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Network issues - workgroup switches crashing!

Hi All

We've been experiencing a few weird errors in the past couple of weeks - hope someone can help!

We have three 3550 EMI switches in our core, as well as a RSM router in a 5513. We got to a certain stage during the day where the CPU utilization on one of the 3550s hit 50% or more - only for about 5 minutes. Then it settles down again to its normal 3% utilization.

I have "cured" this problem by restarting the 3550 in question.

Now we have a situation where our workgroup switches (mostly 1900s, 2924s, and 2950s) get themselves in a knot. Ports will simply stop forwarding traffic, but the switch would still be manageable. Users' PCs will stop receiving traffic, until I reset the affected workgroup switch.

The only thing that changed from last year to this year, is that most of our PCs on the LAN was upgraded to Windows XP Professional. I've heard that 802.1x and the QoS service can cause problems on a Cisco network - is that true?

Any help would be appreciated.

PS: We're running IOS version 12.0(5)WC9 on the 2924 switches, version 12.1(13)EA1c on the 2950 switches, and version 12.1(13)EA1a on the 3550 switches.


Re: Network issues - workgroup switches crashing!


Could this be an issue with spanning tree?

You might be suffering from temporary loops. Please check the following to see if there is a relation:

How did you configure spanning tree?

Who is the root? Are you using portfast, uplinkfast and backbonefast correctly?

Did you alter any of the defaults for STP on some boxes?

Do all switches have the correct network diameter?