我们知道不同的vlan之间要相互的通行必须要借用第三层，也就是网络层，可以路由器也可以是三层的交换机。三层拓扑图
图1-6
创建Vlan并设置为服务端
Switch>en
Switch#vlan database
Switch(vlan)#vlan 2 name vlan2
VLAN 2 added:
Name:vlan2
Switch(vlan)#vlan 3 name vlan3
VLAN 3 added:
Name:vlan3
Switch(vlan)#vtp server
Switch(vlan)#vtp domain lcl
VTP domain lcl modified
Switch(vlan)#exit
APPLY completed.
Exiting....
设f0/1为干道
Switch#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)#int f0/1
Switch(config-if)#switchport trunk encapsulation dot1q
Switch(config-if)#switchport mode trunk
Switch(config-if)#end
进入vlan配置ip
Switch#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)#ip routing
Switch(config)#int vlan 2
Switch(config-if)#ip address 192.168.2.1 255.255.255.0
Switch(config-if)#no shut
Switch(config-if)#exit
Switch(config)#int vlan 3
Switch(config-if)#ip address 192.168.3.1 255.255.255.0
Switch(config-if)#no shut
Switch(config-if)#exit
设置为客户端
Switch>en
Switch#vlan database
Switch(vlan)#vtp client
Switch(vlan)#vtp domain lcl
Changing VTP domain from NULL to lcl
Switch(vlan)#exit
APPLY completed.
Exiting....
设f0/1为干道
Switch#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)#int f0/1
Switch(config-if)#switchport trunk encapsulation dot1q
Switch(config-if)#switchport mode trunk
Switch(config-if)#end
端口加入Vlan
Switch#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)#int f0/2
Switch(config-if)#switchport mode access
Switch(config-if)#switchport access vlan 2
Switch(config-if)#exit
Switch(config)#int f0/2
Switch(config-if)#exit
Switch(config)#int f0/3
Switch(config-if)#switchport mode access
Switch(config-if)#switchport access vlan 3
Switch(config-if)#end
结果两个不同vlan的两台PC互ping成功
