[c-nsp] 6500/7600 with Sup720 opinion

[Neil J. McRae]

7609 can be uses as PE, P and PE-Agg its one of the stronger
boxes for MPLS, but its also the worst for really bad IOS Code.
The port density for the 7609 is very good and getting better 
with future roadmap items.

> I thought the 7600 MPLS functionality was severely limited - 
> could only act as a core, not edge device or similar? (I 
> forget the details)
> 
> (We're deploying 7600s next month, MPLS won't be needed 
> immediately but we'll need it in around 6 months time - was 
> planning to use 7200s at the
> edge)