Concept Guide

Filtering BGP Routes Using Route Maps
To lter routes using a route map, use these commands.
1 Create a route map and assign it a name.
CONFIGURATION mode
route-map map-name [permit | deny] [sequence-number]
2 Create multiple route map lters with a match or set action.
CONFIG-ROUTE-MAP mode
{match | set}
For information about conguring route maps, see Access Control Lists (ACLs).
3 Return to CONFIGURATION mode.
CONFIG-ROUTE-MAP mode
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 | ipv6-address | peer-group-name} route-map map-name {in | out}
Congure the following parameters:
• ip-address or ipv6-address or peer-group-name: enter the neighbor’s IPv4 or IPv6 address or the peer group’s name.
• map-name: enter the name of a congured route map.
• in: apply the route map to inbound routes.
• out: apply the route map to outbound routes.
Example conguration of ltering BGP routes using route maps
DellEMC# configure terminal
DellEMC(conf)# route-map route1 permit
DellEMC(conf-route-map)# set as-path prepend 400
DellEMC(conf-route-map)#exit
DellEMC(conf)# router bgp 400
DellEMC(conf-router_bgp)# neighbor 10.10.10.1 route-map route1 out
DellEMC(conf-router_bgp)#
In the above example, a route-map named route1 is created with a permit clause. Within the route-map, a set clause is congured to
prepend an AS is congured. This conguration adds the congured AS number to the AS-Path for each route. The congured route-map
is applied to the outbound routes of the neighbor 10.10.10.1.
To view the BGP conguration, use the show config command in CONFIGURATION ROUTER BGP mode. To view a route map
conguration, use the show route-map command in EXEC Privilege mode.
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Border Gateway Protocol (BGP)