Figure 21: Filtering With Access Lists; Figure 22: Filtering Routes With An Access List - Juniper BGP - CONFIGURATION GUIDE V 11.1.X Configuration Manual

JUNOSe 11.1.x BGP and MPLS Configuration Guide

Figure 21: Filtering with Access Lists

The following commands configure router Boston to apply access list reject1 to routes
inbound from router SanJose. Access list reject1 rejects routes matching
172.24.160.0/19.
Consider the network shown in Figure 22 on page 84. Router NY originates network
10.16.22.0/23 and advertises it to router LA. Suppose you do not want router LA to
advertise that network to router Boston. You can apply an access list to updates from
router LA to router Boston that prevents router LA from propagating updates for
network 10.16.22.0/23.

Figure 22: Filtering Routes with an Access List

The following commands configure router LA:
84
Configuring BGP Routing Policy
host3(config)#router bgp 17
host3(config-router)#neighbor 10.5.5.4 remote-as 873
host3(config-router)#neighbor 10.5.5.4 distribute-list reject1 in
host3(config-router)#exit
host3(config)#access-list reject1 permit 172.24.48.0 0.0.255
host3(config)#access-list reject1 deny 172.24.160.0 0.0.255
host3(config)#access-list reject1 permit 172.24.24.0 0.0.255
host2(config)#router bgp 400
host2(config-router)#network 172.24.160.0 mask 255.255.224.0
host2(config-router)#neighbor 10.72.4.2 remote-as 300
host2(config-router)#neighbor 10.5.5.1 remote-as 100
host2(config-router)#neighbor 10.5.5.1 distribute-list 1 out