[cisco-nas] High CPU usage on IP INPUT process

[Dennis Peng]

Gert Doering [gert at greenie.muc.de] wrote:
> Hi,
> 
> On Fri, Jan 28, 2005 at 02:09:13PM +0700, Souphonh wrote:
> > I am using Cisco 3620, IOS 12.2-17 as NAT, and found that the CPU utilisation for IP INPUT is very high. I need to clear IP NAT TRANSLATION every day. Could you please suggest how can I check for the cause of high CPU utilisation.
> 
> We've recently discovered that 12.2 seems to be affected by CSCsa51150
> as well:
> 
> On a customer 1600, upgrading IOS from 12.0->12.2 made the NAT table
> virtually explode.  All entries were legitimately-looking web sessions, 
> but the translation entries just did not go away after the TCP FIN came 
> along - the bug ID above lists only 12.3(x) as affected, so we're not 
> fully sure whether it's the same bug, but it's definitely the same 
> behaviour.  

It is the same bug but we missed the commit to 12.2. I'll contact the
DE to get this done ASAP. Thanks for bringing it up.

Dennis
 
> Symptoms are similar: high CPU load, large NAT table, "clear ip nat tra *" 
> makes it go away for a few hours, then the CPU load is up again (while
> the number of NAT translation entries grows and grows and grows...).
> 
> We downgraded back to 12.0(recent), and haven't seen any NAT issues on
> that router since.
> 
> gert
> 
> 
> -- 
> USENET is *not* the non-clickable part of WWW!
>                                                            //www.muc.de/~gert/
> Gert Doering - Munich, Germany                             gert at greenie.muc.de
> fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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