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 modeip as-path access-list as-path-name2. Create a AS-PATH ACL filter with a deny or permit action.AS-PATH ACL mode{deny | permit} as-regular-expression3. Return to CONFIGURATION mode.AS-PATH ACLexit4. 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} filter-list as-path-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.• as-path-name: enter the name of a configured AS-PATH ACL.• in: apply the AS-PATH ACL map to inbound routes.• out: apply the AS-PATH ACL to outbound routes.To view which commands are configured, use the show config command in CONFIGURATIONROUTER BGP mode and the show ip as-path-access-list command in EXEC Privilege mode.To forward all routes not meeting the AS-PATH ACL criteria, include the permit .* filter in your AS-PATHACL.Configuring BGP Route ReflectorsBGP route reflectors are intended for ASs with a large mesh; they reduce the amount of BGP controltraffic.NOTE: Dell Networking recommends not using multipath and add path simultaneously in a routereflector.With route reflection configured properly, IBGP routers are not fully meshed within a cluster but allreceive routing information.Configure clusters of routers where one router is a concentration router and the others are clients whoreceive their updates from the concentration router.To configure a route reflector, use the following commands.212 Border Gateway Protocol IPv4 (BGPv4)
