Have you never seen a Cisco crash?

It is not common see a Cisco crash: Software forced crash, Bus Error, Software watchdog timeout, and so on…

But if you would do it, there is a pretty trick :) : it’s the “test crash” command, an hidden IOS command. This can help you if you are lucky enough to have the real crash exactly like one of those you can test with “test crash” command.

Below, the test crash menu:

Ciscozine#test crash
WARNING: Command selections marked with '(crash router)' will crash
         router when issued. However a selection 'C' will need to
         be issued IMMEDIATELY before these selections to enable them.
Type the number for the selected crash:
 1  (crash router) Bus Error, due to invalid address access
 2  (crash router) Bus Error, due to parity error in Main memory
 3  (crash router) Bus Error, due to parity error in I/O memory
 4  (crash router) Address Error, due to fetching code from odd address
 5  (crash router) Jump to zero
 6  (crash router) Software forced crash
 7  (crash router) Illegal read of address zero
 8  (crash router) Divide by zero
 9  (crash router) Corrupt memory
 C  Enable crash router selection marked with (crash router)
 R  (crash router) User enter read bus error address
 U  (crash router) User enter write bus error address
 W  (crash router) Software watchdog timeout (*** Watch Dog Timeout ***)
 w  (crash router) Process watchdog timeout (SYS-2-WATCHDOG)
 d  Disable crashinfo collection
 e  Enable crashinfo collection
 i  Display contents of current crashinfo flash file
 m  Write crashinfo on crashinfo RAM
 n  Change crashinfo flash file name
 q  Exit crash menu
 s  Save crashinfo to current crashinfo flash file
 c  Close current crashinfo flash file
 t  Write crashinfo on console TTY
 x  Exit crash menu

To generate a Cisco crash, type “C” to enable Cisco crash feature. Then select the crash type that you would generate.

How Cisco test crash command works?

In this example, I have selected the “s” option to save crashinfo to the flash. The file will be named like: crashinfo_YYYYMMDD-hhmmss, where:

  • YYYY is the year, like 2009
  • MM is the month, like 06
  • DD is the day, like 18
  • hh are the hours, like 15
  • mm are the minutes, like 03
  • ss are the seconds, like 34

As you can see, the file saved on the flash memory (due a Software forced crash, option #6) could be read with the command “more”. Remember that it is not easy understand the crashinfo file…


  1. Hi Fabio,
    great stuff…. yes never seen cisco crash…as it’s quality stuff. yes sometimes things happen. but compared to Cisco 0 & Nortel unlimited crashes.


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