[c-nsp] Sup 720 dual engine configurations

[matthew zeier]

Voll, Scott wrote:
> Depends on how long you can go without the Router.  If you are using it
> at your core, how long can you be down?  And what kind of SmartNet
> contract do you have.
> 

Well and then if you have multiple core routers, how long can you go 
with with just N?

SSO works well but HA failover on CatOS works really well.

That said, it came down to a cost thing for me at the place I'm at now 
and we're going with single Sups all around.