实现PC0能与PC1、PC2、PC3通信
1.先配置使得vlan内通信，vlan间通信隔离
对switch0
Switch>ena
Switch#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)#vlan 10
Switch(config-vlan)#exit
Switch(config)#vlan 20
Switch(config-vlan)#exit
Switch(config)#int f0/23
Switch(config-if)#switchport mode access
Switch(config-if)#switchport access vlan 20
Switch(config-if)#int f0/24
Switch(config-if)#switchport mode access
Switch(config-if)#switchport access vlan 10
Switch(config-if)#int f0/1
Switch(config-if)#switchport mode trunk
Switch(config-if)#
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up
Switch(config-if)#switchport trunk allowed vlan all
Switch(config-if)#no shutdown
对switch1
Switch>ena
Switch#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)#vlan 10
Switch(config-vlan)#exit
Switch(config)#vlan 20
Switch(config-vlan)#exit
Switch(config-if)#int f0/24
Switch(config-if)#switchport mode access
Switch(config-if)#switchport access vlan 10
Switch(config-if)#int f0/23
Switch(config-if)#switchport mode access
Switch(config-if)#switchport access vlan 20
Switch(config-if)#int f0/1
Switch(config-if)#switchport mode trunk
Switch(config-if)#
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up
Switch(config-if)#switchport trunk allowed vlan all
Switch(config-if)#no shutdown
对三层交换机
Switch>ena
Switch#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)#vlan 10
Switch(config-vlan)#exit
Switch(config)#vlan 20
Switch(config-vlan)#exit
Switch(config)#int f0/1
Switch(config-if)#switchport mode trunk //直接设置trunk口
Command rejected: An interface whose trunk encapsulation is "Auto" can not be configured to "trunk" mode.
Switch(config-if)#switchport trunk allowed vlan all
Switch(config-if)#no shutdown
Switch(config-if)#int f0/2
Switch(config-if)#switchport trunk encapsulation dot1q //以dot1q封装端口
Switch(config-if)#switchport mode trunk //将端口设置为trunk模式
Switch(config-if)#switchport trunk allowed vlan all
Switch(config-if)#no shutdown
Switch(config-if)#end
此时已经配置完成vlan内可以通信，vlan间通信隔离
先设置主机IP
PC0：192.168.10.3 255.255.255.0
PC1：192.168.20.3 255.255.255.0
PC2：192.168.10.2 255.255.255.0
PC3：192.168.20.2 255.255.255.0
2.在三层交换机上配SVI
Switch>ena
Switch#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)#int vlan 10
Switch(config-if)#
%LINK-5-CHANGED: Interface Vlan10, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan10, changed state to up
Switch(config-if)#ip add 192.168.10.1 255.255.255.0
Switch(config-if)#no shutdown
Switch(config-if)#exit
Switch(config)#int vlan 20
Switch(config-if)#
%LINK-5-CHANGED: Interface Vlan20, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan20, changed state to up
Switch(config-if)#ip add 192.168.20.1 255.255.255.0
Switch(config-if)#no shutdown
Switch(config-if)#exit
3.在三层交换机上开启路由功能
Switch(config)#ip routing
4.设置主机网关（相应vlan SVI）
PC0：192.168.10.1
PC1：192.168.20.1
PC2：192.168.10.1
PC3：192.168.20.1
对PC0
已实现vlan间通信