CISCO中生成树协议的配置

1、实验一生成树（STP）一、实验目的1）：本实验的目的是通过配置以下三种拓朴图，让我们对生成树的工作原理有更 深的认识。2）:掌握生成树在交换机上的配置方法，对生成树在网络上的应用有更深的了解二、实验要求：1）：简述生成树协议的三个前提。2）:简述根桥、根端口、指定端口的选举原则。三、实验内容：1、通过三种拓朴图来研究根桥、根端口、指定端口选举方法；2、根桥、根端口、指定端口查看方法四、实验步骤：第一种：实验拓朴：1）查看三台交换机那个台是根桥在交换机上使用命令show spanning-tree vlan 1或 show spanning-tree brif可以查看当前网络中的根桥、根端口、指

2、定端口。如下：Sfflttsh spanning-tree briRoot IDPriori ty Address This bridge Hello Time32768ccOO. Oa30. 0000 is the root2 sec Max Age 20 secForward Delay 15Bridge IDPriori ty32768AddressccOO. Da3D. 0000Hello Time2 sec Max Age 20 secForward Delay 15Aging Time300InterfaceDesignatedNameFort ID Prio Cost Sts C

3、ostBridge IDtree enabled protocol ieeesecsecVLAN1SpanningPort IDFastEthernetO/1Fas tE theme tO/2128,2128128.312819 FWD19 FWD0 32768 ccOO. 0a30. 0000 128.20 32768 ccOO. Da3D. 0000 128.3Spanning Root IDtree enabled protocol ieeeForward Delay 15 secPriorityAddressCostPortHello Time32768CCOO. 0a30. 0000

4、192 (FastEthernetO/1)2 sec Max Age 20 secBridge IDPriori ty32768AddressccOO. 0f90. 0000Hello Time2 sec Max Age 20 secForward Delay 15 aecAging Time300SW2ttsh spanning-tree briVLAN1J.nt erfaceNameDes ignaPort ID Prio CostSts Cost Bridge IDPort ID精选资料，欢迎下载FastEthernetO/1HastEthernetO/2128. 212819 FWD0

5、 32768 ccOO. 0a30+ 0000 128. 2128.312819 BLK19 32768 ccOO. 0c24. 0000 128. 3可以看出SW为根桥，SW2为非根桥，用同样的命令查看第三台交换机。2)现在修改SW2的优先级让它成为根桥在交换机上使用此命令spa nnin g-tree vlan 1 priority 4096SW2(co nfig)# spa nnin g-tree vlan 1 priority 4096SW2#sh spanning-tree bri查看 spanning-treeSff2fish spanning-tree briVLAN1Spann

6、ing tree enabled protocol ieeeRoot IDPriority4096AddressccOO. 0f9D. 0000This bridgeis th巳 rootHello Time2 sec Man Age 20 secForward Delay 15 secBridge IDPriority4096AddressccOO. 0f90.0000Hello Time2 sec Max Age 20 secForward Delay 15 secAging Time 300InterfaceDesignatedNamePo讥 ID Prio Cost Sts Cost

7、Bridge IDPort IDFastEthernetO/1128.212819 FW04096 ccOO. 0f90. 0000 128.2F/tEth陆netQ/2128/12819 F刖04096 cMO. Qf90.0000 128.3第二种：实验拓朴InterfacelameDesignaPort ID Prio Cost Sts Cost Bridge IDPort ID1）查看二台交换机那个台是根桥在交换机上使用命令show spanning-treevlan 1 或 show spanning-treebrif可以查看当前网络中的根桥、根端口、指定端口。SI2ltsh spa

8、nning一tree briVLAN1Spanning tree enabled protocol ieeeRoot IDPriorityAddressCostPoriHello Time32768bccOO, 0380. OOOdf192 (FastEthernetO/1)2 sec May Age 20 secFonrard Delay 15 secBridge IDPriority32768AddressccOO. 10e8, 0000Hello Time2 sec May Age 20 secForward Delay 15 secAging Time300FastEthernetO/

9、1128.212819 FVD0 32766 ccOO. 0380,0000128.2FastEthernetO/2128.312819 BLK0 32768 ccOO. 0380.0000128.3可以看到交换机 SW2上的FO/1是转发状态，F0/2是阻断状态。2 )指定为根端口方法有：a:改变接口上的cost值(在本端修改)命令为 spanning-tree vlan 1 cost 20b:改变发送者接口上ID值(在对端修改)命令为 spanning-tree vlan 1 port-priority 96注：port-priority 后的值是16倍数c:在物理上改变在这就不作详解了。

10、3 )步聚如下：第一种方法：在本端修改接口cost值SW2(co nfig)# int fa0/1SW2(co nfig-if)# spa nnin g-tree vlan 1 cost 20SW2#sh spa nnin g-tree briSV2#sh spanningstree briVLAN1Spanning tree enabled protocol ieeeRoot IDPriority32768AddressccOO. laic. 0000Cost19Port3 (FastEthernetO/2)Hello Time2 sec Mas Age 20 secForward Dela

11、y15 secBridge IDPriority32768AddressccOO. la4B. DODOHello Time2 sec Max Age 20 secForward Delay15 secAging Time 300InterfaceDesignatedPort ID128.2128.3NamePort ID Prio Cost Sts Cost Bridge IDFastEthernetO/1128*212820 BLK0 32768 ccOO. laic* 0000FastEthernetO/2128.312819 FWD0 32768 ccOO. laic. 0000第二种方法：在对端修改发送者接口ID值SW1(config ) #int faO/2SW1 (con fig-if)#spa nnin g-tree vla n 1 priority 96SW2#sh spanning-tree bri (在对端查看)第三种：实