[c-nsp] Rationale for ISIS default origination behavior

[Adam Vitkovsky]

Yes I understand what you mean. 
Right the single route is at least some notice that there's something going
on with this peer's BGP table and we better not use it as exit. 
And if all falls apart than you can always use your nearest exist and hope
the doors are not locked if they are thanks to ANYCAST only a local portion
of the net is affected. 

What I meant to say is that "is receiving at least this prefix" and " hoping
the edge works" is all we have right now to make a decision whether to
originate a default route. 
I still lack the BGP table/routing table credibility check before that
particular node originates/advertises a default route. 

adam