[afnog] Cisco 3745 configuration register 0x101

Mark Tinka mtinka at globaltransit.net
Tue Jun 9 15:21:29 UTC 2009


<copying to the list for archiving>

On Tuesday 09 June 2009 06:06:20 pm Kweheria Erick wrote:

> Hi Mark,

Hello Erick.

> Thanks for your response and willingness to assist.
> I can confirm from cvs config management that no config
> changes had been made for over a week; the reloads began
> yesterday. The router is upcountry and seldom is there
> need to change anything.

Okay.

> The IOS hasn't been upgraded in over a year.

Okay.

> Attached is the "sh logg" output.

Looking at the log file you attached, there isn't anything 
of real interest, even at the time of the reload.

Might you have a 'crashinfo' file? If so, check under 
'bootflash:' or 'flash:'.

> Yesterday the router kept reloading at approx. intervals
> of 15-30min and even after manually changing the register
> value from 0x101 to 0x2102 and saving the reloading still
> recurred with the same "unkown cause".

The router reloading itself is not necessarily determined by 
the running configuration register. The configuration 
register just decides "how", if you will, the router will 
reload when it does so - simplified.

The key issue here is that the router, for some (unknown) 
reason, reboots on its own nearly four times every hour.

Something is triggering this, and it smells of either a 
software issue, a hardware issue, or both.

As there haven't been any configuration changes that could 
be causing the reloads (not sure if they are crashes), might 
you have any reason to suspect faulty hardware, perhaps 
caused by a power surge, faulty components, e.t.c.?

> At the moment the router has been running for the last
> 19Hrs and suspecting this to be the calm before a storm I
> have already downloaded IOS:-
> c3745-spservicesk9-mz.124-25a.bin, initiated a change
> control and also configured ftp service for exception
> dumps.

Good - dumps exported via FTP at the time of reload would be 
a great way to capture more detailed crash information, 
assuming the software was defective, that could have 
otherwise been lost through a regular crash dump file 
creation on the local system.

> The router has memory capacity and it's therefore my
> intention to load the new IOS in the flash and configure
> the router to boot from the new IOS.
> Will let you know how this goes.

Okay, good luck.

Let us know how that goes.

> Meanwhile, any new ideas that could help are most welcome
> and appreciated.

Are you capturing memory and CPU utilization? If CPU 
utilization is high, you might want to find out what 
processes are contributing to this.

Try to see if you can correlate that to memory utilization. 
It might be worthwhile to poll this information and graph it 
so you can monitor it more closely.

In case you're also able to open a case with TAC, it'd help 
too.

If you can also post a 'show stacks', there might be 
something in there if the system did, indeed, crash.

Cheers,

Mark.
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