BGP route-map checking

[mstubbers]

Is there a method to perform the inverse of the route-map then advertise command in BGP? I have two links to an ISP A, One link to ISP B. I want to use one link to ISP A until my link to ISP B fails, then use the other. I can use the route-map to detect the ISP B failure and begin announcing to ISP A, but in the mean time I would like to have local traffic between us and ISP A use the second path until the failure of ISP B.

If I haven't confused you enough, I believe what I'm looking for is the ability to watch a network in my routing table from ISP B. When it goes away, then STOP advertising to ISP A.

[noc]

Give us more information - are your two links to ISP A the same speed, to they go to the same router. If i was you I would get them to, so you can run

Maximum-paths 2 with that peer, or even better

MLPPP and mux them into one logical link to the BGP process.

You can use the command

"neighbor X.X.X.X allowas-in"

to accept prefixs containing, you AS, then you can match these routes (referring to an ACL) in your

route-map then if the condition is met, perform some

actions which may be what you looking for.

But once again, unless you have some wierd sized differencial links to ISP A (like a 256Kbps frame

and a DS-3) I would definately run MLPPP and mux the two links. It will make your routers bgp process easier and the CPU is does consume, will be negligable compared to the second another bgp session to the same AS.