NAME

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

SYNOPSIS

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

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
          ip addr add 1.2.3.4/8 dev vlan-br-tag
          ip link set vlan-br-tag up

       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, ethtool(8), uname(1)

AUTHOR

       The Open vSwitch Development Community

COPYRIGHT

       2016-2023, The Open vSwitch Development Community