Spanning-treeProtocol实训

1、Spannin g-tree Protocol的基本原理的根桥选择原理的重新计算过程1.1实验目的：掌握 Spanning-tree Protocol1.2实验内容：掌握 Spanning-tree Protocol掌握 Spanning-tree Protocol1.3实验步骤：FA/07,FA/02Switch A FAWSVaighMhrouqh udbe Serial ca bleConsole Rol ever）Crossover cable a）如图所示构建拓扑图b）分别在主机上要 ping通各自的VLAN的地址和网关地址c）分别在switchA 和switchB 上用show i

2、n terface vlan 1命令检查若得到：vlan 1 is up, line protocol is up就对了d）分别在switchA 和switchB 上用show spanning-tree命令观察谁是根桥及端口的情况e）把MAC地址大的那台交换机的优先级改为4096，用以下命令：switch（c on fig）#spa nnin g-tree vla n 1 priority 4096switch（c on fig）#exitf）分别在switchA和switchB上用show spanning-tree命令观察谁是根桥及端口的情况g）把刚才优先级改为 4096的那台交换机的优

3、先级改为32768h）把switchA 的f0/2 端口拔掉i) 分别在 switchA 和 switchB 上用 show spanning-tree 命令观察谁是根桥及端口的 情况j) 把 switchA 的 f0/2 端口插好k) 再分别在 switchA 和 switchB 上用 show spanning-tree 命令观察谁是根桥及端口的 情况1.4 实验参考：1、在 switch A 和 switch B 上都用 sh spanning-tree, 出现 :SwitchA# sh spanning-treeVLAN0001Spanning tree enabled protoco

4、l ieeeRoot ID Priority 32769Address 000b.5f06.8c00This bridge is the rootHello Time 2 sec Max Age 20 sec Forward Delay 15 secBridge ID Priority 32769 (priority 32768 sys-id-ext 1)Address 000b.5f06.8c00Hello Time 2 sec Max Age 20 sec Forward Delay 15 secAging Time 300InterfacePort ID DesignatedPort I

5、DName Prio.Nbr Cost Sts Cost Bridge ID Prio.NbrFa0/2 128.2 19 FWD 0 32769 000b.5f06.8c00 128.2Fa0/5 128.5 19 FWD 0 32769 000b.5f06.8c00 128.5Fa0/7 128.7 19 FWD 0 32769 000b.5f06.8c00 128.7结论 :switch A 是根桥2、在 switchB 上修改优先级为 :4097, 然后在 sh spanning-tree, 出现SwitchA# sh spanning-treeVLAN0001Spanning tre

6、e enabled protocol ieeeRoot ID Priority 4097Address 000b.5f06.abc0Cost19Port2 (FastEthernet0/2)Hello Time 2 sec Max Age 20 sec Forward Delay 15 secBridge ID Priority 32769 (priority 32768 sys-id-ext 1) Address 000b.5f06.8c00Hello Time 2 sec Max Age 20 sec Forward Delay 15 secAging Time 15InterfacePo

7、rt ID DesignatedPort IDName Prio.Nbr Cost Sts Cost Bridge ID Prio.NbrFa0/2 128.2 19 FWD 0 4097 000b.5f06.abc0 128.2Fa0/5 128.5 19 BLK 0 4097 000b.5f06.abc0 128.5Fa0/7 128.7 19 FWD19 32769 000b.5f06.8c00 128.7 结论 :switch B 是根桥出现：3、将 switchA 上的 f0/2 上的断掉 , 再 sh spanning-tree, SwitchA# sh spanning-tree

8、VLAN0001Spanning tree enabled protocol ieeeRoot ID Priority 32769Address 000b.5f06.8c00This bridge is the rootHello Time 2 sec Max Age 20 sec Forward Delay 15 secBridge ID Priority 32769 (priority 32768 sys-id-ext 1)Address 000b.5f06.8c00Hello Time 2 sec Max Age 20 sec Forward Delay 15 secAging Time

9、 15InterfacePort ID Designated00:15:15: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to down Port IDName Prio.Nbr Cost Sts Cost Bridge ID Prio.NbrFa0/5 128.5 19 FWD 0 32769 000b.5f06.8c00 128.5Fa0/7 128.7 19 FWD 0 32769 000b.5f06.8c00 128.74、将 switchA 上的 f0/2 up, 再

10、sh spanning-tree, 出现 SwitchA# sh spanning-treeVLAN0001Spanning tree enabled protocol ieeeRoot ID Priority 32769Address 000b.5f06.8c00This bridge is the rootHello Time 2 sec Max Age 20 sec Forward Delay 15 secBridge ID Priority 32769 (priority 32768 sys-id-ext 1) Address 000b.5f06.8c00Hello Time 2 sec Max Age 20 sec Forward Delay 15 secAging Time 15InterfacePort ID DesignatedPort IDName Prio.Nbr Cost Sts Cost Bridge ID Prio.NbrFa0/2128.2 19 LIS 0 32769 000b.5f06.8c00 128.2Fa0/5128.5 19 FWD 0 32769 000b.5f06.8c00 128.5Fa0/7128.7 19 FWD 0 32769 0