三层交换机与路由器的配置 实例（图解）
目的：学会使用三层交换与路由器让处于不同网段的网络相互通信
实验步骤：一：二层交换机的配置：
在三个二层交换机上分别划出两VLAN，并将二层交换机上与三层交换或路由器上的接线设置为trunk接口
二：三层交换机的配置：
1：首先在三层交换上划出两个VLAN，并进入VLAN为其配置IP，此IP将作为与他相连PC的网关。
react router switch2：将与二层交换机相连的线同样设置为trunk接线，并将三层交换与路由器连接的线设置为路由接口（no switchsport）
3：将路由器和下面的交换机进行单臂路由的配置
实验最终结果：拓扑图下各个PC均能相互通信
交换机的配置命令：
SW 0:
Switch>
Switch>en
Switch#conf
Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)#vlan 2
Switch(config-vlan)#exit
Switch(config)#int f0/2
Switch(config-if)#switchport access vlan 2
Switch(config-if)#no shut
Switch(config-if)#int f0/3
Switch(config-if)#switchport mode trunk
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to up
Switch(config-if)#exit
Switch(config)#
SW 1:
Switch>en
Switch#conf
Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)#int f0/2
Switch(config-if)#switchport access vlan 2
% Access VLAN does not exist. Creating vlan 2
Switch(config-if)#no shut
Switch(config-if)#exit
Switch(config)#int f0/3
Switch(config-if)#switchport mode trunk
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to up
Switch(config-if)#
SW 2:
Switch>en
Switch#conf
Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)#int f0/2
Switch(config-if)#switchport access vlan 2
% Access VLAN does not exist. Creating vlan 2
Switch(config-if)#exit
Switch(config)#int f0/3
Switch(config-if)#switchport mode trunk
Switch(config-if)#
三层交换的配置命令：
Switch>en
Switch#conf
Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)#int f0/1
Switch(config-if)#switchport mode trunk
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to down
Switch(config-if)#exit
Switch(config)#int f0/2
Switch(config-if)#switchport mode trunk
Switch(config-if)#exit
Switch(config)#vlan 2
Switch(config-vlan)#exit
Switch(config)#int vlan 1
Switch(config-if)#no shut
%LINK-5-CHANGED: Interface Vlan1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to up
Switch(config-if)#ip address 192.168.1.168 255.255.255.0
Switch(config-if)#exit
Switch(config)#int vlan 2
%LINK-5-CHANGED: Interface Vlan2, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan2, changed state to upSwitch(config-if)#ip add
Switch(config-if)#ip address 192.168.2.168 255.255.255.0
Switch(config-if)#
%LINK-5-CHANGED: Interface FastEthernet0/3, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to up
Switch(config-if)#exit
Switch(config)#int f0/3
Switch(config-if)#no switchport
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to upSwitch(config-if)#
Switch(config-if)#ip address 192.168.10.1 255.255.255.0
Switch(config-if)#no shut
Switch(config-if)#exit
Switch(config)#ip routing
Switch(config-if)#exit
Switch(config)#ip route 0.0.0.0 0.0.0.0 192.168.10.2
Switch(config)#
路由器的配置：
Router>en
Router#conf
Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#int f0/0
Router(config-if)#no shut
%LINK-5-CHANGED: Interface FastEthernet0/0, changed state to up
Router(config-if)#exit
Router(config)#int f0/1
Router(config-if)#no shut
%LINK-5-CHANGED: Interface FastEthernet0/1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up
Router(config-if)#exit
Router(config)#int f0/0
Router(config-if)#no shut
Router(config-if)#exit
Router(config)#int f0/0.1
Router(config-subif)#encapsulation dot1Q 1
Router(config-subif)#ip address 192.168.3.168 255.255.255.0
Router(config-subif)#exit
Router(config)#int f0/0.2
Router(config-subif)#encapsulation dot1Q 2
Router(config-subif)#ip add
Router(config-subif)#ip address 192.168.4.168 255.255.255.0
Router(config-subif)#exit
Router(config)#ip route 0.0.0.0 0.0.0.0 192.168.10.1
Router(config)#exit
%SYS-5-CONFIG_I: Configured from console by console
Router#conf
Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#int f0/1
Router(config-if)#ip add
Router(config-if)#ip address 192.168.10.2 255.255.255.0
Router(config-if)#

我不知道为什么你要在三层交换机上把f0/1划入vlan 10、f0/2划入vlan 20
我觉得你这样做是完全多余的
你试试去掉在SWA上配置的“把f0/1划入vlan 10、f0/2划入vlan 20”
然后看看能否通信了
我的配置是：
三层交换机（就是你的SA）：
Switch>en      //进入特权模式
Switch#conf t    //进入全局模式
Switch(config)#in f0/24  //进入f0/24接口
Switch(config-if)#sw mo tr  //启用trunk
Switch#vlan da    //进入vlan数据库模式
Switch(vlan)#vlan 10  //创建valn 10
Switch(vlan)#vlan 20  //创建valn 20
Switch(vlan)#ex          //退出vlan数据库模式
Switch#conf t
Switch(config)#in vlan 10    //进入vlan 10
Switch(config-if)#ip add 192.168.10.254 255.255.255.0  //配置IP
Switch(config-if)#no sh  //启用
Switch(config-if)#ex  //退出
Switch(config)#in vlan 20
Switch(config-if)#ip add 192.168.20.254 255.255.255.0
Switch(config-if)#no sh
二层交换（就是你的SB）：
Switch>en
Switch#conf t
Switch(config)#in f0/24
Switch(config-if)#sw mo tr
Switch#vlan da
Switch(vlan)#vlan 10
Switch(vlan)#vlan 20
Switch(vlan)#ex
Switch#conf t
Switch(config)#in f0/23
Switch(config-if)#sw acc vlan 10 
Switch(config-if)#sw mo acc
Switch(config-if)#ex
Switch(config)#in f0/22
Switch(config-if)#sw acc vlan 10
Switch(config-if)#sw mo acc
Switch(config-if)#ex
Switch(config)#in f0/21
Switch(config-if)#sw acc vlan 20
Switch(config-if)#sw mo acc
PC1：
PC>ipconfig
: 192.168.10.111
: 255.255.255.0
: 192.168.10.254
PC2:
PC>ipconfig
: 192.168.10.222
: 255.255.255.0
: 192.168.10.254
PC3:
PC>ipconfig
: 192.168.20.111
: 255.255.255.0
: 192.168.20.254
经测试：  pc1  ping pc3是通的  任何一台PC都能PING通网关和其他PC