Cisco IOS Cookbook 中文精简版第九章 BGP

9.4. 连接两个ISPs

提问 一台路由器连接两个ISP，保证网络冗余

回答

Router1#configure terminal

Enter configuration commands, one per line. End with CNTL/Z.

Router1(config)#interface Serial0

Router1(config-if)#description connection to ISP #1, ASN 65510

Router1(config-if)#ip address 192.168.1.6 255.255.255.252

Router1(config-if)#exit

Router1(config)#interface Serial1

Router1(config-if)#description connection to ISP #2, ASN 65520

Router1(config-if)#ip address 192.168.2.6 255.255.255.252

Router1(config-if)#exit

Router1(config)#interface Ethernet0

Router1(config-if)#description connection to internal network, ASN 65500

Router1(config-if)#ip address 172.18.5.2 255.255.255.0

Router1(config-if)#exit

Router1(config)#router bgp 65500

Router1(config-router)#network 172.18.5.0 mask 255.255.255.0

Router1(config-router)#neighbor 192.168.1.5 remote-as 65510

Router1(config-router)#neighbor 192.168.2.5 remote-as 65520

Router1(config-router)#no synchronization

Router1(config-router)#exit

Router1(config)#end

Router1#

注释 注意此配置不是最佳配置，可能导致内部AS称为两个ISP的transit AS，同时导致自己路由器接收过多路由

9.5. 两台路由器分别连接两个ISP

提问 内部AS有两台路由器，分别连两个ISP保证网络冗余

回答

Router1#configure terminal

Enter configuration commands, one per line. End with CNTL/Z.

Router1(config)#interface Serial0

Router1(config-if)#description connection to ISP #1, ASN 65510

Router1(config-if)#ip address 192.168.1.6 255.255.255.252

Router1(config-if)#exit

Router1(config)#interface Ethernet0

Router1(config-if)#description connection to internal network, ASN 65500

Router1(config-if)#ip address 172.18.5.2 255.255.255.0

Router1(config-if)#exit