Cisco IOS Cookbook, 2nd Edition

Adjusting Local Preference Values

Problem

You want to change the Local Preference values to control which routes you use.

Solution

There are two ways to adjust Local Preference values on a router. The first method changes the Local Preference values for every route distributed into iBGP from this router:

Router1#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)#router bgp 65500
Router1(config-router)#bgp default local-preference 200 
Router1(config-router)#exit
Router1(config)#end
Router1#

The second method uses route maps to give finer granularity control over which routes get what Local Preference values:

Router1#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)#ip prefix-list LOW_LP_PREFIXES seq 10 permit 172.22.0.0/16
Router1(config)#route-map LOCALPREF permit 10
Router1(config-route-map)#match ip address prefix-list LOW_LP_PREFIXES
Router1(config-route-map)#set local-preference 50
Router1(config-route-map)#exit 
Router1(config)#route-map LOCALPREF permit 20
Router1(config-route-map)#exit
Router1(config)#router bgp 65500
Router1(config-router)#neighbor 192.168.1.5 remote-as 65510
Router1(config-router)#neighbor 192.168.1.5 route-map LOCALPREF in
Router1(config-router)#exit
Router1(config)#end
Router1#

Discussion

When BGP routers within an AS exchange information about a particular route using iBGP, they include the Local Preference value. All of the routers in the AS are then able to use this ...