Linux Ethernet Bridging - Aug 2013 - [Bridge] Can linux kernel bridge forward 802.1q tagged vlan packets?

On Thu, 22 Aug 2013 23:49:41 +0200
Marek Kierdelewicz <marek at piasta.pl> wrote:
> Hi,
> 
> >My general idea is to bridge tagged vlan packets from a physical
> >interface (intel) to a virtual interface (virtio in qemu) and not
> >losing the tags, so the qemu guest can use vconfig and friends to get
> >some vlan interfaces. Is this possible and are there any additional
> >steps necessary besides the usual bridge configuration?
> 
> I'm using this setup with KVM virtualization (Qemu's successor). It
> didn't work with default nic type for guest (realtek I think) as 802.1q
> tags were not preserved properly in one of the directions. I don't
> remember specifics. Anyway using e1000 driver instead of default fixed
> it. Works like a charm.
KVM e1000 Vnic doesn't do VLAN offloading at least in my experience.
Virtio works fine.

On Thu, 22 Aug 2013 15:19:41 -0700
Stephen Hemminger <stephen at networkplumber.org> wrote:
> On Thu, 22 Aug 2013 23:49:41 +0200
> Marek Kierdelewicz <marek at piasta.pl> wrote:
> 
> > Hi,
> > 
> > >My general idea is to bridge tagged vlan packets from a physical
> > >interface (intel) to a virtual interface (virtio in qemu) and not
> > >losing the tags, so the qemu guest can use vconfig and friends to
get
> > >some vlan interfaces. Is this possible and are there any
additional
> > >steps necessary besides the usual bridge configuration?
> > 
> > I'm using this setup with KVM virtualization (Qemu's
successor). It
> > didn't work with default nic type for guest (realtek I think) as
802.1q
> > tags were not preserved properly in one of the directions. I don't
> > remember specifics. Anyway using e1000 driver instead of default fixed
> > it. Works like a charm.
> 
> KVM e1000 Vnic doesn't do VLAN offloading at least in my experience.
> Virtio works fine.
Ok guys, here is one of the major questions in this issue:

How did you manage to convince the _host_ interface driver (in my setup
"igb"
from intel) to get the vlan tagged packets from the LAN port. igb has a vlan
filter function built in and reads _no_ tagged packets at all if the driver
does not tell it to. And in case of "up-ing" the interface for
attachment to a
bridge it does not configure this vlan filter.
How is this expected to work?

-- 
Regards,
Stephan

Adding Carolyn Wyborny (igb maintainer) and Mitch Williams (igbvf maintainer)...

On Thu, Aug 22, 2013 at 9:22 PM, Stephan von Krawczynski
<skraw@ithnet.com> wrote:
> On Thu, 22 Aug 2013 15:19:41 -0700
> Stephen Hemminger <stephen@networkplumber.org> wrote:
>
>> On Thu, 22 Aug 2013 23:49:41 +0200
>> Marek Kierdelewicz <marek@piasta.pl> wrote:
>>
>> > Hi,
>> >
>> > >My general idea is to bridge tagged vlan packets from a
physical
>> > >interface (intel) to a virtual interface (virtio in qemu) and
not
>> > >losing the tags, so the qemu guest can use vconfig and friends
to get
>> > >some vlan interfaces. Is this possible and are there any
additional
>> > >steps necessary besides the usual bridge configuration?
>> >
>> > I''m using this setup with KVM virtualization
(Qemu''s successor). It
>> > didn''t work with default nic type for guest (realtek I
think) as 802.1q
>> > tags were not preserved properly in one of the directions. I
don''t
>> > remember specifics. Anyway using e1000 driver instead of default
fixed
>> > it. Works like a charm.
>>
>> KVM e1000 Vnic doesn''t do VLAN offloading at least in my
experience.
>> Virtio works fine.
>
> Ok guys, here is one of the major questions in this issue:
>
> How did you manage to convince the _host_ interface driver (in my setup
"igb"
> from intel) to get the vlan tagged packets from the LAN port. igb has a
vlan
> filter function built in and reads _no_ tagged packets at all if the driver
> does not tell it to. And in case of "up-ing" the interface for
attachment to a
> bridge it does not configure this vlan filter.
> How is this expected to work?
>
> --
> Regards,
> Stephan
>
> --
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-- 
Cheers,
Jeff