[ovs-dev] mpls and vlan qinq

KerurR at telekom.de KerurR at telekom.de
Tue Mar 20 17:19:09 UTC 2012


Please see inline <rk>

On Mon, Mar 19, 2012 at 2:14 PM,  <KerurR at telekom.de> wrote:
> When kernel >= 2.6.37 and vlan_tpid = 0x88a8, in function netdev_send,
> __vlan_put_tag present in OVS tree is not executed since
> dev_supports_vlan_tx returns true. It goes through the path of
> dev_queue_xmit which eventually calls __vlan_put_tag present in the kernel
> source tree. Need some inputs here. For kernel < 2.6.37, things work fine. I
> have verified it on 2.6.32 Centos 6.2 system.

Are you actually seeing a problem?  What you are describing sounds
like correct behavior - OVS is just emulating behavior of new kernels
in that code vport-netdev.c, so on those kernels we don't need to do
it and dev_queue_xmit() can take care of it if necessary.

Note that __vlan_put_tag() always uses a TPID of 0x8100, so you can't
use it for other values.

<rk> yes for vlan qinq, when new tag need to be pushed on an existing vlan tagged packet, the outer tag can be 0x8100 or 0x88a8 and it won't work for kernel >= 2.6.37 if outer tag is 0x88a8.

Thanks
Ravi



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