[c-nsp] 3750 High Cpu IP Input

[Ivan Pepelnjak]

Your CPU is @ 70%, 25% of those spent in interrupt (CEF) packet switching
(the difference between 68% and 43% in the five-second figures), yet the IP
Input uses only 16%. There might be something else going on?

Ivan
 
http://www.ioshints.info/about
http://blog.ioshints.info/

> -----Original Message-----
> From: Peter Rathlev [mailto:peter at rathlev.dk] 
> Sent: Thursday, April 23, 2009 10:01 PM
> To: Chris Lane
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] 3750 High Cpu IP Input
> 
> On Thu, 2009-04-23 at 13:51 -0400, Chris Lane wrote:
> > Having a high cpu with my 3750 not in stack. sh proc cpu | exclude 
> > 0.00 CPU utilization for five seconds: 68%/43%; one minute: 
> 69%; five minutes:
> > 70%
> >  PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min 
> TTY Process
> > 168    40336940  92166921        437 15.49% 15.76% 15.97%   
> 0 IP Input
> > 
> > WS-C3750-48TS      12.2(35)SE2             C3750-ADVIPSERVICESK
> > 
> > According to some old threads this was a bug in some older 
> IOS which 
> > was fixed in 12.2(25)
> > 
> > Egress port is quiet:
> > 5 minute input rate 11171000 bits/sec, 1353 packets/sec
> >   5 minute output rate 2821000 bits/sec, 681 packets/sec
> > 
> > Sure i can upgrade IOS!
> > Looking to know WHY this box is so hot!
> 
> When you see the box spending processor time in "IP Input" 
> it's because it cannot hardware switch the traffic it moves. 
> This is (almost) always a bad thing when you're looking at a 
> L3 switch.
> 
> There can be several reasons for this. Features not supported 
> in hardware (= most features, e.g. GRE or NAT) is one 
> possible thing. TCAM starvation/overflow could also make the 
> box do software switching.
> 
> It depends on your configuration. Has it always done this?
> 
> Regards,
> Peter
> 
> 
> 
>