slow over router

Jul 09, 2007 6 Replies

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dt1649651 19 years ago

The router is a 2811 with 4 Port FE Switch. This switch connects local LANs together. Recently I notice that copying files between LANs is slower than usual and "show process" shows a high cpu utilization:

CPU utilization for five seconds: 99%/35%; one minute: 99%; five minutes: 90%

Below is the output of "show process" when there is no copying file running.

CPU utilization for five seconds: 28%/10%; one minute: 24%; five minutes: 29%

It was not that slow before. Any advice is greatly appreciated.

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Gabriele Beltrame 19 years ago

ha scritto nel messaggio news: snipped-for-privacy@r34g2000hsd.googlegroups.com...

Hi,

I'm in hurry so I've to be quick... it seems that your router is using much more CPU that normal (probably due to process switching during transfers or other control plane processes) ... I suggest you look in your config and see if you have CEF enabled (or at least Fast Switching).

Regards, Gabriele

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dt1649651 19 years ago

messaggionews: snipped-for-privacy@r34g2000hsd.googlegroups.com...

Thanks Babriele. I checked and there is no CEF or fastswitching set on the router.

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Gabriele Beltrame 19 years ago

Hi,

Then enable ip (ip cef in Global Config) (by default it is enabled... maybe someone has disabled it for debugging purposes)

Since it could be disabled also on a per-interface base, make sure it is enabled on all interfaces ( ip route-cache cef in Interface config )

Regards, Gabriele

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dt1649651 19 years ago

messaggionews: snipped-for-privacy@r34g2000hsd.googlegroups.com...

This router has a serious problem with IP CEF that it will crash the router under high load. Cisco techsupport suggested me to turn off CEF. I just turned it on to check if the throughput is improved. The throughput did improve but it crashed the router after about 10 seconds :(

I have to check if there is a newer IOS that fixes this problem.

Thanks, Gabriele.

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Gabriele Beltrame 19 years ago

Hi,

Disable CEF and enable Fast Switching then ( ip route-cache flow )

The first packet for each flow will be process switched, but the following ones will be served within the interrupt.

Regards, Gabriele

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dt1649651 19 years ago

messaggionews: snipped-for-privacy@n2g2000hse.googlegroups.com...

I downloaded the ios 12.4.15T and this one, according to the bug database, already fixed this CEF bug ( more exactly since 12.4.5 or

12.4.4T ). After upgrading the IOS, I can turn CEF on and now the throughput is as expected.

Thanks, Gabriele.

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