PC1 ip 192.168.1.1
PC2  ip  192.168.4.1
路由0  f0/0 192.168.1.254
              f0/1 192.168.2.1
路由1  f0/0 192.168.3.1
              f0/1 192.168.2.2
路由2  f0/0 192.168.4.254
              f0/1 192.168.3.2
路由器0
Router>en
Router#conf t
Router(config)#no ip domain-lookup
Router(config)#line console 0
Router(config-line)#logging synchronous
Router(config-line)#password aaa
Router(config-line)#login
Router(config-line)#exit
Router(config)#enable secret aaa
Router(config)#login
Router(config)#int f0/0
Router(config-if)#ip add 192.168.1.254 255.255.255.0
Router(config-if)#no shut
Router(config-if)#int f0/1
Router(config-if)#ip add 192.168.2.1 255.255.255.0
Router(config-if)#no shut
Router(config-if)#exit
Router(config)#exit
Router#wr
Router#showip route
C192.168.1.0/24 is directly connected, FastEthernet0/0
C192.168.2.0/24 is directly connected, FastEthernet0/1
Router#conf t
Router(config)#ip route 192.168.3.0 255.255.255.0 192.168.2.2
Router(config)#ip route 192.168.4.0 255.255.255.0 192.168.3.2
Router(config)#exit
Router#wr
Router#showip route
C192.168.1.0/24 is directly connected, FastEthernet0/0
C192.168.2.0/24 is directly connected, FastEthernet0/1
S192.168.3.0/24 [1/0] via 192.168.2.2
S192.168.4.0/24 [1/0] via 192.168.3.2
路由器1
Router>en
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#no ip domain-lookup
Router(config)#line console 0
Router(config-line)#loggsy
Router(config-line)#password aaa
Router(config-line)#login
Router(config-line)#exit
Router(config)#enable secret aaa
Router(config)#login
Router(config)#int f0/0
Router(config-if)#ip add 192.168.3.1 255.255.255.0
Router(config-if)#no shut
Router(config-if)#int f0/1
Router(config-if)#no shut
Router(config-if)#ip add 192.168.2.2 255.255.255.0
Router(config-if)#no shut
Router(config-if)#exit
Router(config)#exit
Router#wr
Router#showip route
C192.168.2.0/24 is directly connected, FastEthernet0/1
C192.168.3.0/24 is directly connected, FastEthernet0/0
Router#conf t
Router(config)#ip route 192.168.1.0 255.255.255.0 192.168.2.1
Router(config)#ip route 192.168.4.0 255.255.255.0 192.168.3.2
Router(config)#exit
Router#wr
Router#showip route
S192.168.1.0/24 [1/0] via 192.168.2.1
C192.168.2.0/24 is directly connected, FastEthernet0/1
C192.168.3.0/24 is directly connected, FastEthernet0/0
S192.168.4.0/24 [1/0] via 192.168.3.2
路由2
Router>en
Router#conf t
Router(config)#no ip domain-lookup
Router(config)#line console 0
Router(config-line)#loggsy
Router(config-line)#password aaa
Router(config-line)#login
Router(config-line)#exit
Router(config)#enable secret aaa
Router(config)#login
Router(config)#int f0/0
Router(config-if)#ip add 192.168.4.254 255.255.255.0
Router(config-if)#no shut
Router(config-if)#int f0/1
Router(config-if)#ip add 192.168.3.2 255.255.255.0
Router(config-if)#no shut
Router(config-if)#exit
Router(config)#exit
Router#wr
Router#showip route
C192.168.3.0/24 is directly connected, FastEthernet0/1
C192.168.4.0/24 is directly connected, FastEthernet0/0
Router#conf t
Router(config)#ip route 192.168.2.0 255.255.255.0 192.168.3.1
Router(config)#ip route 192.168.1.0 255.255.255.0 192.168.2.1
Router(config)#exit
Router#wr
Router#showip route
S192.168.1.0/24 [1/0] via 192.168.2.1
S192.168.2.0/24 [1/0] via 192.168.3.1
C192.168.3.0/24 is directly connected, FastEthernet0/1
C192.168.4.0/24 is directly connected, FastEthernet0/0