1.按照試驗拓撲,配置好路由器的各個接口IP；
2.使用ping命令驗證路由器之間的連同性，以r1爲例：
r1#ping 10.3.3.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.3.3.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 40/67/116 ms
略......
再用r1 ping r2的loopback和r3的ip：
r1#ping 192.168.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
略......
r1無法ping通r2的loopback地址和r3的ip地址，需要添加靜態路由。
3.下面在3臺路由器上使用命令ip route添加相應的靜態路由：
r1(config)#ip route 192.168.1.0 255.255.255.0 10.3.3.2 //設置靜態路由到192.168.1.0/24， 下一跳地址爲10.3.3.2 r1(config)#ip route 172.16.3.0 255.255.255.0 10.3.3.2
r1(config)#ip route 172.16.1.0 255.255.255.0 10.3.3.2
r1(config)#ip route 172.16.2.0 255.255.255.224 10.3.3.2
r2(config)#ip route 10.1.1.0 255.255.255.0 10.3.3.1
r2(config)#ip route 10.2.2.0 255.255.255.224 10.3.3.1
r2(config)#ip route 172.16.1.0 255.255.255.0 172.16.3.1
r2(config)#ip route 172.16.2.0 255.255.255.224 172.16.3.1
r3(config)#ip route 192.168.1.0 255.255.255.0 172.16.3.2
r3(config)#ip route 10.3.3.0 255.255.255.0 172.16.3.2
r3(config)#ip route 10.1.1.0 255.255.255.0 172.16.3.2
r3(config)#ip route 10.2.2.0 255.255.255.224 172.16.3.2
然後再次驗證：
r1#ping 192.168.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 56/59/60 ms
其餘略......
可以ping通。
查看一下r1的路由表：
r1#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
S 172.16.1.0/24 [1/0] via 10.3.3.2
S 172.16.2.0/27 [1/0] via 10.3.3.2
S 172.16.3.0/24 [1/0] via 10.3.3.2
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
C 10.3.3.0/24 is directly connected, Serial1/1
C 10.2.2.0/27 is directly connected, Loopback1
C 10.1.1.0/24 is directly connected, Loopback0
S 192.168.1.0/24 [1/0] via 10.3.3.2
S代表靜態路由。（其餘路由器略......）
總結：其實如果路由器屬於末梢節點的話，可以只用一條默認路由也可以實現上面的效果，例如r1：
r1(config)#ip route 0.0.0.0 0.0.0.0 10.3.3.2
這樣也可以ping通其餘的ip地址。