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New Member

IP accounting killing my 3640

I have a 3640 running IP over Ethernet & BRI.

The load (show proc) runs anywhere from 4 - 14 %.

When I enable IP accounting the load jumps to 100%

The router is so busy I cannot do any analysis as I have to remove IP accounting to allow my userts to work.

I have 4 ethernet ports 3 internal 1 extrnal to the Internet, I leave ip accounting

switched on the internal ports No Problem.

As soon as I enable the port to the Internet the load jumps to 100 %.

Any ideas would be welcome


Re: IP accounting killing my 3640

what is the size of the pipe & what is the load when you enable ip accounting ? did you try to enable it just on the wan link ?

What is the process that is eating up the cycles on your CPU ?

New Member

Re: IP accounting killing my 3640

Hi the pipe is a 10 mb 1/2 duplex.

The load before enabling ip accounting on the router is between 3 - 15 %.

As soon as ip accounting is enabled the load jumps to 100 %.

(even if it is only 3% when we start)

Yes I have tried just the WAN connection with exactly the same results.

As for the process that is running.....I am not sure. I will have to test this again during the night when it won't effect my users to much.

I assume I should run "show proc" & look for the culprit??

New Member

Re: IP accounting killing my 3640

OK; So I did some testing over the weekend.

I could NOT find any process consuming all the cycles.

However when I "Shutdown" my BRI ports the problem disapeared.

I am running 12.0(7T) on this router

Basic Rate ISDN software, Version 1.1.

6 Ethernet/IEEE 802.3 interface(s)

1 Serial network interface(s)

8 ISDN Basic Rate interface(s)

Integrated NT1's for 8 ISDN Basic Rate interfaces

DRAM configuration is 64 bits wide with parity disabled.

125K bytes of non-volatile configuration memory.

8192K bytes of processor board System flash (Read/Write)


Any other Ideas ????

Cisco Employee

Re: IP accounting killing my 3640

IP accounting is a cpu intensive as ios has to calculate umber of bytes and packets switched through the Cisco IOS software on a source and destination IP address basis.

We need to see output of "sh proc cpu" to see which process is spiking the cpu. Cpu may be spiking because of interrupts. Here is the url for troubleshooting that.

New Member

Re: IP accounting killing my 3640

Also, doesnt IP Accounting turn off CEF?

I may be wrong here, but Im pretty sure it does, so youll be back to process switching everything.

You may be better of looking at Netflow, as that does work with CEF.