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Cisco Problems switch Loop guard blocking and flapping between port

bartosz.wrzosek
Level 1
Level 1

‎12-01-2021 02:26 AM

Hello I have problem with loop guard and flapping port.
Short info about my network .
I have 44 switch connect in spanning tree MSTP.
  I was configure 3 instances .
I deleted the ip switch addresses and changed the vlan names. Vlan X is from instance 1 and Vlan Y is from instance Y

When I change Vlan in instance 3 (adding new Vlan) have this info

My question is:

why if I change something in the  instanceMST3,  something changes is MST1 and Vlany from the MST1 flapping port between switches?

 

 

10:36:15Local7Critical 1851: .Dec 1 10:38:05.857: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet1/1 on MST1.
10:35:35Local7Warning 1713: .Dec 1 10:37:25.331: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f733.17fe in vlan X is flapping between port Gi1/26 and port Gi1/25
10:35:35Local7Warning 998: .Dec 1 10:37:25.342: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f733.17fe in vlan X is flapping between port Gi1/2 and port Gi1/1
10:35:35Local7Warning 1698: .Dec 1 10:37:25.338: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f733.17fe in vlan X is flapping between port Gi1/26 and port Gi1/25
10:35:35Local7Warning 1678: .Dec 1 10:37:25.337: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f733.17fe in vlan X is flapping between port Gi1/26 and port Gi1/24
10:35:35Local7Warning 1838: .Dec 1 10:37:25.401: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.a54c in vlan X is flapping between port Gi1/27 and port Gi1/25
10:35:35Local7Warning 1850: .Dec 1 10:37:25.365: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.a54c in vlan X is flapping between port Gi1/2 and port Gi1/1
10:35:35Local7Warning 1837: .Dec 1 10:37:25.317: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f733.17fe in vlan X is flapping between port Gi1/25 and port Gi1/27
10:35:35Local7Warning 1836: .Dec 1 10:37:25.275: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.b12e in vlan X is flapping between port Gi1/25 and port Gi1/27
10:35:35Local7Warning 1849: .Dec 1 10:37:25.331: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f733.17fe in vlan X is flapping between port Gi1/2 and port Gi1/1
10:35:35Local7Warning 1848: .Dec 1 10:37:25.264: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.b12e in vlan X is flapping between port Gi1/2 and port Gi1/1
10:35:35Local7Warning 1979: .Dec 1 10:37:25.407: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.a54c in vlan X is flapping between port Gi1/26 and port Gi1/27
10:35:35Local7Warning 1978: .Dec 1 10:37:25.250: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.b12e in vlan X is flapping between port Gi1/26 and port Gi1/27
10:35:35Local7Warning 1977: .Dec 1 10:37:25.250: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f733.17fe in vlan X is flapping between port Gi1/27 and port Gi1/26
10:35:35Local7Warning 1873: .Dec 1 10:37:25.326: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f733.17fe in vlan X is flapping between port Gi1/2 and port Gi1/3
10:35:35Local7Warning 1872: .Dec 1 10:37:25.291: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.a54c in vlan X is flapping between port Gi1/2 and port Gi1/3
10:35:35Local7Warning 1745: .Dec 1 10:37:25.351: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.a54c in vlan X is flapping between port Gi1/2 and port Gi1/1
10:35:35Local7Warning 1744: .Dec 1 10:37:25.317: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f733.17fe in vlan X is flapping between port Gi1/2 and port Gi1/1
10:35:35Local7Warning 1871: .Dec 1 10:37:25.256: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.b12e in vlan X is flapping between port Gi1/3 and port Gi1/2
10:35:35Local7Warning 1743: .Dec 1 10:37:25.250: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.b12e in vlan X is flapping between port Gi1/2 and port Gi1/1
10:35:35Local7Warning 1734: .Dec 1 10:37:25.378: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.a54c in vlan X is flapping between port Gi1/2 and port Gi1/1
10:35:35Local7Warning 1733: .Dec 1 10:37:25.277: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f733.17fe in vlan X is flapping between port Gi1/2 and port Gi1/1
10:35:35Local7Warning 1732: .Dec 1 10:37:25.244: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.b12e in vlan X is flapping between port Gi1/1 and port Gi1/2
10:35:35Local7Warning 2429: .Dec 1 10:37:25.370: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.a54c in vlan X is flapping between port Gi1/3 and port Gi1/1
10:35:35Local7Warning 2428: .Dec 1 10:37:25.324: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f733.17fe in vlan X is flapping between port Gi1/3 and port Gi1/1
10:35:35Local7Warning 2427: .Dec 1 10:37:25.178: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.b12e in vlan X is flapping between port Gi1/3 and port Fa1/12
10:35:35Local7Warning 1724: .Dec 1 10:37:25.403: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.a54c in vlan X is flapping between port Gi1/1 and port Gi1/2
10:35:35Local7Warning 1723: .Dec 1 10:37:25.370: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f733.17fe in vlan X is flapping between port Gi1/1 and port Gi1/2
10:35:35Local7Warning 1722: .Dec 1 10:37:25.269: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.b12e in vlan X is flapping between port Gi1/1 and port Gi1/2
10:35:15Local7Warning 1080: .Dec 1 10:37:05.745: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.a54c in vlan X is flapping between port Gi1/2 and port Gi1/1
10:35:15Local7Warning 1079: .Dec 1 10:37:05.678: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.b12e in vlan X is flapping between port Gi1/1 and port Gi1/2
10:35:15Local7Warning 1078: .Dec 1 10:37:05.511: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f733.17fe in vlan X is flapping between port Gi1/1 and port Gi1/2
10:35:14Local7Warning 2404: .Dec 1 10:37:04.691: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f713.b12e in vlan X is flapping between port Gi1/27 and port Gi1/25
10:35:14Local7Warning 2403: .Dec 1 10:37:04.621: %SW_MATM-4-MACFLAP_NOTIF: Host 000a.f733.17fe in vlan X is flapping between port Gi1/27 and port Gi1/25
10:35:13Local7Warning 1832: .Dec 1 10:36:56.515: %SW_MATM-4-MACFLAP_NOTIF: Host 0010.189e.3684 in vlan  Y is flapping between port Gi1/26 and port Gi1/28
10:35:13Local7Warning 1830: .Dec 1 10:36:51.223: %SW_MATM-4-MACFLAP_NOTIF: Host 000e.c6cd.bfc7 in vlan  Y is flapping between port Gi1/26 and port Gi1/28
10:35:11Local7Warning 1670: .Dec 1 10:37:01.380: %SW_MATM-4-MACFLAP_NOTIF: Host 0010.189e.3684 in vlan  Y is flapping between port Gi1/2 and port Gi1/1
10:35:06Local7Warning 2402: .Dec 1 10:36:56.525: %SW_MATM-4-MACFLAP_NOTIF: Host 0010.189e.3684 in vlan  Y is flapping between port Gi1/26 and port Gi1/27
10:35:06Local7Warning 1669: .Dec 1 10:36:56.591: %SW_MATM-4-MACFLAP_NOTIF: Host 0010.189e.3684 in vlan  Y is flapping between port Gi1/1 and port Gi1/2
10:35:06Local7Warning 1658: .Dec 1 10:36:56.599: %SW_MATM-4-MACFLAP_NOTIF: Host 0010.189e.3684 in vlan  Y is flapping between port Gi1/2 and port Gi1/1
10:35:06Local7Warning 1669: .Dec 1 10:36:56.414: %SW_MATM-4-MACFLAP_NOTIF: Host 0010.189e.3684 in vlan  Y is flapping between port Gi1/2 and port Gi1/1
10:35:06Local7Warning 1666: .Dec 1 10:36:56.527: %SW_MATM-4-MACFLAP_NOTIF: Host 0010.189e.3684 in vlan  Y is flapping between port Gi1/1 and port Gi1/2
10:35:06Local7Warning 1640: .Dec 1 10:36:56.495: %SW_MATM-4-MACFLAP_NOTIF: Host 0010.189e.3684 in vlan  Y is flapping between port Gi1/2 and port Gi1/1
10:35:06Local7Warning 960: .Dec 1 10:36:56.461: %SW_MATM-4-MACFLAP_NOTIF: Host 0010.189e.3684 in vlan  Y is flapping between port Gi1/2 and port Gi1/1
10:35:04Local7Warning 1077: .Dec 1 10:36:54.236: %SW_MATM-4-MACFLAP_NOTIF: Host 0010.189e.3684 in vlan  Y is flapping between port Gi1/2 and port Gi1/1
10:35:01Local7Warning 2401: .Dec 1 10:36:51.230: %SW_MATM-4-MACFLAP_NOTIF: Host 0010.189e.3684 in vlan  Y is flapping between port Gi1/26 and port Gi1/27
10:35:01Local7Warning 2400: .Dec 1 10:36:51.094: %SW_MATM-4-MACFLAP_NOTIF: Host 000e.c6cd.bfc7 in vlan  Y is flapping between port Gi1/26 and port Gi1/27
10:35:00Local7Warning 1072: .Dec 1 10:36:51.082: %SW_MATM-4-MACFLAP_NOTIF: Host 000e.c6cd.bfc7 in vlan  Y is flapping between port Gi1/2 and port Gi1/1
10:35:00Local7Warning 955: .Dec 1 10:36:51.033: %SW_MATM-4-MACFLAP_NOTIF: Host 000e.c6cd.bfc7 in vlan  Y is flapping between port Gi1/2 and port Gi1/1
10:35:00Local7Warning 1640: .Dec 1 10:36:51.094: %SW_MATM-4-MACFLAP_NOTIF: Host 000e.c6cd.bfc7 in vlan  Y is flapping between port Gi1/2 and port Gi1/1

BR

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7 Replies 7

paul driver
VIP
VIP

‎12-01-2021 02:40 AM - edited ‎12-01-2021 02:42 AM

Hello

@bartosz.wrzosek wrote:

My question is:

why if I change something in the  instanceMST3,  something changes is MST1 and Vlany from the MST1 flapping port between switches?

Absolutely it would as you can see from your logging, you cannot just prune vlans in an mst instance, In MST, STP is running per instance not per vlan, so the changes you make need to be made throughout your estate, not just on one particular switch and instance on that switch.

 


Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

bartosz.wrzosek
Level 1
Level 1
In response to paul driver

‎12-01-2021 03:52 AM

I don't think we understood each other. I change configurations on all switches. And during this change process, I get these logs.
For me it is strange that I change the configuration of instance 3 and in the logs I have info that something has changed in instance 1.

 

paul driver
VIP
VIP
In response to bartosz.wrzosek

‎12-01-2021 01:05 PM

Hello

 

@bartosz.wrzosek wrote:

For me it is strange that I change the configuration of instance 3 and in the logs I have info that something has changed in instance 1.

I would expect to see some stp disruption because those mst instances (1,2,3) would not have parity with each other on the trunks interconnects at the time of your changes.


Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

bartosz.wrzosek
Level 1
Level 1
In response to paul driver

‎12-01-2021 10:38 PM - edited ‎12-05-2021 10:28 PM

Could you please develop your thought Why is there no parity? More details

I don't understand why the odd number of instances affects this error

BR

0 Helpful

MHM Cisco World
VIP
VIP

‎12-01-2021 04:05 AM

follow

0 Helpful

MHM Cisco World
VIP
VIP

‎12-08-2021 03:55 PM

https://www.youtube.com/watch?v=q-cNoq50Kxo

min 25, the expert talk about the add of VLAN and it effect on MST.
please watch video and I hope it help you why you get TCN for add one VLAN.

bartosz.wrzosek
Level 1
Level 1
In response to MHM Cisco World

‎12-08-2021 10:55 PM

Hello 

"min 25, the expert talk about the add of VLAN and it effect on MST."

I understand that you are suggesting that  must be 25 instances? Did I understand you well?
Thanks for the video, I am analyzing them, I will let you know when I have more questions.

BR

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