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New Member

3500/2900 switches rebooting for no reason


I have lots of Cisco switches on my network rebooting for no reason. Checking the syslog I don't see any errors just before they boot but this is happening on different switchs at random times.. Any ideas why?

P.S This is happening on different OS versions (from new to old)

Cisco Employee

Re: 3500/2900 switches rebooting for no reason

What software version are you running? Can you connect a console to one of the switches and capture the stack info which will displayed on the console during reboot


Re: 3500/2900 switches rebooting for no reason

Is it possible that it's a reliable, steady power issue?

Are your switches on uninterruptible power supplies? Is it happening to any of the ones on UPSs? Is it happening to any particular switch more than once, or does it appear to be random? Is it happening by wiring closet, floor or building? Looking for any sort of a pattern or commonality here.

If you have a UPS like APC's Smart-UPS, can you connect a PC to the UPS's monitoring cable, and get it to monitor the UPS's status? That way you can log power fluctuations with their PowerChute software.

Had a customer once (school district) whose Ethernet/ATM edge switches seemed to be freezing up in some of their buildings. Manually powering the switch off and on would get it going again. None of the edge switches were on UPSs, only the server. Using PowerChute, we ultimately traced it back to brownouts in the building. People hadn't noticed them much, but the UPS did. Put the switches on UPSs, problem went away.

Hope this helps.

New Member

Re: 3500/2900 switches rebooting for no reason

Don't know if this will help, but I had a 3500 switch that kept rebooting and did not see anything is syslog. I finally hooked up a computer to the console port to see if I was missing anything. Sure enough I had a bad CPU in the switch. Not sure how many switches you are having problems with, but I would recommend not relying on syslog to help out. Hook up a computer to the console port. Hope this helps.