A good Internet service provider will also be looking at SNMP counters
and other indications of trouble on a regular basis using automated
tools and should be able to detect a problem independent of routing.
If your links are very noisy, routing will usually stay up anyway and
a very high percentage of packets may go in the bit bucket. Worse yet
is when routing can't decide whether to use the link or not and
changes its decision every few minutes. Too many shoddy providers are
not looking at link conditions and relying on routing to go down.
Multiply that by a few hundred flakey circuits around the world at any
given time and you have the current load on today's backbone routers.
Since the backbones can't fix the source of the problem, it becomes
nessecary to make the protocol machinery able to deal with the problem
somehow. That's were the route flap dampenning work comes in.
Curtis