone action does not always yield a OVS_ACTION_ATTR_CLONE action. It
              only does so when the datapath supports it and  the  clone  brackets  actions  that
              otherwise cannot be undone.)

       capabilities : sample_nesting: optional string, containing an integer, at least 0
              Maximum  level  of  nesting  allowed by OVS_ACTION_ATTR_SAMPLE action. Open vSwitch
              misuses this action for saving and restoring packets  when  the  datapath  supports
              more than 3 levels of nesting and OVS_ACTION_ATTR_CLONE is not available.

       capabilities : ct_eventmask: optional string, either true or false
              True    if    the    datapath’s    OVS_ACTION_ATTR_CT    action    implements   the
              OVS_CT_ATTR_EVENTMASK attribute. When this is true, Open  vSwitch  uses  the  event
              mask  feature  to limit the kinds of events reported to conntrack update listeners.
              When Open vSwitch doesn’t limit  the  event  mask,  listeners  receive  reports  of
              numerous  usually  unimportant events, such as TCP state machine changes, which can
              waste CPU time.

       capabilities : ct_clear: optional string, either true or false
              True if the  datapath  supports  OVS_ACTION_ATTR_CT_CLEAR  action.  If  false,  the
              OpenFlow ct_clear action has no effect on the datapath.

       capabilities : max_hash_alg: optional string, containing an integer, at least 0
              Highest supported dp_hash algorithm. This allows Open vSwitch to avoid requesting a
              packet hash that the datapath does not support.

       capabilities : check_pkt_len: optional string, either true or false
              True if the datapath supports OVS_ACTION_ATTR_CHECK_PKT_LEN. If false, Open vSwitch
              implements  the  check_pkt_larger  action  by sending every packet through the Open
              vSwitch slow path, which is likely to make it too  slow  for  handling  traffic  in
              bulk.

       capabilities : ct_timeout: optional string, either true or false
              True if the datapath supports OVS_CT_ATTR_TIMEOUT in the OVS_ACTION_ATTR_CT action.
              If false, Open vswitch  cannot  implement  timeout  policies  based  on  connection
              tracking zones, as configured through the CT_Timeout_Policy table.

       capabilities : explicit_drop_action: optional string, either true or false
              True  if the datapath supports OVS_ACTION_ATTR_DROP. If false, explicit drop action
              will not be sent to the datapath.

       capabilities : ct_zero_snat: optional string, either true or false
              True if the datapath supports all-zero SNAT. This is a special case if the  src  IP
              address  is  configured  as  all  0’s, i.e., nat(src=0.0.0.0). In this case, when a
              source port collision is detected during  the  commit,  the  source  port  will  be
              translated to an ephemeral port. If there is no collision, no SNAT is performed.

     Common Columns:

       The overall purpose of these columns is described under Common Columns at the beginning of
       this document.

       external_ids: map of string-string pairs

CT_Zone TABLE

       Connection tracking zone configuration

   Summary:
       timeout_policy                optional CT_Timeout_Policy
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       timeout_policy: optional CT_Timeout_Policy
              Connection tracking timeout policy for this  zone.  If  a  timeout  policy  is  not
              specified, it defaults to the timeout policy in the system.

     Common Columns:

       The overall purpose of these columns is described under Common Columns at the beginning of
       this document.

       external_ids: map of string-string pairs

CT_Timeout_Policy TABLE

       Connection tracking timeout policy configuration

   Summary:
       Timeouts:
         timeouts                    map  of  string-integer  pairs,  key  one   of   icmp_first,
                                     icmp_reply,   tcp_close,   tcp_close_wait,  tcp_established,
                                     tcp_fin_wait,  tcp_last_ack,  tcp_retransmit,  tcp_syn_recv,
                                     tcp_syn_sent2,   tcp_syn_sent,   tcp_time_wait,   tcp_unack,
                                     udp_first, udp_multiple, or udp_single, value in range 0  to
                                     4,294,967,295
         TCP Timeouts:
            timeouts : tcp_syn_sent  optional integer, in range 0 to 4,294,967,295
            timeouts : tcp_syn_recv  optional integer, in range 0 to 4,294,967,295
            timeouts : tcp_established
                                     optional integer, in range 0 to 4,294,967,295
            timeouts : tcp_fin_wait  optional integer, in range 0 to 4,294,967,295
            timeouts : tcp_close_wait
                                     optional integer, in range 0 to 4,294,967,295
            timeouts : tcp_last_ack  optional integer, in range 0 to 4,294,967,295
            timeouts : tcp_time_wait optional integer, in range 0 to 4,294,967,295
            timeouts : tcp_close     optional integer, in range 0 to 4,294,967,295
            timeouts : tcp_syn_sent2 optional integer, in range 0 to 4,294,967,295
            timeouts : tcp_retransmit
                                     optional integer, in range 0 to 4,294,967,295
            timeouts : tcp_unack     optional integer, in range 0 to 4,294,967,295
         UDP Timeouts:
            timeouts : udp_first     optional integer, in range 0 to 4,294,967,295
            timeouts : udp_single    optional integer, in range 0 to 4,294,967,295
            timeouts : udp_multiple  optional integer, in range 0 to 4,294,967,295
         ICMP Timeouts:
            timeouts : icmp_first    optional integer, in range 0 to 4,294,967,295
            timeouts : icmp_reply    optional integer, in range 0 to 4,294,967,295
       Common Columns:
         external_ids                map of string-string pairs

   Details:
     Timeouts:

       timeouts:  map  of  string-integer  pairs,  key  one of icmp_first, icmp_reply, tcp_close,
       tcp_close_wait, tcp_established, tcp_fin_wait, tcp_last_ack, tcp_retransmit, tcp_syn_recv,
       tcp_syn_sent2,   tcp_syn_sent,   tcp_time_wait,  tcp_unack,  udp_first,  udp_multiple,  or
       udp_single, value in range 0 to 4,294,967,295
              The timeouts column contains key-value pairs used to configure connection  tracking
              timeouts  in  a  datapath. Key-value pairs that are not supported by a datapath are
              ignored. The timeout value is in seconds.

     TCP Timeouts:

       timeouts : tcp_syn_sent: optional integer, in range 0 to 4,294,967,295
              The timeout for the connection after the first TCP SYN  packet  has  been  seen  by
              conntrack.

       timeouts : tcp_syn_recv: optional integer, in range 0 to 4,294,967,295
              The  timeout  of the connection after the first TCP SYN-ACK packet has been seen by
              conntrack.

       timeouts : tcp_established: optional integer, in range 0 to 4,294,967,295
              The timeout of the connection after the connection has been fully established.

       timeouts : tcp_fin_wait: optional integer, in range 0 to 4,294,967,295
              The timeout of the connection after the first TCP  FIN  packet  has  been  seen  by
              conntrack.

       timeouts : tcp_close_wait: optional integer, in range 0 to 4,294,967,295
              The timeout of the connection after the first TCP ACK packet has been seen after it
              receives TCP FIN packet. This  timeout  is  only  supported  by  the  Linux  kernel
              datapath.

       timeouts : tcp_last_ack: optional integer, in range 0 to 4,294,967,295
              The  timeout  of  the  connection after TCP FIN packets have been seen by conntrack
              from both directions. This timeout is only supported by the Linux kernel datapath.

       timeouts : tcp_time_wait: optional integer, in range 0 to 4,294,967,295
              The timeout of the connection after conntrack has seen the TCP ACK packet  for  the
              second TCP FIN packet.

       timeouts : tcp_close: optional integer, in range 0 to 4,294,967,295
              The  timeout  of  the  connection  after  the first TCP RST packet has been seen by
              conntrack.

       timeouts : tcp_syn_sent2: optional integer, in range 0 to 4,294,967,295
              The timeout of the connection when only a TCP SYN packet has been seen by conntrack
              from  both  directions  (simultaneous  open). This timeout is only supported by the
              Linux kernel datapath.

       timeouts : tcp_retransmit: optional integer, in range 0 to 4,294,967,295
              The  timeout  of  the  connection  when  it   exceeds   the   maximum   number   of
              retransmissions. This timeout is only supported by the Linux kernel datapath.

       timeouts : tcp_unack: optional integer, in range 0 to 4,294,967,295
              The timeout of the connection when non-SYN packets create an established connection
              in TCP loose tracking mode. This timeout is only  supported  by  the  Linux  kernel
              datapath.

     UDP Timeouts:

       timeouts : udp_first: optional integer, in range 0 to 4,294,967,295
              The  timeout  of  the  connection  after  the  first  UDP  packet  has been seen by
              conntrack. This timeout is only supported by the userspace datapath.

       timeouts : udp_single: optional integer, in range 0 to 4,294,967,295
              The timeout of the connection when conntrack only seen UDP packet from  the  source
              host, but the destination host has never sent one back.

       timeouts : udp_multiple: optional integer, in range 0 to 4,294,967,295
              The timeout of the connection when UDP packets have been seen in both directions.

     ICMP Timeouts:

       timeouts : icmp_first: optional integer, in range 0 to 4,294,967,295
              The  timeout  of  the  connection  after  the  first  ICMP  packet has been seen by
              conntrack.

       timeouts : icmp_reply: optional integer, in range 0 to 4,294,967,295
              The timeout of the connection after an ICMP error is replied in response to an ICMP
              packet. This timeout is only supported by the userspace datapath.

     Common Columns:

       The overall purpose of these columns is described under Common Columns at the beginning of
       this document.

       external_ids: map of string-string pairs

SSL TABLE

       SSL configuration for an Open_vSwitch.

   Summary:
       private_key                   string
       certificate                   string
       ca_cert                       string
       bootstrap_ca_cert             boolean
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       private_key: string
              Name of a PEM file containing the private key used as the switch’s identity for SSL
              connections to the controller.

       certificate: string
              Name  of  a  PEM file containing a certificate, signed by the certificate authority
              (CA) used by the controller and manager, that certifies the switch’s  private  key,
              identifying a trustworthy switch.

       ca_cert: string
              Name  of a PEM file containing the CA certificate used to verify that the switch is
              connected to a trustworthy controller.

       bootstrap_ca_cert: boolean
              If set to true, then Open vSwitch will attempt to obtain the  CA  certificate  from
              the controller on its first SSL connection and save it to the named PEM file. If it
              is successful, it will immediately drop the connection and reconnect, and from then
              on  all  SSL  connections  must  be authenticated by a certificate signed by the CA
              certificate  thus  obtained.  This  option  exposes  the  SSL   connection   to   a
              man-in-the-middle  attack  obtaining  the  initial  CA certificate. It may still be
              useful for bootstrapping.

     Common Columns:

       The overall purpose of these columns is described under Common Columns at the beginning of
       this document.

       external_ids: map of string-string pairs

sFlow TABLE

       A set of sFlow(R) targets. sFlow is a protocol for remote monitoring of switches.

   Summary:
       agent                         optional string
       header                        optional integer
       polling                       optional integer
       sampling                      optional integer
       targets                       set of 1 or more strings
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       agent: optional string
              Determines the agent address, that is, the IP address reported to collectors as the
              source of the sFlow data. It may be an IP address or the name of a network  device.
              In the latter case, the network device’s IP address is used,

              If not specified, the agent device is figured from the first target address and the
              routing table. If the routing table does not contain a route to the target, the  IP
              address defaults to the local_ip in the collector’s Controller.

              If an agent IP address cannot be determined, sFlow is disabled.

       header: optional integer
              Number of bytes of a sampled packet to send to the collector. If not specified, the
              default is 128 bytes.

       polling: optional integer
              Polling rate in seconds to send port statistics to the collector. If not specified,
              defaults to 30 seconds.

       sampling: optional integer
              Rate  at  which  packets  should  be  sampled  and  sent  to  the collector. If not
              specified, defaults to 400, which means one out of 400 packets, on average, will be
              sent to the collector.

       targets: set of 1 or more strings
              sFlow targets in the form ip:port.

     Common Columns:

       The overall purpose of these columns is described under Common Columns at the beginning of
       this document.

       external_ids: map of string-string pairs

IPFIX TABLE

       Configuration for sending packets to IPFIX collectors.

       IPFIX is a protocol that exports a number of details about flows. The IPFIX implementation
       in  Open  vSwitch  samples  packets at a configurable rate, extracts flow information from
       those packets, optionally caches and aggregates the flow information, and sends the result
       to one or more collectors.

       IPFIX in Open vSwitch can be configured two different ways:

              •      With per-bridge sampling, Open vSwitch performs IPFIX sampling automatically
                     on all packets that pass through a bridge. To configure per-bridge sampling,
                     create  an  IPFIX  record and point a Bridge table’s ipfix column to it. The
                     Flow_Sample_Collector_Set table is not used for per-bridge sampling.

              •      With flow-based sampling, sample actions in the OpenFlow  flow  table  drive
                     IPFIX sampling. See ovs-actions(7) for a description of the sample action.

                     Flow-based  sampling  also  requires  database configuration: create a IPFIX
                     record    that    describes    the     IPFIX     configuration     and     a
                     Flow_Sample_Collector_Set  record that points to the Bridge whose flow table
                     holds the sample actions and to IPFIX record. The ipfix in the Bridge  table
                     is not used for flow-based sampling.

   Summary:
       targets                       set of strings
       cache_active_timeout          optional integer, in range 0 to 4,200
       cache_max_flows               optional integer, in range 0 to 4,294,967,295
       other_config : enable-tunnel-sampling
                                     optional string, either true or false
       other_config : virtual_obs_id optional string
       Per-Bridge Sampling:
         sampling                    optional integer, in range 1 to 4,294,967,295
         obs_domain_id               optional integer, in range 0 to 4,294,967,295
         obs_point_id                optional integer, in range 0 to 4,294,967,295
         other_config : enable-input-sampling
                                     optional string, either true or false
         other_config : enable-output-sampling
                                     optional string, either true or false
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       targets: set of strings
              IPFIX target collectors in the form ip:port.

       cache_active_timeout: optional integer, in range 0 to 4,200
              The  maximum  period  in  seconds  for  which  an  IPFIX  flow record is cached and
              aggregated before being sent. If not specified, defaults to 0.  If  0,  caching  is
              disabled.

       cache_max_flows: optional integer, in range 0 to 4,294,967,295
              The  maximum  number  of  IPFIX  flow  records that can be cached at a time. If not
              specified, defaults to 0. If 0, caching is disabled.

       other_config : enable-tunnel-sampling: optional string, either true or false
              Set to true to enable sampling and reporting tunnel header 7-tuples in  IPFIX  flow
              records. Tunnel sampling is enabled by default.

              The following enterprise entities report the sampled tunnel info:

              tunnelType:
                     ID: 891, and enterprise ID 6876 (VMware).

                     type: unsigned 8-bit integer.

                     data type semantics: identifier.

                     description: Identifier of the layer 2 network overlay network encapsulation
                     type: 0x01 VxLAN, 0x02 GRE, 0x03 LISP, 0x07 GENEVE.

              tunnelKey:
                     ID: 892, and enterprise ID 6876 (VMware).

                     type: variable-length octetarray.

                     data type semantics: identifier.

                     description: Key which is used for identifying an  individual  traffic  flow
                     within  a VxLAN (24-bit VNI), GENEVE (24-bit VNI), GRE (32-bit key), or LISP
                     (24-bit instance ID) tunnel. The key is encoded in this octetarray as a  3-,
                     4-, or 8-byte integer ID in network byte order.

              tunnelSourceIPv4Address:
                     ID: 893, and enterprise ID 6876 (VMware).

                     type: unsigned 32-bit integer.

                     data type semantics: identifier.

                     description: The IPv4 source address in the tunnel IP packet header.

              tunnelDestinationIPv4Address:
                     ID: 894, and enterprise ID 6876 (VMware).

                     type: unsigned 32-bit integer.

                     data type semantics: identifier.

                     description: The IPv4 destination address in the tunnel IP packet header.

              tunnelProtocolIdentifier:
                     ID: 895, and enterprise ID 6876 (VMware).

                     type: unsigned 8-bit integer.

                     data type semantics: identifier.

                     description:  The  value  of  the  protocol  number  in the tunnel IP packet
                     header. The protocol number identifies the tunnel IP packet payload type.

              tunnelSourceTransportPort:
                     ID: 896, and enterprise ID 6876 (VMware).

                     type: unsigned 16-bit integer.

                     data type semantics: identifier.

                     description: The source port identifier in the tunnel transport header.  For
                     the  transport  protocols UDP, TCP, and SCTP, this is the source port number
                     given in the respective header.

              tunnelDestinationTransportPort:
                     ID: 897, and enterprise ID 6876 (VMware).

                     type: unsigned 16-bit integer.

                     data type semantics: identifier.

                     description: The destination port identifier in the tunnel transport header.
                     For the transport protocols UDP, TCP, and SCTP, this is the destination port
                     number given in the respective header.

              Before Open vSwitch 2.5.90, other_config:enable-tunnel-sampling was only  supported
              with  per-bridge  sampling,  and  ignored  otherwise. Open vSwitch 2.5.90 and later
              support other_config:enable-tunnel-sampling for per-bridge and per-flow sampling.

       other_config : virtual_obs_id: optional string
              A string that accompanies each IPFIX flow record.  Its  intended  use  is  for  the
              ``virtual  observation  ID,’’  an identifier of a virtual observation point that is
              locally unique in a virtual network. It describes a location in the virtual network
              where  IP  packets  can  be  observed.  The  maximum  length  is  254 bytes. If not
              specified, the field is omitted from the IPFIX flow record.

              The following enterprise entity reports the specified virtual observation ID:

              virtualObsID:
                     ID: 898, and enterprise ID 6876 (VMware).

                     type: variable-length string.

                     data type semantics: identifier.

                     description: A virtual observation domain ID that is  locally  unique  in  a
                     virtual network.

              This feature was introduced in Open vSwitch 2.5.90.

     Per-Bridge Sampling:

       These  values  affect  only  per-bridge  sampling.  See  above  for  a  description of the
       differences between per-bridge and flow-based sampling.

       sampling: optional integer, in range 1 to 4,294,967,295
              The rate at which packets should be sampled and sent to each target  collector.  If
              not  specified,  defaults  to  400, which means one out of 400 packets, on average,
              will be sent to each target collector.

       obs_domain_id: optional integer, in range 0 to 4,294,967,295
              The IPFIX Observation Domain ID sent  in  each  IPFIX  packet.  If  not  specified,
              defaults to 0.

       obs_point_id: optional integer, in range 0 to 4,294,967,295
              The  IPFIX  Observation  Point ID sent in each IPFIX flow record. If not specified,
              defaults to 0.

       other_config : enable-input-sampling: optional string, either true or false
              By default, Open vSwitch samples and reports flows at bridge port  input  in  IPFIX
              flow records. Set this column to false to disable input sampling.

       other_config : enable-output-sampling: optional string, either true or false
              By  default,  Open vSwitch samples and reports flows at bridge port output in IPFIX
              flow records. Set this column to false to disable output sampling.

     Common Columns:

       The overall purpose of these columns is described under Common Columns at the beginning of
       this document.

       external_ids: map of string-string pairs

Flow_Sample_Collector_Set TABLE

       A  set  of  IPFIX  collectors of packet samples generated by OpenFlow sample actions. This
       table is used only for IPFIX flow-based sampling, not for  per-bridge  sampling  (see  the
       IPFIX table for a description of the two forms).

   Summary:
       id                            integer, in range 0 to 4,294,967,295
       bridge                        Bridge
       ipfix                         optional IPFIX
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       id: integer, in range 0 to 4,294,967,295
              The  ID of this collector set, unique among the bridge’s collector sets, to be used
              as the collector_set_id in OpenFlow sample actions.

       bridge: Bridge
              The bridge into which OpenFlow sample actions can be added to send  packet  samples
              to this set of IPFIX collectors.

       ipfix: optional IPFIX
              Configuration  of  the  set of IPFIX collectors to send one flow record per sampled
              packet to.

     Common Columns:

       The overall purpose of these columns is described under Common Columns at the beginning of
       this document.

       external_ids: map of string-string pairs

AutoAttach TABLE

       Auto  Attach  configuration  within  a  bridge.  The  IETF Auto-Attach SPBM draft standard
       describes a compact method of using IEEE 802.1AB  Link  Layer  Discovery  Protocol  (LLDP)
       together  with a IEEE 802.1aq Shortest Path Bridging (SPB) network to automatically attach
       network devices to individual services in a SPB network.  The  intent  here  is  to  allow
       network applications and devices using OVS to be able to easily take advantage of features
       offered by industry standard SPB networks.

       Auto Attach (AA) uses LLDP to communicate between a directly connected Auto Attach  Client
       (AAC)  and  Auto  Attach  Server (AAS). The LLDP protocol is extended to add two new Type-
       Length-Value tuples (TLVs). The first new TLV supports the ongoing discovery  of  directly
       connected  AA  correspondents. Auto Attach operates by regularly transmitting AA discovery
       TLVs between the AA client and AA server. By exchanging these discovery messages, both the
       AAC  and  AAS  learn  the  system  name  and  system description of their peer. In the OVS
       context, OVS operates as the AA client and the AA server resides on a switch at  the  edge
       of the SPB network.

       Once  AA  discovery  has  been  completed  the AAC then uses the second new TLV to deliver
       identifier mappings from the AAC to the AAS. A  primary  feature  of  Auto  Attach  is  to
       facilitate  the  mapping of VLANs defined outside the SPB network onto service ids (ISIDs)
       defined within the SPM network. By doing so individual external VLANs can be  mapped  onto
       specific  SPB  network  services.  These  VLAN  id  to ISID mappings can be configured and
       managed locally using new options added to the ovs-vsctl command.

       The Auto Attach OVS feature does not provide a full implementation of the  LLDP  protocol.
       Support  for the mandatory TLVs as defined by the LLDP standard and support for the AA TLV
       extensions is provided. LLDP protocol support in OVS can be enabled or disabled on a  port
       by port basis. LLDP support is disabled by default.

   Summary:
       system_name                   string
       system_description            string
       mappings                      map  of integer-integer pairs, key in range 0 to 16,777,215,
                                     value in range 0 to 4,095

   Details:
       system_name: string
              The system_name string is exported in LLDP messages. It  should  uniquely  identify
              the bridge in the network.

       system_description: string
              The  system_description string is exported in LLDP messages. It should describe the
              type of software and hardware.

       mappings: map of integer-integer pairs, key in range 0 to 16,777,215, value in range 0  to
       4,095
              A mapping from SPB network Individual Service Identifier (ISID) to VLAN id.