[c-nsp] Weird problem w/ packet loss on QinQ ports

[Paul Cosgrove]

Hi Garry,

We have seen something similar with 6500s connected using QinQ between 
one ME3400s running metroaccess 12.2(25)SEG3 and one 3750 running ip 
base 12.2(25)SEE2.  Have copied this to my colleague Daniel who is 
working on the issue.  As a matter of interest, are you using UDLD on 
the 4507?

Paul.

Garry wrote:
> One addendum - I've just removed the 4507 from the network, hooking up
> the ME3400's back-to-back ... turns out the packet loss is gone, so it
> must be something with the 4507 -- is there anything additional that
> needs to be configured so that QinQ encapsulated traffic passes through
> correctly?
>
> I activated l2protocol tunneling on the 4507 for testing purposes, that
> also works flawlessly, showing the remote neighbor instead of the 4507
> ...but still, all double-tagged packets cause packet loss ...
>
> Any ideas?
>
> Tnx, -garry
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/
>
>   

Garry wrote:
> Hi,
>
> I'm currently fighting with a weird case of packet loss in a lab
> setup... here goes ...
>
> Setup is as follows, two ME3400 with MetraAccess IOS 12.2.46, are
> connected to a 4507 through GigE ports. Connections are Trunk links.
> VLANs (QinQ, plus other non-QinQ ones) used on the MEs are configured on
> the 4507.
>
> Now, when I hook up two PCs to one of the ME each, using a "switchport
> access" port, both being in the same vlan, everything is fine. Transfer
> rates are fine, no packet loss on floodpings even with large packets (1500).
>
> Now, plugging the PCs into the QinQ ports, which are just configured
> with the basic "switchport access" and "switchport mode dot1q-tunnel", I
> get about 1% packet loss on flood pings with default packet size, with
> increasing loss while increasing packet size. Weird thing is, doing a
> tcpdump on the receiving end, I see the packets arriving, though some
> aren't answered by the PC. I assume they arrive with incorrect checksum
> and therefore are dropped by the stack ...
>
> Anybody have an idea what is going wrong here??? I'm out of ideas ...
>
> Tnx, -garry
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/