Figure 26: Communities - Juniper BGP - CONFIGURATION GUIDE V 11.1.X Configuration Manual

Use the set community command in route maps to configure the community
attributes. By default, the community attribute is not sent to BGP peers. To send the
community attribute to a neighbor, use the neighbor send-community command.
Consider the network structure shown in Figure 26 on page 93. The following sample
configurations illustrate some of the capabilities of using the community attribute.

Figure 26: Communities

The following commands configure router NY to apply route map setcomm to routes
going out to 10.72.4.3. If the community attribute of such a route matches instance
10 of the route map, router NY sets the community attribute to 31:15. All locally
originated routes will match this instance of the route map.
The following commands configure router LA to apply route map matchcomm to
routes coming in from 10.72.4.2. If the community attribute of such a route matches
instance 10 of the route map, router LA sets the weight of the route to 25.
host1(config)#router bgp 31
host1(config-router)#network 10.16.22.0 mask 255.255.254.0
host1(config-router)#neighbor 10.72.4.3 remote-as 425
host1(config-router)#neighbor 10.72.4.3 send-community
host1(config-router)#neighbor 10.72.4.3 route-map setcomm out
host1(config-router)#exit
host1(config)#ip as-path access-list 1 permit ^$
host1(config)#route-map setcomm permit 10
host1(config-route-map)#match as-path 1
host1(config-route-map)#set community 31:15
host2(config)#router bgp 425
host2(config-router)#network 172.24.160 mask 255.255.224.0
host2(config-router)#neighbor 10.72.4.2 remote-as 31
host2(config-router)#neighbor 10.72.4.2 send-community
host2(config-router)#neighbor 10.72.4.2 route-map matchcomm in
host2(config-router)#neighbor 10.5.5.1 remote-as 122
host2(config-router)#neighbor 10.5.5.1 send-community
host2(config-router)#exit
host2(config)#ip community-list 1 permit 31:15
host2(config)#route-map matchcomm permit 10
host2(config-route-map)#match community 1
host2(config-route-map)#set weight 25
Chapter 1: Configuring BGP Routing
Configuring BGP Routing Policy
93