[nsp] Cisco 2500 Traffic Limit and high cpu utilization.

[Mehmet Ali Suzen]

Dear List,
I would like to address the recent issue again. (I was a way for a week or so.)
Last IoS upgrade has been done last summer. So it might be the case.
Here is a specific real time example When CPU usage is as follows;
router1#show proc cpu | include CPU
CPU utilization for five seconds: 81%/39%; one minute: 77%; five minutes: 79%
router1#show proc cpu | include IP Input
  21   362809868  30390192      11938 28.04% 26.10% 25.32%   0 IP Input

At that point traffic on the ethernet :
 Queueing strategy: random early detection(RED)
  5 minute input rate 424000 bits/sec, 249 packets/sec
  5 minute output rate 923000 bits/sec, 223 packets/sec
And traffic on the serial interface 
Queueing strategy: random early detection(RED)
  5 minute input rate 703000 bits/sec, 127 packets/sec
  5 minute output rate 138000 bits/sec, 107 packets/sec

Serial has a HDSL connection of 1 Mb/s bandwith total.  We have
a LAN and dialup connections. At this point network slows down even
tho we didn't fullfill the bandwitdh. 

Any comment or suggestion to pin point the problem would be a help
indeed.

Best Regards,
Mehmet




On Mon, Mar 08, 2004 at 08:43:39PM -0600, Terry Baranski wrote:
> As Justin mentioned, the CEF problems you had were probably the result
> of bugs, as any traffic that can't be CEF switched for whatever reason
> is normally just punted down to the next switching path (e.g., fast
> switching) rather than dropped or anything of that nature.  So an IOS
> upgrade may be in order.  
> 
> That being said, what is the bandwidth of the serial interface and
> approximately how much traffic do you think is going through the router
> when the CPU usage gets high?  And how high does the CPU usage get?  If
> most of the current traffic is being fast switched (it should be;
> confirm with "show interface switching"), CEF may not even make that big
> of a difference. (You can't know for sure until you try it, but it would
> be wise to keep in mind that CEF isn't a definite fix here.)  I
> mentioned performance-reducing features earlier and you have a good
> number of them enabled.  You may simply be approaching the limit of what
> a 2500 can handle under such a configuration.
> 
> -Terry
> 
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