三层交换机配置：
Switch>enable
Switch#configure terminal
Switch(config)#vlan 10
Switch(config-vlan)#vlan 20
Switch(config-vlan)#vlan 30
Switch(config-vlan)#vlan 40
Switch(config-vlan)#exit
Switch(config)#int vlan 10
Switch(config-if)#ip add 192.168.10.254 255.255.255.0
Switch(config-if)#no shutdown
Switch(config-if)#int vlan 20
Switch(config-if)#ip add 192.168.20.254 255.255.255.0
Switch(config-if)#no shutdown
Switch(config-if)#int vlan 30
Switch(config-if)#ip add 192.168.30.254 255.255.255.0
Switch(config-if)#no shutdown
Switch(config-if)#int vlan 40
Switch(config-if)#ip add 192.168.40.254 255.255.255.0
Switch(config-if)#no shutdown
Switch(config)#int range g1/0/1-2
Switch(config-if-range)#switchport trunk encapsulation dot1q
Switch(config-if-range)#switchport mode trunk
Switch(config-if-range)#switchport trunk allowed vlan all
Switch(config)# ip routing //开启路由功能
Switch(config)#do show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
C 192.168.10.0/24 is directly connected, Vlan10
C 192.168.20.0/24 is directly connected, Vlan20
C 192.168.30.0/24 is directly connected, Vlan30
C 192.168.40.0/24 is directly connected, Vlan40
交换机sw1的配置：
Switch>enable
Switch#conf terminal
Switch(config)#vlan 10
Switch(config-vlan)#vlan 20
Switch(config-vlan)#int g0/1
Switch(config-if)#switchport mode trunk
Switch(config-if)#switchport trunk allowed vlan all
Switch(config-if)#int f0/1
Switch(config-if)#switchport mode access
Switch(config-if)#switchport access vlan 10
Switch(config-if)#int f0/2
Switch(config-if)#switchport mode access
Switch(config-if)#switchport access vlan 20
交换机sw2的配置：
Switch>enable
Switch#conf terminal
Switch(config)#vlan 30
Switch(config-vlan)#vlan 40
Switch(config-vlan)#int g0/1
Switch(config-if)#switchport mode trunk
Switch(config-if)#switchport trunk allowed vlan all
Switch(config-if)#int f0/1
Switch(config-if)#switchport mode access
Switch(config-if)#switchport access vlan 30
Switch(config-if)#int f0/2
Switch(config-if)#switchport mode access
Switch(config-if)#switchport access vlan 40
