[c-nsp] 2651xm performance experience

[Ian MacKinnon]

hi Barney
I have seen high CPU on 2651XM before, and after a lot of
troubleshooting with TAC, the best we could find was that it was due to
IP Process interupts.
This seemed to be due to the FE port being in promiscuous mode.
this meant EVERY packet on the lan caused an interrupt.
Eventually we moved to 2800's instead.

Have you tried following the high cpu troubleshooting guide,
http://www.cisco.com/warp/public/63/highcpu.html

Ian


barney gumbo wrote:
> I have a pair of 2651xm which are running high CPU at ~10 min intervals. The
> CPU runs up to about 90% for ~90 seconds then recovers.  The bandwidth being
> consumed when this happens is less then 700 kbps total through the router.
> I believe the 2651xm is rated at 20 mbps, when there are no fancy
> configurations/features etc.  Both routers are currently running 12.4 latest
> releast, base IP image.
> 
> I know the traffic flow which occurs when the CPU runs up, and that flow is
> normal expected traffic, as noted only consuming ~700 kbps.  The 2651xm have
> performed well for me in the past as a simple LAN router, routing between
> two fast-e networks, and we definitely got alot more then 700kbps, typically
> around 15 Mbps, w/o any issues.
> 
> Each 2651xm is configured with 4 pt-pt T1 links and a single fast-e link to
> a LAN.  The routing protocol is EIGRP.  There is a QOS policy which matches
> some VOIP traffic and assigns it to a priority queue which reserves 50% of
> the interface bandwidth, everythig else is fair-queue.  There are no special
> features enabled on the router, no NAT, no interface access-groups, no
> policy-routing, very simple configuration.
> 
> I've tried using MLPP for the 4x T1 and I've also tried this with each T1
> being in it's own /30.  In both scenarios, traffic is being balanced well
> across the T1's in both directions.  High CPU happens with MLPP or each T1
> having it's own /30.  Each T1 is performing fairly well, other then slightly
> high latency (no jitter however) they take the same physical transport path.
> 
> As best as I can tell, the router isn't doing any IP fragmentation or
> generating/processing alot of ICMP traffic.  IP Cef is enabled.
> 
> I've tried downgrading to 12.3 latest release, same CPU consumption.
> 
> Can anyone provide any insight to why this might be happening?
> Any suggestions on how to troubleshoot this further?
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