[c-nsp] Route-Map Question/Advice

Pete Templin petelists at templin.org
Thu Feb 16 21:50:10 EST 2006

Joe Maimon wrote:
> A set of maintenance route-maps, hmmm interesting.

Yep, I don't leave home without them.  Many reasons:

1: Back in the days of having two transits, turning one off to do 
maintenance means a problem on the other is catastrophic. 
Depreferencing both ways on one means I can abort the maintenance and at 
least have the ability to get back in.

2: I've had 'issues' where switching to a no-routes route map and 
soft-out-clearing the session hasn't actually stopped my announcements. 
  Switching to depreferenced announcements and then no-routes worked 
better, or at least lessened the impact dramatically if the session dropped.

3: Leaving some form of direct route in the provider's routers seems to 
result in much cleaner forwarding transitions, and often less dampening 
on other paths.

4: Obviously, taking traffic off a link before bouncing the link means 
the bit bucket sees fewer packets.  OSPF's max-metric router-lsa works 
great on internal nodes that can be avoided, etc.

5: Since many folks do uRPF, I make sure to tweak the inbound route map 
and converge my outbound traffic elsewhere before tweaking the outbound 
route map and converging my inbound traffic elsewhere, so that my 
outbound traffic doesn't die in provider's uRPF filters.  Restoring 
traffic onto the link is done in the reverse, obviously.


More information about the cisco-nsp mailing list