* Problem with igb and vlans in 2.6.38-rc4
@ 2011-02-10 17:57 Ben Greear
2011-02-10 20:51 ` Ben Greear
0 siblings, 1 reply; 2+ messages in thread
From: Ben Greear @ 2011-02-10 17:57 UTC (permalink / raw)
To: netdev
We have a user-space app that uses packet-sockets to grab and send
Ethernet frames (basically a user-space bridge).
This has stopped working for VLANs unless we set the physical
port MTU to be vlan-MTU + 4 (ie, 1504 for standard MTU size vlan frames).
I think this started post 2.6.34 kernel..but not exactly sure at this
time.
The test setup is essentially:
client -- vlan 5 -- [ eth4 {software-bridge} eth3 ] -- vlan 5 -- server
The software bridge machine has no VLANs enabled..it is supposed to just
read Ethernet frames from one port and xmit out the other.
The bridge machine sees rx-length errors, and if only one port is
set to 1504, the other shows xmit errors (since it doesn't like sending
a frame 4 bytes larger than MTU probably).
This used to work, and I'm hoping this change wasn't done on purpose.
Thanks,
Ben
--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc http://www.candelatech.com
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: Problem with igb and vlans in 2.6.38-rc4
2011-02-10 17:57 Problem with igb and vlans in 2.6.38-rc4 Ben Greear
@ 2011-02-10 20:51 ` Ben Greear
0 siblings, 0 replies; 2+ messages in thread
From: Ben Greear @ 2011-02-10 20:51 UTC (permalink / raw)
To: netdev
On 02/10/2011 09:57 AM, Ben Greear wrote:
>
> We have a user-space app that uses packet-sockets to grab and send
> Ethernet frames (basically a user-space bridge).
FYI: I'll post some patches for comment soon..seems
I have it working now, just need to clean them up and
eat lunch :)
Thanks,
Ben
>
> This has stopped working for VLANs unless we set the physical
> port MTU to be vlan-MTU + 4 (ie, 1504 for standard MTU size vlan frames).
> I think this started post 2.6.34 kernel..but not exactly sure at this
> time.
>
> The test setup is essentially:
>
> client -- vlan 5 -- [ eth4 {software-bridge} eth3 ] -- vlan 5 -- server
>
> The software bridge machine has no VLANs enabled..it is supposed to just
> read Ethernet frames from one port and xmit out the other.
>
> The bridge machine sees rx-length errors, and if only one port is
> set to 1504, the other shows xmit errors (since it doesn't like sending
> a frame 4 bytes larger than MTU probably).
>
> This used to work, and I'm hoping this change wasn't done on purpose.
>
> Thanks,
> Ben
>
>
--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc http://www.candelatech.com
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