[c-nsp] 3750 High Cpu IP Input

[Chris Lane]

The 3750 doesn't support GRE from what i have read ? No NAT either, strictly
L3. This box has been in production for over a year and doesn't really do to
much as you can see from my orig thread it moves about 11MB.

This just started late last night yet we didn't add any new customer nor did
anybody even touch switch as the device is remote.

I read in an older thread regarding same thing that the person rebooted and
of course it resolved issue. I am planning to do that Early tomorrow am,
but
i really want to know what the heck is causing this.

Yes CEF is running.

Thanks to all for input.



On Thu, Apr 23, 2009 at 4:01 PM, Peter Rathlev <peter at rathlev.dk> wrote:

> 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
>
>
>


-- 
//CL