S3700交换机单区域多生树故障

发布时间:  2017-01-18 浏览次数:  166 下载次数:  1
问题描述
MSTP环境的时候发现S3700设备优先级别是默认的32768,但是计算的结果是自己为根
告警信息

处理过程
交换机组网MSTP配置需要达到的效果

 1、根选举是否正常

<B08-B-S3700-1>dis stp inst 0

-------[CIST Global Info][Mode MSTP]-------

CISTBridge         :0.000f-e218-d10c

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

CIST Root/ERPC      :0.000f-e218-d10c / 0

CIST RegRoot/IRPC   :0.000f-e218-d10c / 0

CIST RootPortId     :0.0

BPDU-Protection     :disabled

TC-Protection       :enabled / Threshold=6

Bridge Config

Digest Snooping     :disabled

CIST Root Type      :PRIMARY root

TC or TCN received :89170

Time since last TC :0 days 0h:57m:19s

 

<B08-B-S3700-2>dis stp ins 0

-------[CIST Global Info][Mode MSTP]-------

CISTBridge         :4096.000f-e218-cf81

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

CIST Root/ERPC      :0.000f-e218-d10c / 180

CIST RegRoot/IRPC   :4096.000f-e218-cf81 / 0

CIST RootPortId     :128.97

BPDU-Protection     :disabled

TC-Protection       :enabled / Threshold=6

Bridge Config

Digest Snooping     :disabled

CIST Root Type      :SECONDARY root

TC or TCN received :151059

Time since last TC :0 days 0h:12m:21s

 

<S3700-1>dis stp ins 0

-------[CIST Global Info][Mode MSTP]-------

CISTBridge         :32768.781d-ba80-2e68

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

CIST Root/ERPC      :32768.781d-ba80-2e68 / 0

CIST RegRoot/IRPC   :32768.781d-ba80-2e68 / 0

CIST RootPortId     :0.0

BPDU-Protection     :disabled

TC or TCN received :0

TC count per hello :0

STP Converge Mode   :Normal

Time since last TC :3 days 23h:45m:19s

 

发现问题了,这里的5700优先级别是默认的32768,但是计算的结果是自己为根。

 

<S3700-2>dis stp ins 0        

-------[CIST Global Info][Mode MSTP]-------

CIST Bridge         :32768.781d-ba80-2e7f

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

CIST Root/ERPC      :0 .000f-e218-d10c / 200179

CIST RegRoot/IRPC   :32768.781d-ba80-2e7f / 0

CIST RootPortId     :128.48

BPDU-Protection     :disabled

TC or TCN received :115

TC count per hello :0

STP Converge Mode   :Normal

Time since last TC :0 days 0h:42m:30s

 

2MSTP区域配置是否正常,都是默认配置,单个交换机独立为一个区域。

<B08-B-S3700-1>dis stp reg

 Oper configuration

   Format selector    :0

  Region name        :000fe218d10c

   Revision level     :0

   Instance   Vlans Mapped

      0       1 to 899, 905 to 909, 911 to 918, 920 to 924, 926 to 936, 938 to

              939, 951 to 954, 957 to 4094

      1       900 to 904, 910, 919, 925, 937, 940 to 946, 948 to 949, 955 to

              956

      2       947, 950

<B08-B-S3700-2>dis stp reg

 Oper configuration

   Format selector    :0

   Region name        :000fe218cf81

   Revision level     :0

   Instance   Vlans Mapped

      0       1 to 899, 905 to 909, 911 to 918, 920 to 924, 926 to 939, 951 to

              954, 957 to 4094

      1       900 to 904, 910, 919, 925, 940 to 946, 948 to 949, 955 to 956

      2       947, 950

 

<S3700-1>dis stp reg

 Oper configuration

   Format selector    :0            

   Region name        :781dba802e68            

   Revision level     :0

   Instance   Vlans Mapped

      0       1 to 949, 951 to 4094

      2       950

 

<S3700-2>dis stp reg

 Oper configuration

   Format selector    :0            

   Region name        :781dba802e7f            

   Revision level     :0

   Instance   Vlans Mapped

      0       1 to 949, 951 to 4094

      2       950

 

3MSTP端口角色和转发状态是否正常

<B08-B-S3700-1>dis stp br

 MSTID      Port                  Role STP State     Protection

   0        Ethernet2/0/1         DESI FORWARDING      NONE

   0        Ethernet2/0/26        DESI FORWARDING      NONE

   1        Ethernet2/0/1         DESI FORWARDING      NONE

   1        Ethernet2/0/26        DESI FORWARDING      NONE

   2        Ethernet2/0/1         DESI FORWARDING      NONE

   2        Ethernet2/0/26        DESI FORWARDING      NONE

 

<B08-B-S3700-2>dis stp br

 MSTID      Port                  Role STP State     Protection

   0        Ethernet2/0/1         ROOT FORWARDING      NONE

   0        Ethernet2/0/26        DESI FORWARDING      NONE

   1        Ethernet2/0/1         MAST FORWARDING      NONE

   1        Ethernet2/0/26        DESI FORWARDING      NONE

   2        Ethernet2/0/1         MAST FORWARDING      NONE

   2        Ethernet2/0/26        DESI FORWARDING      NONE

 

<S3700-1>dis stp br

 MSTID Port                        Role STP State     Protection

   0    Ethernet0/0/47              DESI FORWARDING      NONE

   0    Ethernet0/0/48              DESI FORWARDING      NONE

   2    Ethernet0/0/47              DESI FORWARDING      NONE

   2    Ethernet0/0/48              DESI FORWARDING      NONE

 

57001认为自己为根,所有端口均为指定端口,是不正常的。

 

<S3700-2>dis stp br

 MSTID Port                        Role STP State     Protection

   0    Ethernet0/0/47              DESI DISCARDING      NONE

   0    Ethernet0/0/48              ROOT FORWARDING      NONE

   2    Ethernet0/0/47              DESI DISCARDING      NONE

   2    Ethernet0/0/48              MAST FORWARDING      NONE

根因
MSTP的区域配置都是默认的配置(交换机主控板MAC地址),这样每个交换机都是独自一个区域,导致MSTP的多个MSTI实例的运算是无意义的(因为MSTI只在区域内运算),整个交换区域的MSTP树实质已经变成了CST公共生成树,区域内的生成树IST只有这台交换机自身,整个交换组网CIST实际已经变成了区域之间的CST域(instance 0)加上设备本身,导致新配置的instance实质还是和默认的instance 0 一起STP运算,无法独立控制。
解决方案
[S3700-1]上修改上行链路instance 2STP cost值,让实例2VLAN走另外一边的交换机
建议与总结
需要对区域内的VLAN做独立调整,就需要预先划定MSTP区域,并保证区域配置4要素(dis stp reg输出)的一致性。这样才能实现区域内不同的MSTI的不同选路控制。

 

[S3700-1]dis stp br

 MSTID Port                        Role STP State     Protection

   0    Ethernet0/0/47              ROOT FORWARDING      NONE

   0    Ethernet0/0/48              ALTE DISCARDING      NONE

   2    Ethernet0/0/47              ROOT FORWARDING      NONE

   2    Ethernet0/0/48              ALTE DISCARDING      NONE

  

修改上行链路instance 2STP cost值,让实例2VLAN走另外一边的交换机。

 [S3700-1]dis stp br

 MSTID Port                        Role STP State     Protection

   0    Ethernet0/0/47              ROOT FORWARDING      NONE

   0    Ethernet0/0/48              ALTE DISCARDING      NONE

   2    Ethernet0/0/47              ALTE DISCARDING      NONE

   2    Ethernet0/0/48              ROOT FORWARDING      NONE

END