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spanning tree topology change every few hours

  • 15 August 2016
  • 3 replies

i,ve got a problem.
1. There are ten Enterasys switches 1x S4 (Core) 9x C5k

We are using MSTP with only one instance (0)
All switches are conectet directly to the S4, but two of them are also connectet to each other for reduncy reasons.
STP Priority S4 = 0 first C5k in the trinangle = 4096 second in triangle = 8192 and the Rest 32768

The problem the topology is changing almost ervery two hours on some of the switches not everywhere. But Root bridge included. I've got a change count of <150000 this is running for year now.

Any Ideas? what do need an information for helping me?

Sorry for bad englisch (from Germany)

3 replies

Userlevel 1
Apart from the 10 Extreme switches you mentioned, are there any other switches participating in the STP domain?
If you have not already done so, consider configuring the STP "Spanguard" feature and configure all edge ports as "adminedge true"
See the following article for more information:-

Thanks for your Reply,
No there no other Switches on the net now. I've tried your edge advise but no change. Next step would be using the Spanguard feature but next month we are going the change the main switches against HP Components with a special technican for this. So no more need to work on an error that has existed for years and no one has noticed.
Userlevel 4

Here are some articles you can read that may shed some light on this issue:
How to troubleshoot spanning tree topology changes on SecureStack, N-Series and S-Series

SpanningTree Topology Changes Seen From Downstream Device

S-Series showing a lot of topology changes in the Netsight

If you need more assistance give us a call at the GTAC