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

[Saku Ytti]

On (2005-11-04 19:44 +0100), Gert Doering wrote:
> hi,
> 
> 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?
> 
> 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.

 Is it enought? Don't you need 1526?

 2xlabels 8bytes, ethernet vlan mode 18bytes, 1500 payload = 1526
you could also possibly need FRR +4bytes? Or if you're using atm over mpls
you'd need lot more.

> gert
> 
> -- 
> USENET is *not* the non-clickable part of WWW!
>                                                            //www.muc.de/~gert/
> Gert Doering - Munich, Germany                             gert at greenie.muc.de
> fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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-- 
  ++ytti