ovs-test(8) — Linux manual page


OVS-TEST(8)                   Open vSwitch                   OVS-TEST(8)

NAME         top

       ovs-test - Check Linux drivers for performance, vlan and L3
       tunneling problems

SYNOPSIS         top

       ovs-test -s port

       ovs-test -c server1 server2 [-b targetbandwidth] [-i
       testinterval] [-d]
              [-l vlantag] [-t tunnelmodes]

DESCRIPTION         top

       The ovs-test program may be used to check for problems sending
       802.1Q or GRE traffic that Open vSwitch may uncover. These
       problems, for example, 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 IP addresses on server1 and server2 for interfaces you
       intended to test. These interfaces could also be already
       configured OVS bridges that have a physical interface attached to
       them. Then, on one of the nodes, run ovs-test in server mode and
       on the other node run it in client mode. The client will connect
       to ovs-test server and schedule tests between both of them. The
       ovs-test client will perform UDP and TCP tests.

       UDP tests can report packet loss and achieved bandwidth for
       various datagram sizes. By default target bandwidth for UDP tests
       is 1Mbit/s.

       TCP tests report only achieved bandwidth, because kernel TCP
       stack takes care of flow control and packet loss. TCP tests are
       essential to detect potential TSO related issues.

       To determine whether Open vSwitch is encountering any problems,
       the user must compare packet loss and achieved bandwidth in a
       setup where traffic is being directly sent and in one where it is
       not. If in the 802.1Q or L3 tunneled tests both ovs-test
       processes are unable to communicate or the achieved bandwidth is
       much lower compared to direct setup, then, most likely, Open
       vSwitch has encountered a pre-existing kernel or driver bug.

       Some examples of the types of problems that may be encountered

       • 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-test client will connect to two ovs-test servers
              and will ask them to exchange test traffic. It is also
              possible to spawn an ovs-test server automatically from
              the client.

       Server Mode
              To conduct tests, two ovs-test servers must be running on
              two different hosts where the client can connect. The
              actual test traffic is exchanged only between both
              ovs-test servers. It is recommended that both servers have
              their IP addresses in the same subnet, otherwise one would
              have to make sure that routing is set up correctly.

OPTIONS         top

       -s <port>, --server <port>
              Run in server mode and wait for the client to establish
              XML RPC Control Connection on this TCP port. It is
              recommended to have ethtool(8) installed on the server so
              that it could retrieve information about the NIC driver.

       -c <server1> <server2>, --client <server1> <server2>
              Run in client mode and schedule tests between server1 and
              server2, where each server must be given in the following


              The OuterIP must be already assigned to the physical
              interface which is going to be tested. This is the IP
              address where client will try to establish XML RPC
              connection. If OuterIP is then client will
              automatically spawn a local instance of ovs-test server.
              OuterPort is TCP port where server is listening for
              incoming XML/RPC control connections to schedule tests (by
              default it is 15531). The ovs-test will automatically
              assign InnerIP[/Mask] to the interfaces that will be
              created on the fly for testing purposes. It is important
              that InnerIP[/Mask] does not interfere with already
              existing IP addresses on both ovs-test servers and client.
              InnerPort is port which will be used by server to listen
              for test traffic that will be encapsulated (by default it
              is 15532).

       -b <targetbandwidth>, --bandwidth <targetbandwidth>
              Target bandwidth for UDP tests. The targetbandwidth must
              be given in bits per second. It is possible to use postfix
              M or K to alter the target bandwidth magnitude.

       -i <testinterval>, --interval <testinterval>
              How long each test should run. By default 5 seconds.

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

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

       The following test modes are supported by ovs-test. It is
       possible to combine multiple of them in a single ovs-test

       -d, --direct
              Perform direct tests between both OuterIP addresses. These
              tests could be used as a reference to compare 802.1Q or L3
              tunneling test results.

       -l <vlantag>, --vlan-tag <vlantag>
              Perform 802.1Q tests between both servers. These tests
              will create a temporary OVS bridge, if necessary, and
              attach a VLAN tagged port to it for testing purposes.

       -t <tunnelmodes>, --tunnel-modes <tunnelmodes>
              Perform L3 tunneling tests. The given argument is a comma
              sepa‐ rated string that specifies all the L3 tunnel modes
              that should be tested (e.g.  gre). The L3 tunnels are
              terminated on interface that has the OuterIP address

EXAMPLES         top

       On host start ovs-test in server mode:

          ovs-test -s 15531

       On host start ovs-test in client mode and do direct, VLAN
       and GRE tests between both nodes:

          ovs-test -c,, -d -l 123 -t

SEE ALSO         top

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

AUTHOR         top

       The Open vSwitch Development Community

COPYRIGHT         top

       2016-2021, The Open vSwitch Development Community

COLOPHON         top

       This page is part of the Open vSwitch (a distributed virtual
       multilayer switch) project.  Information about the project can be
       found at ⟨http://openvswitch.org/⟩.  If you have a bug report for
       this manual page, send it to bugs@openvswitch.org.  This page was
       obtained from the project's upstream Git repository
       ⟨https://github.com/openvswitch/ovs.git⟩ on 2023-12-22.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2023-12-21.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

3.2.90                        Dec 22, 2023                   OVS-TEST(8)

Pages that refer to this page: ovs-l3ping(8)