We have a 7513 as our backbone router and pre-12.0 it was running on average at maybe
9-10% CPU. After upgrading to 12.1 and turning on CEF, that dropped to around 5%.
That's really not a good test because we were hardly pushing the thing to begin with.
Still, it does seem to make a noticable difference and we haven't had any problems
with it.
By the way, off-topic, I seem to have resolved the problems I had with excitemail, so
I've moved back to using [EMAIL PROTECTED] Lately, my email address has been changing
almost daily!
John
>
> John, Bob, Raj, Phillip and the Group,
>
> I hadn't thought of CEF much as I "thought" it wasn't available on the
> smaller routers. i.e. - only on the routers with line cards etc.
>
> However, I just enabled CEF on a 2611 and it created its table on the fly in
> no time flat. The 2611 won't do dCEF however. Also, the smaller routers
> can't do cef accounting.
>
> Anyway, now I have to mock something up in the lab to see if we can
> determine how much of any improvement CEF will give us. Since we're not
> using CEF anywhere in our network I can't just turn it on without a bit more
> research.
>
> If it only lessens the CPU load by a few percent then bigger hardware is in
> our future, but if we see gains of 20% or more then CEF would indeed be a
> cheap solution.
>
> I noticed that CEF has issues with policy routing and other features - but
> so far we're not using any of them.
>
> So, another question - does anyone have any idea/experience on how much CEF
> will gain for us? Given the average 50% load on the router - practically
> all switching load???
>
> tia
>
> Kevin Wigle
>
>
> ----- Original Message -----
> From: "John Neiberger" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Cc: <[EMAIL PROTECTED]>
> Sent: Monday, February 12, 2001 4:11 PM
> Subject: Re: Can someone interpret this please?
>
>
> > I just checked CCO and there are so many CPU-related bugs in 12.0(5) that
> I stopped counting after a while. You might want to upgrade, if feasible.
> >
> > Also, try doing a show align to see if you're getting spurious memory
> access errors. One of the bugs mentioned a high CPU usage due to these.
> >
> > HTH,
> > John
> >
> > >
> > > Bob, Phil - and the group.....
> > >
> > > Thanks for the input, gives me more to think about.
> > >
> > > Some more history..........
> > >
> > > This router is a 3620 with OC3 and FastEthernet interfaces. It has 48
> meg
> > > and is running 12.0(5)XK1.
> > >
> > > According to Cisco's docs, the 3620 should be able to handle around
> 20-40
> > > kpps.
> > >
> > > However, the router shows only around 2.6 kpps almost evenly split
> in/out.
> > >
> > > I have been unable to verify exactly on CCO but I suspect that a 3620
> cannot
> > > handle (very well) two high-speed interfaces - more specifically if one
> is
> > > OC3.
> > >
> > > I have found info where Cisco, when talking about the OC3 interface for
> the
> > > 3600 series stated:
> > >
> > > "Max two high-speed network modules in a Cisco 3640 (includes Fast
> Ethernet,
> > > ATM, HSSI)"
> > >
> > > Now the 3640 has a 100mhz processor and the 3620 has a 80 mhz processor.
> > >
> > > I'm wondering if the SAR process is overwhelming the 3620? I'm sure I
> read
> > > someplace that only one high-speed interface was recommended for the
> 3620
> > > but I haven't found that info again.
> > >
> > > Considering the low level of traffic, what else could be keeping the cpu
> > > utilization up so high? Need more info..... let me know!
> > >
> > > Kevin Wigle
> > >
> > >
> > > ----- Original Message -----
> > > From: "Phillip Heller" <[EMAIL PROTECTED]>
> > > To: "Kevin Wigle" <[EMAIL PROTECTED]>
> > > Cc: "cisco" <[EMAIL PROTECTED]>
> > > Sent: Monday, February 12, 2001 2:12 PM
> > > Subject: Re: Can someone interpret this please?
> > >
> > >
> > > > On Mon, 12 Feb 2001, Kevin Wigle wrote:
> > > >
> > > > Dear group,
> > > >
> > > > Investigating a router that is starting to loaded down. When I do
> a
> > > sh proc
> > > > cpu I get 50% or cpu utilization but the stats don't seem to add
> up to
> > > 50%.
> > > >
> > > > Is there another way to try and see where the 50% is coming from?
> > > >
> > > > sh proc cpu
> > > > CPU utilization for five seconds: 44%/44%; one minute: 50%; five
> > > minutes:
> > > > 52%
> > > >
> > > > The five second utilization numbers in the above line (44%/44%)
> represent
> > > > two things. The first number is total processor utilization and the
> > > > second is processor utilization due to interrupts. The difference in
> > > > these two numbers would be the sum of 5sec utilization by all other
> > > > processes.
> > > >
> > > > If utilization due to interrupts increases over time, it represents
> > > > traffic growth. If it jumps alot in a short amount of time, it may be
> a
> > > > DoS attack. You can verify the latter by turning on "ip route-cache
> flow"
> > > > on suspected interfaces and then looking at the output of "sh ip cache
> > > > flow".
> > > >
> > > > If the processor gets too high with legitimate traffic, you can use
> cef or
> > > > dcef (ip route-cache cef, ip cef distributed).
> > > >
> > > > Failing that, you'll probably more beefy hardware.
> > > >
> > > > Regards,
> > > >
> > > > --phil
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