September 20, 2009

Filter networks with BGP

There are 3 easy ways to filter/restrict certain networks to be announced through BGP to a remote/adjacent AS (Autonomous System). Those 3 simple ways include: prefix-list | Extended Access-list + Route-map | Extended Access-list + Distribute-list To Note: before we go on, I need to specify that creating an extended access list to be in use with BGP (route-map, distribute-list) is almost as similar as creating a prefix-list… Having said that, we are therefore no longer matching source and destination address but merely address prefix and netmask with the access list. ... Read more