Users Guide

deny 32$
Dell#
Filtering BGP Routes Using AS-PATH Information
To lter routes based on AS-PATH information, use these commands.
1. Create an AS-PATH ACL and assign it a name.
CONFIGURATION mode
ip as-path access-list as-path-name
2. Create an AS-PATH ACL lter with a deny or permit action.
AS-PATH ACL mode
{deny | permit} as-regular-expression
3. Return to CONFIGURATION mode.
AS-PATH ACL
exit
4. Enter ROUTER BGP mode.
CONFIGURATION mode
router bgp as-number
5. Filter routes based on the criteria in the congured route map.
CONFIG-ROUTER-BGP mode
neighbor {ip-address | peer-group-name} filter-list as-path-name {in | out}
Congure 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 congured 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 congured, use the show config command in CONFIGURATION ROUTER 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 .* lter in your AS-PATH ACL.
Redistributing Routes
In addition to ltering routes, you can add routes from other routing instances or protocols to the BGP process. With the
redistribute command, you can include ISIS, OSPF, static, or directly connected routes in the BGP process.
To add routes from other routing instances or protocols, use any of the following commands in ROUTER BGP mode.
• Include, directly connected or user-congured (static) routes in BGP.
ROUTER BGP or CONF-ROUTER_BGPv6_ AF mode
redistribute {connected | static} [route-map map-name]
Congure the map-name parameter to specify the name of a congured route map.
• Include specic ISIS routes in BGP.
ROUTER BGP or CONF-ROUTER_BGPv6_ AF mode
redistribute isis [level-1 | level-1-2 | level-2] [metric value] [route-map map-name]
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Border Gateway Protocol IPv4 (BGPv4)