Topologies changes without Link changes

[agugger]

Hi

We recognize a lot of Topologies Changes between two 6509 as backbone switches and a few floor switches 4006 and 5500 without changes on the uplinks. Other floor switches run with the same release of cat OS without any bad messages. With an LAN analyzer was nothing to see. The SPT is configured to block one of the uplinks on the floor switch side. The 6509 are as root and backup root bridge defined.

Thanks

Andy

[DALE FRANCIS]

If you issue a sh spant statistic then you will be ablel to ID the device and port that those TCN's came in on, this should help break things down. If you see nothing with an analyzer then there must be nothing going on unless the analyzer is having probs with decoding STP.

The sh spantr statistc will give you all the info you should need to track this down include timestamps etc.

[donewald]

Andy,

Are you sure these Topo changes are not from access ports going into forwarding state or loosing link when a PC is powered down. Unless portfast or spanning-tree is disabled on these ports they should participate in STP and might be causing your topo changes. Here is a link on STP topochanges and the why's and how to's...

http://www.cisco.com/en/US/partner/tech/tk389/tk689/technologies_tech_note09186a0080094797.shtml

Hope this helps,

Don

[agugger]

Almost all TC are already disappear,

thanks a lot

[DWA · Accepted solution]

Have a look on this url :

http://www.cisco.com/warp/public/473/17.html

I think it will be usefull.

Like the dafrancis's recommandation.

Good luck.