[c-nsp] BGP partial routes and partial carrier failures

[Paul Wozney]

> You could, for instance, use Conditional
> Advertisements to inject the default based on the presence or absence of
> routing information from one or the other provider.

I like this a lot!  I could use conditional advertisements to control
when prefixes are advertised, and condition route injection to control
the insertion of a default route.

> Taking full routes achieves the same thing (by getting
> rid of default), but you can solve this issue without the additional memory
> load and potentially cost.

We're running ASR-1002-F so we're right up against the wall on the
full routes question.