Other ISPs who happen to be in position to control physical
routing of circuits use IP-level rerouting to attack the problem.The IGP rerouting with modern link-state IGPs is sub-second
so the redundancy of interior paths is easy to achieve (perticularly
if you use tricks like BGP confederations which eliminate
need to recompute iBGP routing in case of IGP changes).
Vadim,
Can you be more specific about this? How do you avoid
the recompute and also avoid persistent routing loops after a
topology change?
The hard part is exterior routing where topology changes require
massive crunching of BGP tables. Multiplying paths actually
makes the problem worse.
You bet!
Erik