Figure 20: Advertising a Default Route When Another Route is Present
The following commands configure router R2:
host1(config)#ip prefix-list default permit 0.0.0.0/0
host1(config)#route-map default permit 10
host1(config-route-map)#match ip address prefix-list default
host1(config-route-map)#exit
host1(config)#ip prefix-list test-default permit 172.55.0.0/16
host1(config)#route-map test permit 10
host1(config-route-map)#match ip address prefix-list test-default
host1(config-route-map)#exit
host1(config)#route-map outbound deny 10
host1(config-route-map)#match ip address prefix-list test-default
host1(config-route-map)#exit
host1(config)#route-map outbound permit 20
host1(config-route-map)#exit
host1(config)#router bgp 200
host1(config-router)#neighbor 10.12.12.2 remote-as 300
host1(config-router)#network 172.55.55.0/24
host1(config-router)#aggregate-address 172.55.0.0/16 summary-only
host1(config-router)#neighbor 10.12.12.2 advertise-map default exist-map test
host1(config-router)#neighbor 10.12.12.2 default-originate
host1(config-router)#neighbor 10.12.12.2 route-map outbound out
host1(config-router)#exit
Configuring BGP Routing Policy
Routing policy determines how the router handles the routes it receives from and
sends to BGP peers or other routing protocols. In many cases, routing policy consists
of filtering routes, accepting certain routes, accepting and modifying other routes,
and rejecting some routes. You can think of routing policy as a way to control the
flow of routes into and out of the router.
You can use one or more of the following mechanisms to configure routing policy:
â– Access lists
â– Community lists
â– Prefix lists
70 â– Configuring BGP Routing Policy
JUNOSe 11.1.x BGP and MPLS Configuration Guide
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