[c-nsp] ISIS and MTU mismatch

[Jason Lixfeld]

> Hello Jason,
> I believe the routed-mtu size on SVI is still 1500 despite system mtu being 1998
> When you change default on 7600 to 9000 you are changing the routed-mtu size.
> ./Randy

I thought about that, but the MTU on the SVI certainly follows the system MTU.  I checked that.  Although it would seem to make sense considering the SVI is technically a routed interface that the MTU should reflect that of the routed MTU, alas.