ovs-vlan-test(1)						Open vSwitch Manual						  ovs-vlan-test(1)

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 prob-
       lems 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:

       o      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.

       o      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.

       o      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.

       o      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 connec-
       tions 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)

Open vSwitch							   December 2010						  ovs-vlan-test(1)