• If none of the routes match any of the filters in the prefix list, the route is denied. This action is called an implicit deny. (If you want toforward all routes that do not match the prefix list criteria, you must configure a prefix list filter to permit all routes. For example, youcould have the following filter as the last filter in your prefix list permit 0.0.0.0/0 le 32).• After a route matches a filter, the filter’s action is applied. No additional filters are applied to the route.To view the BGP configuration, use the show config command in ROUTER BGP mode. To view a prefix list configuration, use the showip prefix-list detail or show ip prefix-list summary commands in EXEC Privilege mode.Filtering BGP Routes Using Route MapsTo filter routes using a route map, use these commands.1 Create a route map and assign it a name.CONFIGURATION moderoute-map map-name [permit | deny] [sequence-number]2 Create multiple route map filters with a match or set action.CONFIG-ROUTE-MAP mode{match | set}For information about configuring route maps, see Access Control Lists (ACLs).3 Return to CONFIGURATION mode.CONFIG-ROUTE-MAP modeexit4 Enter ROUTER BGP mode.CONFIGURATION moderouter bgp as-number5 Filter routes based on the criteria in the configured route map.CONFIG-ROUTER-BGP modeneighbor {ip-address | peer-group-name} route-map map-name {in | out}Configure the following parameters:• ip-address or peer-group-name: enter the neighbor’s IP address or the peer group’s name.• map-name: enter the name of a configured route map.• in: apply the route map to inbound routes.• out: apply the route map to outbound routes.To view the BGP configuration, use the show config command in CONFIGURATION ROUTER BGP mode. To view a route mapconfiguration, use the show route-map command in EXEC Privilege mode.Filtering BGP Routes Using AS-PATH InformationTo filter routes based on AS-PATH information, use these commands.1 Create a AS-PATH ACL and assign it a name.CONFIGURATION mode216 Border Gateway Protocol IPv4 (BGPv4)
