nanog mailing list archives

Re: Problems getting Cisco router and Motorola Nextlevel system to work together


From: Brian Raaen <braaen () zcorum com>
Date: Wed, 25 Jul 2007 07:37:23 -0400


This router has a G-1 engine with 512 DRAM.  I would stop using IRB, but it 
appears that the way that motorola has implemented pvc's is very difficult to 
work around.  The Molorola middleware is dynamically assigning the pvc.  
Yes... I have personly seen a CPE device change their vci after a period of 
time.  The device did not change ports or anything else but was provisioned 
to a different vci after just sitting there.  Thanks for the suggestions so 
far.

-- 
Brian Raaen
Network Engineer
braaen () zcorum com

On Tuesday 24 July 2007 16:25, you 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





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