[e2e] fast restoration/protection

[Amund Kvalbein]

Craig,

>
> As for the first -- do we know or have we thought of ways to determine
> which FIBs it would be useful to have?  I.e., don't solve all possible
> failures -- pick the best subset of FIBS given a limit on the number of
> FIBS (say 5) and current statistics on link outages.  There's also a clear
> metric for goodness -- namely, take the list of outages, weighted by
> their likelihood, and see what fraction of [weighted] outages are covered
> by the set of alternate FIBS.  Obviously a metric of 1.0 is desired, but
> I'll bet any metric over, say, 0.6 has an impact.
>

We have done some work on this. It turns out that you can actually 
construct a very limited number of topologies/FIBs that cover all possible 
failures. We typically need five or less for existing networks.  This is 
done by carefully selecting a subset of routers that are not used to 
forward packets in each topology.

See http://www.simula.no/departments/networks/.artifacts/infocom06 for 
details.

Regards,
Amund