Ubuntu Manpage: ovs-test - check Linux drivers for performance, vlan and L3 tunneling problems

Provided by: openvswitch-test_2.5.9-0ubuntu0.16.04.3_all

NAME

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

SYNOPSIS

       ovs-test -s port

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

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

DESCRIPTION

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 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-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

-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 format -
OuterIP[:OuterPort],InnerIP[/Mask][:InnerPort]. 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
127.0.0.1 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.

Test Modes

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

       -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 separated 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 assigned.

EXAMPLES