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how to trace the source of TCN from core switch to interface of access switch?

Cisco Employee
Cisco Employee

how to trace the source of TCN from core switch (Catalyst 4500 L3 Switch Version 03.06.05.E, cisco WS-C4500X-32 (MPC8572) processor (revision 9)) to interface of access switch?

Spanning tree enabled protocol mstp
Root ID Priority 0
Address 0008.e3ff.fc50
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 0 (priority 0 sys-id-ext 0)
Address 0008.e3ff.fc50
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Te1/1/2 Desg FWD 2000 128.2 P2p
Te1/1/9 Desg FWD 40000 128.9 P2p
Te1/1/13 Desg FWD 2000 128.13 P2p
Te1/1/17 Desg FWD 20000 128.17 P2p
Te2/1/2 Desg FWD 2000 128.1282 P2p
Te2/1/13 Desg FWD 2000 128.1293 P2p
Te2/1/28 Desg FWD 5000 128.1308 P2p
Po11 Desg FWD 1000 128.2571 P2p Bound(PVST)
Po12 Desg FWD 1000 128.2572 P2p
Po13 Desg FWD 20000 128.2573 P2p Bound(PVST)
Po20 Desg FWD 1000 128.2580 P2p
Po110 Desg FWD 10000 128.2670 P2p
Po161 Desg FWD 40000 128.2721 P2p Pre-STD
Po162 Desg FWD 10000 128.2722 P2p Pre-STD
Po180 Desg FWD 40000 128.2740 P2p Pre-STD
Po181 Desg FWD 60000 128.2741 P2p Pre-STD
Po250 Desg FWD 5000 128.2810 P2p



Track the Source of a TCN
In itself, a topology change notification is not a bad thing, but as a good network administrator, it is better to know their origin in order to be sure that they are not related to a real problem. Identifying the bridge that issued the topology change is not an easy task. However, it is not technically complex.
Most bridges only count the number of TCNs they have issued or received. The Catalyst 4500/4000, 5500/5000, and 6500/6000 are able to show the port and the ID of the bridge that sent the last topology change they received. Starting from the root, it is then possible to go downstream to the initiator bridge. Refer to the show spantree statisticscommand for more information.
If you have the output of a show spantree statistics command from your Cisco device, use Cisco CLI Analyzer (registered customers only) to display potential issues and fixes. To use Cisco CLI Analyzer (registered customers only), you must login as a registered customer, and have JavaScript enabled.
There is no command show spantree statistics in Catalyst 4500
cdx01as38#show spantree statistics
% Invalid input detected at '^' marker.
cdx01as38#show spann
cdx01as38#show spanning-tree statis
cdx01as38#show spanning-tree statis
cdx01as38#show spanning-tree statistics
% Invalid input detected at '^' marker.
cdx01as38#sh ver
Cisco IOS Software, IOS-XE Software, Catalyst 4500 L3 Switch  Software (cat4500e-UNIVERSALK9-M), Version 03.06.05.E RELEASE SOFTWARE (fc2)
Copyright (c) 1986-2016 by Cisco Systems, Inc.
Compiled Thu 02-Jun-16 04:02 by prod_rel_team
then i try show standby,  and use file analysis, it got error.
then i use show tech support to analysis in CLI analyzer
there is no loop or TCN keywords in result
is there another things related with TCN?
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