Configuring BGP Peer Groups
XSR User’s Guide 6-27
XSR(config-router)#neighbor 192.168.57.90 send-community
XSR(config-router)#neighbor 192.168.57.90 route-map 111 out
XSR(config-router)#neighbor route-map 111 10 permit
XSR(config-route-map)#match as-path 1
XSR(config-route-map)#set community 50 50 additive
XSR(config-route-map)#route-map 111 20 permit
XSR(config-route-map)#match as-path 2
XSR(config-route-map)#ip as-path access-list 1 permit 7$
XSR(config-route-map)#ip as-path access-list 2 permit .*
Thirdly, community-based matching selectively sets MED and local-preference values for
neighbor 192.168.57.55’s routes. All the routes that match community list 1 get a MED of 60
including any with communities 10 20 30 or 90 91. These routes may have other community
parameters too.
A local preference of 30 is set for all routes that pass community list 2 including those with
community values 8 or 9. If the routes belong to any other community, no matching by
community list 2 is done.
A local preference of 40 is set for all routes matching community list 3 which matches all the
routes because they are members of the Internet community. So, the remainder of neighbor
192.168.57.55’s routes get local preference 40.
XSR(config)#router bgp 20
XSR(config-router)#neighbor 192.168.57.55 remote-as 10
XSR(config-router)#neighbor 192.168.57.55 route-map 101 in
XSR(config-router)#route-map 101 10 permit
XSR(config-route-map)#match community-list 1
XSR(config-route-map)#set metric 60
XSR(config-route-map)#route-map 101 20 permit
XSR(config-route-map)#match community-list 2
XSR(config-route-map)#set local-preference 30
XSR(config-route-map)#route-map 101 30 permit
XSR(config-route-map)#match community-list 3
XSR(config-route-map)#set local-preference 40
XSR(config-route-map)#exit
XSR(config)#ip community-list 1 permit 10 20 30
XSR(config)#ip community-list 1 permit 90 91
XSR(config)#ip community-list 2 permit 8
XSR(config)#ip community-list 2 permit 9
XSR(config)#ip community-list 3 permit internet
Route map 55 is applied to the outgoing updates for neighbor 192.168.57.50 in this example.
Routes that pass ACL 1 have the special community attribute value local-as, with other routes
advertised as usual. Local-as automatically prevents BGP speakers outside AS 20 from advertising
those routes.
XSR(config)#router bgp 23
XSR(config-router)#network 1.0.0.0 mask 255.0.0.0