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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLES | SEE ALSO | AUTHOR | COPYRIGHT | COLOPHON |
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OVS-VLAN-TEST(8) Open vSwitch OVS-VLAN-TEST(8)
ovs-vlan-test - Check Linux drivers for problems with vlan traffic
ovs-vlan-test [-s | –server] control_ip vlan_ip
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.
-s, --server
Run in server mode.
-h, --help
Prints a brief help message to the console.
-V, --version
Prints version information to the console.
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
ovs-vswitchd(8), ovs-ofctl(8), ovs-vsctl(8), ovs-test, ethtool(8),
uname(1)
The Open vSwitch Development Community
2016-2024, The Open vSwitch Development Community
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 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-07-31.) 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
man-pages@man7.org
3.6.90 Aug 09, 2025 OVS-VLAN-TEST(8)
Pages that refer to this page: ovs-l3ping(8)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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