Rancid crashing routers/remove commands

Roderick B. Greening Roderick.Greening at bell.ca
Fri Dec 30 13:32:46 UTC 2005

If it's a Cisco router (like a Cat 5500 RSM) it's possible that the router
could be crashing upon multiple executions of "sh running" and "write term".

There is a memory issue in certain IOS's that when examining the running
memory config causes a memory leak.

I have personally watched this happen via a SNMP poll to my RSM. The memory
will leak over a few hours or sometimes days, and then start having
problems. This is a bug with the Cisco IOS. I would expect that same with
whatever hardware/software you are using. It's not really a RANCID problem
as such.

However, one possible work around would be to not have RANCID execute a "sh
running" or "write term", and instead use "sh start" or "sh config". The
only issue doing this is that you do not capture any changes if they haven't
been written to memory (via "write memory" or "copy running start"). Of
course, you could write a rule/patch to detect the RSM, and if it is issue a
"write mem" first and then do a "sh config". This gets around the memory
leak issue. Although, now this forces the change to be committed to memory,
and perhaps it shouldn't, at the time RANCID is polling.

Anyway, some food for thought.

-----Original Message-----
From: owner-rancid-discuss at shrubbery.net
[mailto:owner-rancid-discuss at shrubbery.net] On Behalf Of Austin Schutz
Sent: Friday, December 30, 2005 5:57 AM
To: Andrew Partan
Cc: Austin Schutz; rancid-discuss at shrubbery.net
Subject: Re: Rancid crashing routers/remove commands

On Thu, Dec 29, 2005 at 03:48:36PM -0500, Andrew Partan wrote:
> On Thu, Dec 29, 2005 at 12:38:28PM -0800, Austin Schutz wrote:
> > 	We've had problems here which the vendor "suspects" is due to
> > rancid rapid firing off commands during polling.
> What vendor is feeding you that line of bull?

	Well the bull is second hand from one of our engineers, so I'll skip
the public flogging for now.
	It sounds pretty far fetched to me as well, but I'm not part of the
team responsible for maintaining these albatrosses - excepting the rancid
polling. It's far easier in my case to just add the kludge rather than try
prove the polling isn't causing side effects.


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