问题

三层交换机实现了VLAN间互通后，还要与其他网络进行通信，这样就需要有相关的路由机制。

交换接口配置为三层接口实现路由间通信

方案

三层交换机既然具有三层功能，也就可以实现与路由器相似的配置。既可以把交换接口配置为三层接口，也可以在其上配置静态、动态路由。通过对三层交换机的路由配置，实现VLAN与其他网络的互通。

拓扑图

步骤

1.配置三层交换机

三层交换机创建vlan并配置vlan的虚端口IP并开启路由功能

Switch>enable

Switch#configure terminal

Switch(config)#vlan 2

Switch(config-vlan)#vlan 3

Switch(config-vlan)#vlan 4

Switch(config-vlan)#vlan 5

Switch(config)#interface vlan 1

Switch(config-if)#ip address 192.168.1.254 255.255.255.0

Switch(config-if)#no shutdown

Switch(config)#interface vlan 2

Switch(config-if)#ip address 192.168.2.254 255.255.255.0

Switch(config-if)#no shutdown

Switch(config)#interface vlan 3

Switch(config-if)#ip address 192.168.3.254 255.255.255.0

Switch(config-if)#no shutdown

Switch(config)#interface vlan 4

Switch(config-if)#ip address 192.168.4.254 255.255.255.0

Switch(config-if)#no shutdown

Switch(config)#interface vlan 5

Switch(config-if)#ip address 192.168.5.254 255.255.255.0

Switch(config-if)#no shutdown

Switch(config)#ip routing //开启路由功能

三层交换的Fa0/23、Fa0/24设置为中继链路模式

Switch(config)#interface range f0/23-24

Switch (config-if-range)#switchport trunk encapsulation dot1q

Switch (config-if-range)#switchport mode trunk

2.配置二层交换机

Sw1创建vlan2、 vlan3并将端口加入vlan

Sw1(config)#vlan 2

Sw1(config)#vlan 2

Sw1(config-vlan)#vlan 3

Sw1(config)#interface fastEthernet 0/2

Sw1(config-if)#switchport access vlan 2

Sw1(config)#interface fastEthernet 0/3

Sw1(config-if)#switchport access vlan 3

Sw1(config)#interface fastEthernet 0/5

Sw1(config-if)#switchport mode trunk //连接三层交换机的接口配置为trunk模式

Sw2创建vlan4、 vlan5并将端口加入vlan

Sw2(config)#vlan 4

Sw2(config-vlan)#vlan 5

Sw2(config)#interface fastEthernet 0/1

Sw2(config-if)#switchport access vlan 4

Sw2(config)#interface f0/2

Sw2(config-if)#switchport access vlan 5

3.将三层交换的Fa0/6口配置为三层路由端口，并配置IP地址

三层交换机的物理端口默认是二层端口，只具有二层特性，不能配置IP地址。把二层端口配置为三层端口后，该端口就具备路由功能了，可以配置IP地址，但同时也就关闭了其二层特性，比如不能把三层端口加入VLAN。

二层端口(交换机上的端口默认都是二层端口)默认是激活状态，那些没有使用到的端口为了安全应该手工将其禁用(shutdown)；而三层端口(路由器上的端口或是三层交换机上被配置成路由端口的端口)默认是禁用状态，在使用之前务必要将其激活(no shutdown)。

Switch(config)#interface f0/6

Switch(config-if)#no switchport

Switch(config-if)#ip address 192.168.6.1 255.255.255.0

Switch(config-if)#no shutdown

4.配置路由器的端口IP地址

Switch(config)#interface f0/0

Switch(config-if)#ip address 192.168.6.2 255.255.255.0

Switch(config-if)#no shutdown

Switch(config-if)#interface f0/1

Switch(config-if)#ip address 192.168.7.254 255.255.255.0

Switch(config-if)#no shutdown

5.在三层交换机上配置静态路由，以便VLAN内主机可以与外界网络互联

Switch(config)#iproute 192.168.7.0 255.255.255.0 192.168.6.2 //格式 ip route 下一跳

Switch(config)#exit

Switch#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 192.168.1.0/24 is directly connected, Vlan1

C 192.168.2.0/24 is directly connected, Vlan2

C 192.168.3.0/24 is directly connected, Vlan3

C 192.168.4.0/24 is directly connected, Vlan4

C 192.168.5.0/24 is directly connected, Vlan5

C 192.168.6.0/24 is directly connected, FastEthernet0/6

S 192.168.7.0/24 [1/0] via 192.168.6.2

6.在路由器上配置到达三个VLAN网络的静路由

tarena-rouer(config)#ip route 192.168.1.0 255.255.255.0 192.168.6.1

tarena-rouer(config)#ip route 192.168.2.0 255.255.255.0 192.168.6.1

tarena-rouer(config)#ip route 192.168.3.0 255.255.255.0 192.168.6.1

tarena-rouer(config)#ip route 192.168.4.0 255.255.255.0 192.168.6.1

tarena-rouer(config)#ip route 192.168.5.0 255.255.255.0 192.168.6.1

tarena-rouer(config)#exit

tarena-rouer#show ip rout

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

S    192.168.1.0/24 [1/0] via 192.168.6.1

S    192.168.2.0/24 [1/0] via 192.168.6.1

S    192.168.3.0/24 [1/0] via 192.168.6.1

S    192.168.4.0/24 [1/0] via 192.168.6.1

S    192.168.5.0/24 [1/0] via 192.168.6.1

C    192.168.6.0/24 is directly connected, FastEthernet0/0

C    192.168.7.0/24 is directly connected, FastEthernet0/1

7.在PC上测试与VLAN的连通性

PC>ipconfig

FastEthernet0 Connection:(default port)

Link-local IPv6 Address.........: FE80::2E0:8FFF:FE14:BB43

IP Address......................: 192.168.7.1

Subnet Mask.....................: 255.255.255.0

Default Gateway.................: 192.168.7.254

SERVER>ping 192.168.1.1

Pinging 192.168.1.1 with 32 bytes of data:

Request timed out.

Reply from 192.168.1.1: bytes=32 time=0ms TTL=126

Reply from 192.168.1.1: bytes=32 time=0ms TTL=126

Reply from 192.168.1.1: bytes=32 time=1ms TTL=126

Ping statistics for 192.168.1.1:

Packets: Sent = 4, Received = 3, Lost = 1 (25% loss),

Approximate round trip times in milli-seconds:

Minimum = 0ms, Maximum = 1ms, Average = 0ms

SERVER>ping 192.168.2.1

Pinging 192.168.2.1 with 32 bytes of data:

Reply from 192.168.2.1: bytes=32 time=0ms TTL=126

Reply from 192.168.2.1: bytes=32 time=0ms TTL=126

Reply from 192.168.2.1: bytes=32 time=0ms TTL=126

Reply from 192.168.2.1: bytes=32 time=0ms TTL=126

Ping statistics for 192.168.2.1:

Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),

Approximate round trip times in milli-seconds:

Minimum = 0ms, Maximum = 0ms, Average = 0ms

​

SERVER>ping 192.168.3.1

Pinging 192.168.3.1 with 32 bytes of data:

Reply from 192.168.3.1: bytes=32 time=1ms TTL=126

Reply from 192.168.3.1: bytes=32 time=0ms TTL=126

Reply from 192.168.3.1: bytes=32 time=0ms TTL=126

Reply from 192.168.3.1: bytes=32 time=0ms TTL=126

Ping statistics for 192.168.3.1:

Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),

Approximate round trip times in milli-seconds:

Minimum = 0ms, Maximum = 1ms, Average = 0ms