My customer has a 2950G switch running IOS 12.1(9), the problem was that when some PC's are rebooted, the ports are in down state, at first, I thought that it might be a problem of duplex mismatch or speed, when I connected the console cable to the switch, it was responding very slowly (it took me 16 min to go to the enable mode), it seemed that the switch utilization is extremely high, I could not even see the output of the "show process ..." commands after 30 minutes of issueing the commands, it seems that the switch is very busy to move the blocking ports to the forwarding state of STP as well as from sending console messages.
When I rebooted the switch, everything came back normal, the output of the show interface command does not show anything weird, I tried to trace any process that might be causing alot of utilization, but still eveything seems normal!! This happens from time to time
Try enabling port fast on the ports that have the PC connected to them. This would move the ports to forwarding state, without going through the blocking, listening, or learning states. Also check the configuration for duplex mismatches. it generally happens if one end is configured for full duplex while the other is in auto. Here's a nice doc on troubleshooting NIC compatibilty issues. Hope this helps. http://www.cisco.com/warp/public/473/46.html
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