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New Member

my 3640 restart by itself,why?

Cisco Internetwork Operating System Software

IOS (tm) 3600 Software (C3640-JS-M), Version 12.1(3a)T1, RELEASE SOFTWARE (fc1)

Copyright (c) 1986-2000 by cisco Systems, Inc.

Compiled Sat 29-Jul-00 11:48 by ccai

Image text-base: 0x60008950, data-base: 0x61346000

ROM: System Bootstrap, Version 11.1(20)AA2, EARLY DEPLOYMENT RELEASE SOFTWARE (fc1)

System returned to ROM by watchdog timer expired

System restarted at 12:00:11 Beijing Sat Aug 16 2003

System image file is "flash:c3640-js-mz.121-3a.T1.bin"


  • Other Network Infrastructure Subjects
New Member

Re: my 3640 restart by itself,why?


Do have the output of "show stack" after the crash.


New Member

Re: my 3640 restart by itself,why?

yeah........ it will restart.. but in majority of the cases apart from the hardware issue........ high throttling and overloading is the one to blame upon....... in that case just try upgrading to a mainline IOS. In the show interface status specially ethernet u can get this indication of high throttling..... or otherwise if the router is having some modular cards, errors in those can also be the cause.

But the best bet is to analyse the show stack.....


Re: my 3640 restart by itself,why?

Your router restarted because of:

"System returned to ROM by watchdog timer expired".

Cisco processors have timers that guard against certain types of system hangs. The CPU periodically resets a watchdog timer. The watchdog timer basically controls the time of each process. If the timer is not reset, a trap occurs. If a process is longer than it should be, the watchdog timer is used to escape from this process.

There are two main types of watchdog timeouts.

The first type is usually caused by a software problem.

The second type of watchdog timeout is usually due to a hardware problem and is reported in one or both of these two ways:

The show version command output shows:

Router uptime is 17 minutes

System returned to ROM by watchdog timer expired

System image file is "flash:c3640-is-mz.122-3.bin"

The console logs show:

System returned to ROM by watchdog timer expired

*** Watch Dog Timeout ***

PC = 0x800001b4, SP = 0x61e19590

Both of these are potential software issues and need further investigation based on their symptoms. For troubleshooting Watchdog Timeout crashes, see: