[c-nsp] 2651xm performance experience

[christopher.a.kane at jpmchase.com]

> 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.

have you tried to analyze the output of a sh proc cpu or maybe sh proc 
mem?


> 
> 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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