实验拓扑：
路由器1：
Router(config)#ip route 0.0.0.0 0.0.0.0 55.0.0.2
动态PAT
Router(config)#access-list 1 permit 192.168.10.0 0.0.0.255
Router(config)#access-list 1 permit 192.168.20.0 0.0.0.255
Router(config)#access-list 1 permit 192.168.200.0 0.0.0.255
Router(config)# ip nat inside source list 1 interface FastEthernet0/1 overload
动态PAT第二种写法
Router(config)#no ip nat inside source list 1 interface FastEthernet0/1 overload
Router(config)# ip nat pool A 55.0.0.5 55.0.0.8 netmask 255.255.255.0
Router(config)#ip nat in
Router(config)#ip nat inside sou
Router(config)#ip nat inside source lis
Router(config)#ip nat inside source list 1 poo
Router(config)#ip nat inside source list 1 pool A ove
Router(config)#ip nat inside source list 1 pool A overload
静态PAT
Router(config)#ip nat inside source static tcp 192.168.100.3 80 55.0.0.9 8888
路由器2：
Router(config)#ip route 57.0.0.0 255.255.255.0 56.0.0.2
路由器3：
Router(config)#ip route 55.0.0.0 255.255.255.0 56.0.0.1
三层交换机：
Switch(config)#ip route 0.0.0.0 0.0.0.0 192.168.1.2
Router(config)#ip route 192.168.10.0 255.255.255.0 192.168.1.1
Router(config)#ip route 192.168.20.0 255.255.255.0 192.168.1.1
Router(config)#ip route 192.168.100.0 255.255.255.0 192.168.1.1