[98127] in North American Network Operators' Group
Re: Problems getting Cisco router and Motorola Nextlevel system to work together
daemon@ATHENA.MIT.EDU (Rodney Dunn)
Wed Jul 25 00:46:45 2007
Date: Tue, 24 Jul 2007 22:58:24 -0400
From: Rodney Dunn <rodunn@cisco.com>
To: michael.dillon@bt.com
Cc: nanog@merit.edu
In-Reply-To: <D03E4899F2FB3D4C8464E8C76B3B68B0BF8BB1@E03MVC4-UKBR.domain1.systemhost.net>
Errors-To: owner-nanog@merit.edu
We should probably move this over to cisco-nsp.
I'd be interested to see a 'sh buffers' because if it's
process switching that much data I bet the buffers are thrashing.
I seem to remember working on something very similar to that
4 or 5 years ago when a customer has brigding over a bunch of
ATM PVC's and they told me it was some type of IPTV set top box.
We tuned the buffers really high so they didn't trim back and
it worked.
We also do some bridging under interrupt without process
switching too last time I checked so some more data would
be helpful.
Move it over to cisco-nsp@puck.nether.net and we can help
more on the Cisco side if you want.
Rodney
On Tue, Jul 24, 2007 at 09:25:49PM +0100, michael.dillon@bt.com wrote:
>
> > The router is currently configured to use IRB which is a
> > hybrid process.
> > The problems is that the IRB process is overloaded and is
> > dropping traffic faster than it can process it.
>
> Which NPE is in this router?
>
> Basically, the 7200 has underpowered CPUs and if you force it to process
> switch, then it handles a LOT LESS packets per second than you might
> think. I expect that your config is forcing process switching rather
> than fast switching.
>
> The only three solutions are
>
> A) run less traffic through the 7200 so that process switching can cope
>
> B) stop using the feature that forces process switching
>
> C) replace the 7200 with a 7300 which will probably not have CPU issues.
> However, not knowing the specifics of what IRB is doing, I would advise
> you to test a replacement platform before committing to it.
>
> Oh well, maybe 4 solutions. If you are using a weak NPE such as NPE-200
> you may be able to get some joy by upgrading to a more powerful one. For
> instance an NPE-400 should handle roughly twice the load of an NPE-200.
>
> --Michael Dillon
