NAME

       ovs-vlan-test - check Linux drivers for problems with vlan traffic

SYNOPSIS

       ovs-vlan-test [-s | --server] control_ip vlan_ip

       Common options:
              [-h | --help] [-V | --version]

DESCRIPTION

       The  ovs-vlan-test  utility  has some limitations, for example, it does not use TCP in its
       tests. Also it does not take into account MTU to detect potential edge cases. To  overcome
       those  limitations  a  new  tool was developed - ovs-test. ovs-test is currently supported
       only on Debian so, if possible try to use that on instead of ovs-vlan-test.

       The ovs-vlan-test program may be used to check for problems sending 802.1Q  traffic  which
       may occur when running Open vSwitch. These problems can occur when Open vSwitch is used to
       send 802.1Q traffic through physical interfaces running certain drivers of  certain  Linux
       kernel  versions.  To  run  a test, configure Open vSwitch to tag traffic originating from
       vlan_ip and forward it out the target interface. Then run the ovs-vlan-test in client mode
       connecting  to  an  ovs-vlan-test  server.   ovs-vlan-test will display "OK" if it did not
       detect problems.

       Some examples of the types of problems that may be encountered are:

       •      When NICs use VLAN stripping on receive they must pass a pointer  to  a  vlan_group
              when reporting the stripped tag to the networking core.  If no vlan_group is in use
              then some drivers just drop the extracted tag.  Drivers are supposed to only enable
              stripping if a vlan_group is registered but not all of them do that.

       •      On  receive,  some  drivers handle priority tagged packets specially and don't pass
              the tag onto the network stack at all, so Open vSwitch never has a  chance  to  see
              it.

       •      Some  drivers  size their receive buffers based on whether a vlan_group is enabled,
              meaning that a maximum size packet with a VLAN tag will not fit if no vlan_group is
              configured.

       •      On  transmit,  some  drivers  expect  that  VLAN acceleration will be used if it is
              available, which can only be done if a vlan_group is configured.  In  these  cases,
              the  driver may fail to parse the packet and correctly setup checksum offloading or
              TSO.

   Client Mode
       An ovs-vlan-test client may be run on a host to check for VLAN connectivity problems.  The
       client  must be able to establish HTTP connections with an ovs-vlan-test server located at
       the specified control_ip address.  UDP traffic sourced at vlan_ip  should  be  tagged  and
       directed out the interface whose connectivity is being tested.

   Server Mode
       To conduct tests, an ovs-vlan-test server must be running on a host known not to have VLAN
       connectivity problems.  The server must have a control_ip  on  a  non-VLAN  network  which
       clients  can  establish  connectivity with.  It must also have a vlan_ip address on a VLAN
       network which clients will use to test their VLAN connectivity.  Multiple clients may test
       against a single ovs-vlan-test server concurrently.

OPTIONS

       -s
       --server
              Run in server mode.

       -h
       --help Prints a brief help message to the console.

       -V
       --version
              Prints version information to the console.

EXAMPLES

       Display the Linux kernel version and driver of eth1.

              uname -r

              ethtool -i eth1

       Set up a bridge which forwards traffic originating from 1.2.3.4 out eth1 with VLAN tag 10.

              ovs-vsctl -- add-br vlan-br \

              -- add-port vlan-br eth1 \

              -- add-port vlan-br vlan-br-tag tag=10 \

              -- set Interface vlan-br-tag type=internal

              ifconfig vlan-br-tag up 1.2.3.4

       Run an ovs-vlan-test server listening for client control traffic on 172.16.0.142 port 8080
       and VLAN traffic on the default port of 1.2.3.3.

              ovs-vlan-test -s 172.16.0.142:8080 1.2.3.3

       Run an ovs-vlan-test client with a control server located at 172.16.0.142 port 8080 and  a
       local VLAN ip of 1.2.3.4.

              ovs-vlan-test 172.16.0.142:8080 1.2.3.4

SEE ALSO

       ovs-vswitchd(8), ovs-ofctl(8), ovs-vsctl(8), ovs-test(8), ethtool(8), uname(1)