在GNS3做单臂路由实验
如图所示：
用路由器模拟PC，R2模拟PC1，R3模拟PC2，R4模拟PC3。配置如下：
PC1：
R2#conf t
R2(config)#int f0/0
R2(config-if)#ip add
R2(config-if)#ip address 192.168.1.1 255.255.255.0
R2(config-if)#no sh
R2(config-if)#exit
R2(config)#ip default-gateway 192.168.1.254 （配置PC网关）
R2(config)#no ip routing
R2(config)#end
R2#
PC2：
R3#conf t
R3(config)#int f0/0
R3(config-if)#ip address 192.168.2.1 255.255.255.0
R3(config-if)#no sh
R3(config-if)#exit
R3(config)#no ip routing
R3(config)#ip default-gateway 192.168.2.254（配置PC网关）
R3(config)#end
R3#
PC3：
R4#
R4#conf t
R4(config)#int f0/0
R4(config-if)#ip address 192.168.3.1 255.255.255.0
R4(config-if)#no sh
R4(config-if)#exit
R4(config)#
R4(config)#no ip routing
R4(config)#ip default-gateway 192.168.3.254（配置PC网关）
R4(config)#end
R4#
ESW1：
ESW1#
ESW1#vlan database
ESW1(vlan)#vlan 10 name vlan10
VLAN 10 added:
Name: vlan10
ESW1(vlan)#vlan 20 name vlan20
VLAN 20 added:
Name: vlan20
ESW1(vlan)#vlan 30 name vlan30
VLAN 30 added:
Name: vlan30
ESW1(vlan)#exit
APPLY completed.
Exiting....
ESW1#conf t
ESW1(config)#int f1/0
ESW1(config-if)#switchport mode access
ESW1(config-if)#switchport access vlan 10（把端口加入vlan 10）
ESW1(config-if)#no sh
ESW1(config-if)#exit
ESW1(config)#int f1/1
ESW1(config-if)#switchport mode access
ESW1(config-if)#switchport access vlan 20（把端口加入vlan 20）
ESW1(config-if)#no shutdown
ESW1(config-if)#exit
ESW1(config)#interface f1/2
ESW1(config-if)#switchport mode access
ESW1(config-if)#switchport access vlan 30（把端口加入vlan 30）
ESW1(config-if)#no shutdown
ESW1(config-if)#exit
ESW1(config)#int f1/3
ESW1(config-if)#no sh
ESW1(config-if)#switchport mode trunk
ESW1(config-if)#switchport trunk encapsulation dot1q（二层端口封装802.1q协议（dot1q），也就是trunk链路的中继协议）
ESW1(config-if)#end
ESW1#
R1：
R1#conf t
R1(config)#int f0/0
R1(config-if)#no shutdown
R1(config-if)#exit
R1(config)#int f0/0.1（进入子端口）
R1(config-subif)#ip address 192.168.1.254 255.255.255.0
R1(config-subif)#no sh
R1(config-subif)#encapsulation dot1Q 10（路由器配置了dot1q中继封装，10是vlan 10）
R1(config-subif)#exit
R1(config)#int f0/0.2（进入子端口）
R1(config-subif)#ip address 192.168.2.254 255.255.255.0
R1(config-subif)#encapsulation dot1Q 20（路由器配置了dot1q中继封装，20是vlan 20）
R1(config-subif)#no sh
R1(config-subif)#exit
R1(config)#int f0/0.3（进入子端口）
R1(config-subif)#ip address 192.168.3.254 255.255.255.0
R1(config-subif)#encapsulation dot1Q 30（路由器配置了dot1q中继封装，30是vlan 30）
R1(config-subif)#no shutdown
R1(config-subif)#exit
R1(config)#end
R1#
验证一下：
R2#ping 192.168.1.254（ping 网关）
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.254, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/12/24 ms
R2#ping 192.168.2.1（ping PC2）
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.2.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 16/20/28 ms
R2#ping 192.168.3.1（ping PC3）
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.3.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 16/20/28 ms
R2#
R3#ping 192.168.2.254（ping 网关）
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.2.254, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/11/24 ms
R3#ping 192.168.1.1（ping PC1）
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 = 16/24/32 ms
R3#ping 192.168.3.1（ping PC3）
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.3.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 12/22/32 ms
R3#
R4#ping 192.168.3.254（ping 网关）
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.3.254, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/12/32 ms
R4#ping 192.168.1.1 （ping PC1）
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 = 16/22/40 ms
R4#ping 192.168.2.1（ping PC2）
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.2.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 12/20/36 ms
R4#
来源：51CTO
作者：奋斗者励志
链接：https://blog.51cto.com/chentongsan/2459591