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December 2020

December 2020

[Sw3850]想看STP端口状态,简单!但是硬件的呢?是否和软件同步?

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【场景重现】
 <提要> 小白是某金代的工程师,一天接了个小case,部署一个新站点;
 <方案> 一个router做GW,三个switch做二层接入;
 <问题> PC死活ping不通GW,万恶的 "....."
 <结论> 大家觉得是哪个方案更靠谱?
  A: 重配
  B: 插拔网线
  C: Reload
  D: 开case让TAC去头痛吧~
  E: 灵异事件~

【TAC结论】
  在一些特殊的情况下,STP的软件和硬件端口状态不同步,软件显示forwarding,但是实际上硬件确是block的~


【Process】
  1. Identify the MVID (VLAN TO IIF ID MAPPING)
  2. Identify the IIF-ID associated to an interface
  3. Identify the ASIC Number/ASIC Port
  4. Read the ilemststatetable(Register) to identify if they are Forwarding/Blocking





===== SPANNING_TREE STATE IN SOFTWARE: =========




======= Identify the MVID (VLAN TO IIF ID MAPPING) ========


MVID: 4


======= Identify the IIF-ID associated to an interface ========

BGL.S.09-3850-1#sh platform port-asic ifm interfaces ethernet sw 1


Interface Table 

Interface              IIF-ID                                 State                Additional Details 

Gi1/0/1                0x00c23a0000000008   READY



Gi1/0/47              0x00c19e8000000069   READY



======= Identify the ASIC Number/ASIC Port ==========



Interface Name: Gi1/0/1 

ASIC Number: 1


ASIC Port:21



BGL.S.09-3850-1#sh platform port-asic ifm iif-id 0x00c19e8000000069


Interface Table


Interface IIF-ID        : 0x00c19e8000000069 

Interface Name          : Gi1/0/47


Interface Block Pointer : 0x5666a9d0 

Interface State         : READY


Interface Stauts        : IFM-ADD-RCVD, FFM-ADD-RCVD 

Interface Ref-Cnt       : 6


Interface Epoch         : 0 

Interface Type          : ETHER


        Port Type         : SWITCH PORT 

        Port Location     : LOCAL


        Slot              : 1 

        Unit              : 47


        Slot Unit         : 47 

        SNMP IF Index     : 49


        GPN               : 47 

        EC Channel        : 0


        EC Index          : 0 

        ASIC              : 0


        ASIC Port         : 19 

        Port LE Handle    : 0x56188694


 


Non Zero Feature Ref Counts


        FID : 48(AL_FID_L2_PM), Ref Count : 1

        FID : 77(AL_FID_STATS), Ref Count : 1


        FID : 51(AL_FID_L2_MATM), Ref Count : 1


        FID : 13(AL_FID_SC), Ref Count : 1


        FID : 26(AL_FID_QOS), Ref Count : 1


 


Sub block information 

        FID : 48(AL_FID_L2_PM), Private Data &colon; 0x56684fe4


        FID : 26(AL_FID_QOS), Private Data &colon; 0x5666aab0


 


 

Gi1/0/47


========


ASIC number:0 

ASIC Port:19




======== Read the ilemststatetable(Register) to identify if they are Forwarding/Blocking =========

If MVID is 4 then use ilemststatetable-3 (Because the value  starts with 0 )

If MVID is 5 then use ilemststatetable-4




blkFwd31to0 0xffffffff --->Convert this into binary (1111 1111 1111 1111 1111 1111 1111 1111)


If the bit is set to 1 then it is blocking state


If the bit is set to 0 then it is forwarding state



ASIC Port Number 19 so check the 19th bit and it is set to 1 hence it is in blocking state                                                                                                                        


Gi1/0/1          


=======


ASIC number:1 

ASIC Port:21





blkFwd31to0 0xffcfffff --->Convert this into binary  (1111 1111 1100 1111 1111 1111 1111 1111)

 


ASIC
Port Number is 21 so check the 21st bit and it is set to 0 hence it is
in forwarding state.                                            
                                                                                      


评论
xksun725
Beginner
楼主文风真心可爱
赞分享
yinba
Cisco Employee
xksun725 发表于 2015-5-20 18:11 back.gif
楼主文风真心可爱
赞分享

谢妹子~~:lol
xupeng
Cisco Employee
谢谢楼主分享
huoran1234
Participant
那结论就是reload呗。。
Fusen Huang
Cisco Employee
郑云霞
Community Member
赞一个!不用谢!
jingjian
Advocate
假如遇到这种情况,重启后不能解决,只能交给TAC去头疼了:lol
lelwu
Cisco Employee
sxsure001
Beginner
如果遇到这等灵异事件,用户肯定会说,哎 这设备不行。。。。哈哈lollol
Lei Zhang
Cisco Employee
赞!干货好帖!!
zhengwei272
Rising star
LZ思路很好 不过不抓紧机会卖太设备不合适吧lol
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