"unsupported" features in IOS ("mpls mtu") (was: Re: [c-nsp] High Availability PoP Design)

[Gert Doering]

Hi,

On Fri, Nov 04, 2005 at 02:06:07PM -0500, Rodney Dunn wrote:
> On Fri, Nov 04, 2005 at 07:44:41PM +0100, Gert Doering wrote:
> > On Fri, Nov 04, 2005 at 12:31:21PM -0500, Rodney Dunn wrote:
> > > We support 1500 byte ip headers on those PA's +
> > > 6 labels (24) bytes.
> > 
> > So if I understand this correctly, "mpls mtu 1524" will still work on
> > FE ports on 7200?
> 
> Yes.
> 
> > My math is a bit on the weak side today, but is this enough to do 
> > EoMPLS crossconnects?  1500 IP + 14 bytes Ethernet header leaves 
> > 10 Bytes for labels - and you only need 2 labels, so you should be
> > fine... hmmm.
> 
> For the MPLS MTU don't include the ethernet header.
> 
> That's what confused people before.

Indeed, it does.

For "IP over MPLS" (L3 VPN), I understand that I don't need the ethernet
headers, but for "Ethernet over MPLS" (L2 VPN), I don't understand how
it will work without ethernet headers?

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