[nsp] 7200 "ARP Input" CPU utilization

[Jay Stewart]

Hello,

I'm having some trouble with a 7206 that has been running pretty
flawlessly for almost a year now, no recent major config or network
changes.  Historic CPU utilization was running between 1% - 4%, but now
is bouncing between 15% and 60%, peaking at 80%, with performance
fluctuating between "OK" to "chunky".  The router in question is *NOT*
pushing much traffic, about 1.5m to 3.0m in/out through the FastEthernet
interfaces (f0/0 and f2/0) and an ATM DS3 on a PA-T3-A3+ and should not
be experiencing the performance slowdowns I'm seeing.

I've sifted http://www.cisco.com/warp/public/63/queue_drops.html#before
through my clue sponge (brain) but nothing suggested there seems to
help.

Looking at the process list suggests ARP seems to be the culprit.

CPU utilization for five seconds: 48%/3%; one minute: 48%; five minutes:
49%
  16    13493288   4354803       3098 12.53% 26.44% 25.75%   0 ARP Input
  35          32      1625         19  0.00%  0.00%  0.00%   0 ATM OAM
Input
  42     6133028  10307755        594 15.64% 15.16% 17.19%   0 IP Input

Hopefully, someone can suggest some troubleshooting steps or tips, or
maybe someone has had a similar problem that they resolved successfully
and can offer some advice.  No suggestion to simple at this point.
Thanks in advance to anyone who can help me figure this out.

Jay Stewart