实验三STP.docx

1、实验三STP实验三 ：STP一：实验目标1 组网要求：此阿勇两台核心交换机组网来提高网络可靠性，为防止二层环路，需要全网运行STP：将SW1部署为根网桥，SW2部署为备份网桥，并将接入PC的接口配置为portfast端口。2 分析STP选举过程（根网桥、根端口、指定端口、阻塞端口）。二：拓扑图三：预期结果 对于vlan8和vlan10 ，SW3的FA0/2口是阻塞的，对于vlan11，SW3的FA0/1口是阻塞的。四：调试SW3上STP配置：SW1上STP配置：SW2上STP配置：五：测试SW3上show spanning-tree bri:Vlan8:Vlan 10:Vlan 11:Pc2

2、ping pc1:六：总结与原理分析Pc1 ping pc2数据流分析：1 Pc1封装icmp包，发现未知目的mac地址且目的IP与自己不在同一个网段，则封装一个arp请求，请求的目的IP为网关IP，目的mac为全F；2 在通过fa0/10口时，arp请求被打上了vlan10 的标签；3 进入sw3，sw3查询mac地址表，发现没有pc1 的mac地址，便更新mac表；4 由于配置了生成树协议，相对于vlan10，sw3的fa0/2口是阻塞的，所以arp请求被 交换机从fa0/1口发送到三层交换机sw1；5 Sw1收到arp请求后，发现目的ip是自身的，然后拆vlan10标，更新mac地址表，

3、便封装一个arp应答，封装时打上vlan10的标， 从fa0/3口单播出去；6 Sw3收到arp应答，查询mac地址表后，从fa0/10转发出去，在出口拆掉vlan10的标签；7 Pc1收到arp应答，更新自身的arp缓存表，重新封装icmp包，其目的mac是网关，目的IP是pc2的IP地址，将封装好的icmp包，通过fa0/10口送往SW3；8 Icmp包在fa0/10口被打上vlan10的标签；9 Icmp包进入sw3，sw3查询mac地址表，把icmp包从fa0/1口转发出去；10 SW1收到icmp包，拆vlan10标，发现目的IP地址不是自己的，但是网关却是已知的vlan11，且不知

4、道目的mac地址，便封装一个arp请求，并打上vlan11的标签，洪泛出去；11 由于配置了生成树协议，SW3的fa0/1口相对于vlan11是阻塞的，所以arp请求从sw1的fa0/1口发送到sw2的fa0/1口；12 Sw2收到arp请求后，更新自己的mac地址表，从fa0/3口发送出去，到sw3的fa0/2口；13 Arp请求从sw3 的fa0/2进入sw3，sw3更新自己的mac地址表，将arp请求从fa0/11口洪泛出去；14 在通过fa0/11口时，arp请求被拆掉了vlan11的标签，进入到pc2；15 Pc2收到arp请求后，更新自己的arp缓存表，打开arp请求，查看后，发出

5、arp应答；16 Arp应答在经过fa0/11口时，被打上了vlan11的标签；17 Sw3收到arp应答后，更新自身的mac地址表，再查询mac地址表，从fa0/2口转发arp应答给SW2；18 Sw2收到arp应答后，更新自身的mac地址表，再查询mac地址表，从fa0/1口转发给sw1；19 Sw1收到arp应答后，拆掉vlan11的标签，更新mac地址表，重新封装icmp包，并打上vlan11的标签，从fa0/1口转发给sw2；20 Sw2收到icmp包后，查询mac地址表，从fa0/3转发icmp包到sw3；21 Sw3收到icmp包后，查询mac地址表，从fa0/11转发icmp包

6、到pc2；22 Icmp包在经过接口fa0/11时，被拆掉vlan11的标签；23 Pc2收到icmp包后，发现目的IP是自己的，目的mac是自己的，打开icmp包，然后封装一个icmp回应包；24 Icmp回应包在链路中一直被转发其路径是：PC2SW3SW2SW1SW3PC1。七：配置show runSW1:!version 12.3service timestamps debug datetime msecservice timestamps log datetime msecno service password-encryption!hostname SW1!boot-start-ma

7、rkerboot-end-marker!no aaa new-model!resource policy!memory-size iomem 5ip subnet-zero!ip cefno ip dhcp use vrf connected!no ip domain lookupno ftp-server write-enable!spanning-tree vlan 8 priority 0spanning-tree vlan 10 priority 0spanning-tree vlan 11 priority 4096!interface FastEthernet0/0!interfa

8、ce FastEthernet0/1 switchport mode trunk!interface FastEthernet0/2!interface FastEthernet0/3 switchport mode trunk!interface FastEthernet0/4!interface FastEthernet0/5!interface FastEthernet0/6!interface FastEthernet0/7!interface FastEthernet0/8!interface FastEthernet0/9!interface FastEthernet0/10!in

9、terface FastEthernet0/11!interface FastEthernet0/12!interface FastEthernet0/13!interface FastEthernet0/14!interface FastEthernet0/15!interface Vlan1 no ip address!interface Vlan8 ip address 192.168.8.129 255.255.255.128!interface Vlan10 ip address 192.168.10.1 255.255.255.0!interface Vlan11 ip addre

10、ss 192.168.11.1 255.255.255.0!ip http serverip classless!control-plane!line con 0 exec-timeout 0 0 logging synchronousline aux 0line vty 0 4!EndSW2:!version 12.3service timestamps debug datetime msecservice timestamps log datetime msecno service password-encryption!hostname SW2!boot-start-markerboot

11、-end-marker!no aaa new-model!resource policy!memory-size iomem 5ip subnet-zero!ip cefno ip dhcp use vrf connected!no ip domain lookupno ftp-server write-enable!spanning-tree vlan 8 priority 4096spanning-tree vlan 10 priority 4096spanning-tree vlan 11 priority 0!interface FastEthernet0/0!interface Fa

12、stEthernet0/1 switchport mode trunk!interface FastEthernet0/2!interface FastEthernet0/3 switchport mode trunk!interface FastEthernet0/4!interface FastEthernet0/5!interface FastEthernet0/6!interface FastEthernet0/7!interface FastEthernet0/8!interface FastEthernet0/9!interface FastEthernet0/10!interfa

13、ce FastEthernet0/11!interface FastEthernet0/12!interface FastEthernet0/13!interface FastEthernet0/14!interface FastEthernet0/15!interface Vlan1 no ip address!interface Vlan8 ip address 192.168.8.130 255.255.255.128!ip default-gateway 192.168.8.129ip http serverip classless!control-plane!line con 0 e

14、xec-timeout 0 0 logging synchronousline aux 0line vty 0 4!EndSW3:!version 12.3service timestamps debug datetime msecservice timestamps log datetime msecno service password-encryption!hostname SW3!boot-start-markerboot-end-marker!no aaa new-model!resource policy!memory-size iomem 5ip subnet-zero!ip c

15、efno ip dhcp use vrf connected!no ip domain lookupno ftp-server write-enable!interface FastEthernet0/0!interface FastEthernet0/1 switchport mode trunk!interface FastEthernet0/2 switchport mode trunk!interface FastEthernet0/3!interface FastEthernet0/4!interface FastEthernet0/5!interface FastEthernet0

16、/6!interface FastEthernet0/7!interface FastEthernet0/8!interface FastEthernet0/9!interface FastEthernet0/10 switchport access vlan 10 spanning-tree portfast!interface FastEthernet0/11 switchport access vlan 11 spanning-tree portfast!interface FastEthernet0/12!interface FastEthernet0/13!interface FastEthernet0/14!interface FastEthernet0/15!interface Vlan1 no ip address!interface Vlan8 ip address 192.168.8.132 255.255.255.128!ip default-gateway 192.168.8.129ip http serverip classless!control-plane!line con 0 exec-timeout 0 0 logging synchronousline aux 0line vty 0 4!end