Since you've already replaced the router and upgraded the IOS, my first
guess is that this is traffic related.  Perhaps you have a routing loop or
something of that nature.  Even though it might take your router down, have
you tried debug ip packet?    Seriously, this might help pinpoint the
offenders.

Another thought is to just look at devices that are generating traffic that
is being encrypted.  I know, that's obvious, but that's what I would do.  It
may not be a routing loop, per say, it may just be a crazy device generating
a lot of traffic that is hitting your crypto access lists.

Being a slightly crazy person, I'm still leaning toward doing some
debugging.  :-)  There may be some other crypto-related debugs that point
out what's happening, I'll have to check into that when I get back to work
tomorrow.

Oh, another thought.  Do a 'show crypto ipsec sa' and look for unusually
high counters.  That might also lead you to the culprit(s).

Good luck, and let us know if you find anything.

John



|  Hi all,
|  
|  Thought I'd ask if anyone has experienced similar to a problem I've had
|  recently. It's going to TAC now and I've got a workaround, but I'd be
|  interested if anyone could suggest the reason or confirm a bug which I
have
|  been unable to locate.
|  
|  These routers had been running for nearly a year with no problems. All of
a
|  sudden they started giving problems and I have been unable to track down
|  what external network changes may have triggered it. There were no config
|  changes to the two routers (We run Resource Manager Essentials which
|  monitors router config changes)
|  
|  Set-up was two 3660's running 12.1.1T, DES encryption over serial 2Mb
link.
|  The links were set up with encryption peers as the serial IP addresses
and
|  encryption access lists set up symmetrically without using any any on the
|  serial interfaces.
|  
|  After reload routers come up fine and encryption runs O.K.
|  After a varying length of time (around 5-10 minutes), the CPU utilisation
|  builds up gradually until it sits at around 98%. This utilisation was
almost
|  totally due to encryption process.
|  
|  After swapping out the router and upgrading IOS, the problem still
existed.
|  
|  I have got around the problem by using IP Unnumbered Loopback0 on Serial
|  links.  CPU utilisation now hovers around 2%.
|  
|  Anybody seen similar, or suggest what could make the CPU utilisation
|  snowball like this?
|  
|  
|  Thanks,
|  
|  Gareth Hinton
|  
|  
|  
|  
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