菜鸟知识：如何配置STP的方法合集（二）

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拓扑图

图1 配置STP实验拓扑图

场景：上一集我们讲到如何配置STP并验证，那接下来我们将继续下一个步骤：控制根桥选举。

控制根桥选举

执行display stp命令查看根桥信息。根桥设备的CIST Bridge与CIST Root/ERPC字段取值相同。

[SW1]display stp

-------CIST Global Info-------

CIST Bridge :0 .4c1f-cc16-05ac <本交换机SW1的网桥ID>

Config Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20

Active Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20

CIST Root/ERPC :0 .4c1f-cc16-05ac / 0 <本设备SW1为根交换机>

CIST RegRoot/IRPC :0 .4c1f-cc16-05ac / 0

CIST RootPortId :0.0

BPDU-Protection :Disabled

CIST Root Type :Primary root

TC or TCN received :8

TC count per hello :0

STP Converge Mode :Normal

Time since last TC :0 days 0h:24m:37s

……output omit……

[SW2]display stp

-------CIST Global Info-------

CIST Bridge :4096 .4c1f-cc78-50fb <本交换机SW2的网桥ID>

Config Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20

Active Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20

CIST Root/ERPC :0 .4c1f-cc16-05ac / 20000 <在SW2上看到SW1为根交换机>

CIST RegRoot/IRPC :4096 .4c1f-cc78-50fb / 0

CIST RootPortId :128.9

BPDU-Protection :Disabled

CIST Root Type :Secondary root

TC or TCN received :43

TC count per hello :0

STP Converge Mode :Normal

Time since last TC :0 days 0h:26m:12s

……output omit……

以上回显表示SW1为根桥，SW2为备份根桥。

通过配置优先级，使SW2为根桥，SW1为备份根桥。桥优先级取值越小，则优先级越高。把SW1和SW2的优先级分别设置为8192和4096。

配置SW1：

[SW1]undo stp root

[SW1]stp priority 8192

配置SW2：

[SW2]undo stp root

[SW2]stp priority 4096

执行display stp命令查看新的根桥信息。

[SW1]display stp

-------CIST Global Info-------

CIST Bridge :8192 .4c1f-cc16-05ac

Config Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20

Active Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20

CIST Root/ERPC :4096 .4c1f-cc78-50fb / 20000

CIST RegRoot/IRPC :8192 .4c1f-cc16-05ac / 0

CIST RootPortId :128.33

BPDU-Protection :Disabled

TC or TCN received :24

TC count per hello :2

STP Converge Mode :Normal

Time since last TC :0 days 0h:0m:16s

……output omit……

[SW2]display stp

-------CIST Global Info-------

CIST Bridge :4096 .4c1f-cc78-50fb

Config Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20

Active Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20

CIST Root/ERPC :4096 .4c1f-cc78-50fb / 0

CIST RegRoot/IRPC :4096 .4c1f-cc78-50fb / 0

CIST RootPortId :0.0

BPDU-Protection :Disabled

TC or TCN received :43

TC count per hello :0

STP Converge Mode :Normal

Time since last TC :0 days 0h:0m:52s

……output omit……

由上述回显信息中的灰色部分可以看出，SW2已经变成新的根桥。

关闭SW2的G0/0/9和G0/0/10端口，从而隔离SW1与SW2，模拟SW2发生故障。

[SW2]interface GigabitEthernet 0/0/9

[SW2-GigabitEthernet0/0/9]shutdown

[SW2-GigabitEthernet0/0/9]quit

[SW2]interface GigabitEthernet 0/0/10

[SW2-GigabitEthernet0/0/10]shutdown

[SW1]display stp

-------CIST Global Info-------

CIST Bridge :8192 .4c1f-cc16-05ac

Config Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20

Active Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20

CIST Root/ERPC :8192 .4c1f-cc16-05ac / 0

CIST RegRoot/IRPC :8192 .4c1f-cc16-05ac / 0

CIST RootPortId :0.0

BPDU-Protection :Disabled

TC or TCN received :43

TC count per hello :0

STP Converge Mode :Normal

Time since last TC :0 days 0h:9m:17s

……output omit……

在上述回显信息中，灰色部分表明当SW2故障时，SW1变成根桥，然后开启SW2之前关闭的接口。

[SW2]interface GigabitEthernet 0/0/9

[SW2-GigabitEthernet0/0/9]undo shutdown

[SW2-GigabitEthernet0/0/9]quit

[SW2]interface GigabitEthernet 0/0/10

[SW2-GigabitEthernet0/0/10]undo shutdown

[SW1]display stp

-------CIST Global Info-------

CIST Bridge :8192 .4c1f-cc16-05ac

Config Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20

Active Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20

CIST Root/ERPC :4096 .4c1f-cc78-50fb / 20000

CIST RegRoot/IRPC :8192 .4c1f-cc16-05ac / 0

CIST RootPortId :128.33

BPDU-Protection :Disabled

TC or TCN received :54

TC count per hello :0

STP Converge Mode :Normal

Time since last TC :0 days 0h:0m:14s

……output omit……

[SW2]display stp

-------CIST Global Info-------

CIST Bridge :4096 .4c1f-cc78-50fb

Config Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20

Active Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20

CIST Root/ERPC :4096 .4c1f-cc78-50fb / 0 <SW2为根桥>

CIST RegRoot/IRPC :4096 .4c1f-cc78-50fb / 0

CIST RootPortId :0.0

BPDU-Protection :Disabled

TC or TCN received :45

TC count per hello :0

STP Converge Mode :Normal

Time since last TC :0 days 0h:0m:43s

……output omit……

在上述回显信息中，灰色部分表明SW2已经恢复正常，重新变成根桥。

下集预告： 控制根端口选举，明天更新