掌握交换机Tag VLAN 的配置；
掌握三层交换机基本配置方法；
掌握三层交换机VLAN路由的配置方法；
通过三层交换机实现VLAN间相互通信；
二、实验背景
某企业有两个主要部门，技术部和销售部，分处于不同的办公室，为了安全和便于管理，对两个部门的主机进行了VLAN的划分，技术部和销售部分处于不同的VLAN。现由于业务的需求，需要销售部和技术部的主机能够相互访问，获得相应的资源，两个部门的交换机通过一台三层交换机进行了连接。
三、技术原理
三层交换机具备网络层的功能，实现VLAN间相互访问的原理是：利用三层交换机的路由功能，通过识别数据包的IP地址，查找路由表进行选路转发。三层交换机利用直连路由可以实现不同VLAN之间的互相访问。三层交换机给接口配置IP地址，采用SVI(交换虚拟接口)的方式实现VLAN间互连。SVI是指为交换机中的VLAN创建虚拟接口，并且配置IP地址。
四、实验步骤
实验拓扑
1、在二层交换机上配置VLAN 2、VLAN 3，分别将端口2、端口3划到VLAN 2、VLAN 3；
2、将二层交换机与三层交换机相连的端口Fa0/1定义为Tag VLAN模式；
Switch>en Switch#conf t Enter configuration commands, one per line. End with CNTL/Z. Switch(config)#vlan 2 Switch(config-vlan)#exit Switch(config)#vlan 3 Switch(config-vlan)#exit Switch(config)#interface fa0/2 Switch(config-if)#switchport access vlan 2 Switch(config-if)#exit Switch(config)#interface fa0/3 Switch(config-if)#switchport access vlan 3 Switch(config-if)#exit Switch(config)#interface fa0/1 Switch(config-if)#switchport mode trunk %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)#
3、在三层交换机上配置VLAN 2、VLAN 3，分别将端口2、端口3划到VLAN 2、VLAN 3；
Switch>en Switch#conf t Enter configuration commands, one per line. End with CNTL/Z. Switch(config)#vlan 2 Switch(config-vlan)#exit Switch(config)#vlan 3 Switch(config-vlan)#exit Switch(config)#interface fa0/2 Switch(config-if)#switchport access vlan 2 Switch(config-if)#exit Switch(config)#interface fa0/3 Switch(config-if)#switchport access vlan 3 Switch(config-if)#exit Switch(config)#
4、设置三层交换机VLAN间通信，创建VLAN 2、VLAN 3的虚拟接口，并配置虚拟接口VLAN 2、VLAN 3的IP地址；
Switch(config)#interface vlan 2 //创建 VLAN 2 的虚拟接口 Switch(config-if)# %LINK-5-CHANGED: Interface Vlan2, changed state to up %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan2, changed state to up Switch(config-if)#ip address 192.168.1.1 255.255.255.0 //配置虚拟接口 VLAN 2 的IP地址 Switch(config-if)#no shutdown Switch(config-if)#exit Switch(config)#interface vlan 3 //创建 VLAN 2 的虚拟接口 Switch(config-if)# %LINK-5-CHANGED: Interface Vlan3, changed state to up %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan3, changed state to up Switch(config-if)#ip address 192.168.2.1 255.255.255.0 //配置虚拟接口 VLAN 2 的IP地址 Switch(config-if)#no shutdown Switch(config-if)#exit Switch(config)#ip routing ！开启三层交换机路由功能 Switch(config)#end Switch#
5、查看三层交换机路由表
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, Vlan2 C 192.168.2.0/24 is directly connected, Vlan3 Switch#
6、将VLAN 2、VLAN 3下的主机默认网关分别设置为相应虚拟接口的IP地址；
五、验证
打开PC1 Command Prompt
Packet Tracer PC Command Line 1.0 PC>ipconfig IP Address......................: 192.168.1.2 Subnet Mask.....................: 255.255.255.0 Default Gateway.................: 192.168.1.1 PC>ping 192.168.1.3 Pinging 192.168.1.3 with 32 bytes of data: Reply from 192.168.1.3: bytes=32 time=187ms TTL=128 Reply from 192.168.1.3: bytes=32 time=93ms TTL=128 Reply from 192.168.1.3: bytes=32 time=110ms TTL=128 Reply from 192.168.1.3: bytes=32 time=93ms TTL=128 Ping statistics for 192.168.1.3: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 93ms, Maximum = 187ms, Average = 120ms PC>ping 192.168.2.2 Pinging 192.168.2.2 with 32 bytes of data: Request timed out. Reply from 192.168.2.2: bytes=32 time=188ms TTL=127 Reply from 192.168.2.2: bytes=32 time=112ms TTL=127 Reply from 192.168.2.2: bytes=32 time=125ms TTL=127 Ping statistics for 192.168.2.2: Packets: Sent = 4, Received = 3, Lost = 1 (25% loss), Approximate round trip times in milli-seconds: Minimum = 112ms, Maximum = 188ms, Average = 141ms PC>ping 192.168.2.3 Pinging 192.168.2.3 with 32 bytes of data: Request timed out. Reply from 192.168.2.3: bytes=32 time=125ms TTL=127 Reply from 192.168.2.3: bytes=32 time=78ms TTL=127 Reply from 192.168.2.3: bytes=32 time=64ms TTL=127 Ping statistics for 192.168.2.3: Packets: Sent = 4, Received = 3, Lost = 1 (25% loss), Approximate round trip times in milli-seconds: Minimum = 64ms, Maximum = 125ms, Average = 89ms
