Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements
Webcast-Catalyst9k
New Member

High count of TCN changes

Hi,

 

We are facing some high count of tcn changes

 


 VLAN02312 is executing the rstp compatible Spanning Tree protocol
  Number of topology changes 1895 last change occurred 4d20h ago
          from GigabitEthernet5/5

 

Gi8./5 is access switch, Pls confirm what are the things needs to be checked to minimize the tcn changes & relevant documentation

 

br/

6 REPLIES
Super Bronze

DisclaimerThe Author of this

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Do you use portfast on your edge ports?

New Member

Hi, We have already

Hi,

 

We have already configured below in Access Port

 

 spanning-tree portfast
 spanning-tree bpduguard enable

 

Still tcn count is very high across Network, Pls suggest further how to reduce the same

 

Br/

HelloUnnecessary TCNs can

Hello

Unnecessary TCNs can also be caused by  ports running in half duplex mode -stp requires point-to-point links to be running full duplex

 

in rstp these port will negotiate as shared ports

 

sh interface status

sh spanning-tree | in Sha  (rstp only)

sh spanning-tree vlan xxx | in  Number

 

Res

Paul

 

Please don't forget to rate any posts that have been helpful. Thanks.
New Member

Hi, We are using RSTP only,

Hi,

 

We are using RSTP only, But pls give details of this command/suggestion.

 

sh spanning-tree | in Sha (rstp only) : Presently no output is showing on switches , Is this expected behaviour

 

in rstp these port will negotiate as shared ports : How to check that port is shared or not ?

 

Br/

Cisco Employee

Hi Subhojit,Could you let us

Hi Subhojit,

Could you let us know what is the end device connected to Gig8/5? Could you configure the command spanning-tree portfast edge on Gi5/5, if the end device connected to it is a work station?

 

Thanks,

Arun

 

New Member

Hi, Output shared earlier is

Hi,

 

Output shared earlier is from Core Switch, 8/5 port is access switch & in the access-switch all host port are configured with below command

 

spanning-tree portfast
spanning-tree bpduguard enable

 

Pls suggest further

 

Br/

264
Views
0
Helpful
6
Replies
CreatePlease to create content