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

[Rodney Dunn]

We support 1500 byte ip headers on those PA's +
6 labels (24) bytes.

That is minus the ethernet/dot1	headers.

The problem was we originally didn't do per bounds checking
on each filed (it's too performance impacting).

It's an extremely complicated set of things on how and
when fragmentation is done.

People thought the tag mtu command was doing something it wasn't
in the first place so that's why we changed it.

Rodney

On Thu, Nov 03, 2005 at 07:19:57PM +0100, Johannes Resch wrote:
> On Thu, November 3, 2005 15:33, Saku Ytti said:
> >
> >  Also as of 12.2(25)S you can't have bridge-group and MPLS in same
> > physical interface under different logical interface. In older IOS' it's
> > no
> > problem and it works. There is (was) no documentation that support has
> > been
> > removed in release notes. Rationale is, that it was never supposed to be
> > working.
> >  Kind of reminds me when VPND was removed between 12.2(14)S3 and S5 or so,
> > without hint (as it shouldn't have been there any way, but worked).
> 
> since you mentioned some cases of sudden disappearance of features without
> notification and between minor releases of a IOS train:
> 
> another example is the upcoming removal of support for "mpls mtu <x>" for
> x being larger than 1500 byte on PA-FE (which did work just fine so far)
> in the 12.2S train (confirmed at least on c7200) - great fun!
> 
> ciscos rationale is (you may have guessed it) that it was never officially
> supported / supposed to be working in the first place.
> 
> if this particular upcoming change is a problem for anybody else than us,
> please drop me a mail off-list - maybe we can bundle efforts.
> 
> regards,
> -jr
> 
> 
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