[c-nsp] Problems with dot1q trunk over EoMPLS with WS-X6148-GE-TX

[Gert Doering]

Hi,

On Sun, Aug 08, 2010 at 01:39:16PM +0200, Marco Matarazzo wrote:
> >... just put "mtu 1504" here, to take into account that a full-sized
> >ethernet frame *plus* dot1q header is just bigger than without... :-)
> >
> >(Been there, cursed, found the answer)
> 
> I tried doing that (actually tried to bump to 1546, but I don't think it
> makes any difference) but the VC went down as soon as I did it. That's
> because for the VC to work the mtu must be the same on both endpoint ports

Yes, this is the expected behaviour - it needs to be changed on both sides.

> and there is no mtu command available on those 6148 non A cards at the other
> end of the link... do you think it would make any difference with 1504?

I didn't fully read your posting, sorry for that - you need to bump the
mtu on both sides, and if the card can't do that, this easy solution won't
work for you.

What you can do, if you know "the customer only has 5 VLANs and this
won't change in the foreseeable future" is to configure one EoMPLS bridge
per VLAN, on "FastEthernet2/32.123 / encaps dot1q 123".

This is not possible, of course, if you don't know which VLAN tags your
customer uses, have used the same tages elsewhere on the 6500, or there
are so many active VLANs that you end up adding subinterfaces for the
next week...

gert
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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de