[c-nsp] 7200 MPLS MTU Issues

[John Osmon]

On Tue, Mar 15, 2005 at 11:43:11PM -0500, Jon Lewis wrote:
> On Tue, 15 Mar 2005, John Osmon wrote:
> 
> > On Tue, Mar 15, 2005 at 09:44:22PM -0500, Kenny Stoltz wrote:
> > [...]
> > > Ironically, cisco claims that the 7200 can /do/ MPLS... This is almost
> > > laughable if it can't exceed 1500 bytes.
> >
> > If you can find way to migrate the links to GigE and/or serial ports,
> > the routers should work fine.  If you're stuck with ether/fastE, you may
> > need to find another workaround.
> 
> Huh?  The 7200 FEs (both IO/FE and PA-FE) handle the 'oversized' MPLS VPN
> tagged packets just fine.  You have to configure tag-switching and a
> tag-switching MTU on any interface that will be passing tagged packets.
> i.e. Try adding
>  tag-switching mtu 1520
>  tag-switching ip
> to your FE interfaces that need to pass MPLS VPN tagged packets.

mea culpa.  I should engage brain fully before typing.  Some of us get
upset when the 7200 is denegrated -- it's a great beast when used in the
right place.  I wasn't thinking about 'tag-switching mtu' at all.
Thanks for setting things straight.