To share what I've learned !

Introduction: This we can use to advertise the prefixes automatically when one peer goes down rather manually advertise the prefixes. Design Notes: In this example I’m trying to advertise 10.0.0.0/16 through AS 65001 but if the peer (203.143.0.5) goes down automatically advertise the 10.0.0.0/16 through AS 65002(203.143.0.1). To make the configuration works we need to match against a prefix that advertise from that(203.143.0.5) peer. But to make sure that learned through that peer we can use AS-Path match or community based match. Here in this example I’m matching against 172.16.0.0/24 advertise through 65001 and match against the as path ^ 65001. Configuration Notes: This is the only configuration different from normal one: neighbor 203.143.0.1 advertise-map otherblock non-exist-map[exist-map] inblock Better notes on this: Normal Status: R2#show ip bgp neighbors 203.143.0.1 | inc Cond Condition-map inblock, Advertise-map otherblock, status: Withdraw R0#show ip route Gateway of last...