一、拓撲圖:
二、配置各路由器的IP位址,并運作BGP協定。
1、為了讓R3學到明細路由,我們把R1自動彙總關掉:
R1(config)#router bgp 64512
R1(config-router)#no auto-summary
R1(config-router)#net 172.16.255.0 mask 255.255.255.252
R1(config-router)#net 172.16.0.1 mask 255.255.255.252
R1(config-router)#net 172.16.0.0 mask 255.255.255.0
R1(config-router)#net 172.16.1.0 mask 255.255.255.0
R1(config-router)#net 172.16.2.0 mask 255.255.255.0
R1(config-router)#net 172.16.3.0 mask 255.255.255.0
R1(config-router)#nei 172.16.255.2 remote 64512
R2(config-if)#router bgp 64512
R2(config-router)#net 172.16.255.0 mask 255.255.255.252
R2(config-router)#net 10.1.255.0 mask 255.255.255.252
R2(config-router)#nei 172.16.255.1 remote 64512
R2(config-router)#nei 10.1.255.2 remote 64513
R3(config-if)#router bgp 64513
R3(config-router)#net 10.1.255.0 mask 255.255.255.252
R3(config-router)#nei 10.1.255.1 remote 64512
2、配置完之後,看一下R3的路由表:
R3#sh ip route
…………
Gateway of last resort is not set
172.16.0.0/16 is variably subnetted, 5 subnets, 2 masks
B 172.16.255.0/30 [20/0] via 10.1.255.1, 00:08:58
B 172.16.0.0/24 [20/0] via 10.1.255.1, 00:08:58
B 172.16.1.0/24 [20/0] via 10.1.255.1, 00:08:58
B 172.16.2.0/24 [20/0] via 10.1.255.1, 00:08:58
B 172.16.3.0/24 [20/0] via 10.1.255.1, 00:08:58
10.0.0.0/30 is subnetted, 1 subnets
C 10.1.255.0 is directly connected, Serial1/0
三、在R2上建立ACL,并用分發清單去應用ACL以達到過濾指定的路由:
R2(config)#access-list 1 deny 172.16.0.0 0.0.0.255
R2(config)#access-list 1 deny 172.16.1.0 0.0.0.255
R2(config)#access-list 1 per any (其它路由都不拒絕)
R2(config-router)#nei 10.1.255.2 distribute-list 1 out (對目标鄰居應用分發清單)
四、再來檢視一下R3的路由表,發現指定的兩條路由被過濾掉了:
R3#clear ip bgp * soft (軟涮新一下BGP資料庫)
………………
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
B 172.16.255.0/30 [20/0] via 10.1.255.1, 00:17:19
B 172.16.2.0/24 [20/0] via 10.1.255.1, 00:17:19
B 172.16.3.0/24 [20/0] via 10.1.255.1, 00:17:19
R3#
本文轉自wxs-163 51CTO部落格,原文連結:http://blog.51cto.com/supercisco/273886