第7章 广播风暴接STP

1.交换机关闭STP协议

[SW1]stp disable 
[SW2]stp disable 
[SW3]stp disable 

2.PC1连通未知IP地址

PC1>ping 192.168.1.3
Ping 192.168.1.3: 32 data bytes, Press Ctrl_C to break
From 192.168.1.1: Destination host unreachable

3.在SW1、SW2之间抓包，产生大量arp报文

4.交换机发现有MAC地址漂移日志

[SW2]
Feb  1 2023 21:46:27-08:00 SW2 DS/4/DATASYNC_CFGCHANGE:OID 1.3.6.1.4.1.2011.5.25.191.3.1 configurations have been changed. The current change number is 5, the change loop count is 0, and the maximum number of records is 4095.
Feb  1 2023 21:49:24-08:00 SW2 L2IFPPI/4/MFLPVLANALARM:OID 1.3.6.1.4.1.2011.5.25.160.3.7 MAC move detected, VlanId = 1, MacAddress = 5489-9840-2b6f, Original-Port = GE0/0/2, Flapping port = GE0/0/1 and GE0/0/3. Please check the network accessed to flapping port.

5.三台交换机开启STP协议，设置为stp模式（默认mstp模式）

[SW1]stp enable
[SW1]stp mode stp 

[SW2]stp enable
[SW2]stp mode stp 

[SW3]stp enable
[SW3]stp mode stp 

6.查看交换机MAC地址

[SW1]display interface
Hardware address is 4c1f-cc34-1a04
[SW2]display interface 
Hardware address is 4c1f-cc2c-66b5
[SW3]display  interface 
Hardware address is 4c1f-cceb-7e9b

7.查看STP信息，SW2成根交换机（MAC地址小）

[SW1]display stp
CIST Root/ERPC      :32768.4c1f-cc2c-66b5 / 20000
[SW2]display stp
CIST Root/ERPC      :32768.4c1f-cc2c-66b5 / 0
[SW3]display  stp     
CIST Root/ERPC      :32768.4c1f-cc2c-66b5 / 20000

8.查看交换机角色

[SW1]display stp brief 
 MSTID  Port                        Role  STP State     Protection
   0    GigabitEthernet0/0/1        ROOT  FORWARDING      NONE
   0    GigabitEthernet0/0/2        DESI  FORWARDING      NONE

[SW2]display stp brief 
0    GigabitEthernet0/0/1        DESI  FORWARDING      NONE
   0    GigabitEthernet0/0/2        DESI  FORWARDING      NONE
   0    GigabitEthernet0/0/3        DESI  FORWARDING      NONE

[SW3]display stp brief
0    GigabitEthernet0/0/1        DESI  FORWARDING      NONE
   0    GigabitEthernet0/0/2        ALTE  DISCARDING      NONE
   0    GigabitEthernet0/0/3        ROOT  FORWARDING      NONE

9.修改SW1交换机优先级，使SW1成为根桥

[SW1]stp priority 4096

10.查看交换机角色，SW1成为根桥

[SW1]display stp
CIST Root/ERPC      :4096 .4c1f-cc34-1a04 / 0
[SW2]display stp
CIST Root/ERPC      :4096 .4c1f-cc34-1a04 / 20000
[SW3]display stp     
CIST Root/ERPC      :4096 .4c1f-cc34-1a04 / 20000