[cisco-bba] High CPU utilization on Cisco 7206VXR seems to belimiting performance of higher-speed users

[Oliver Boehmer (oboehmer)]

Frank Bulk <> wrote on Thursday, April 12, 2007 8:49 PM:

> We've had two complaints from 2 Mbps customers that they aren't
> getting their contracted bandwidth.  I went to one of them and
> confirmed that it's mixed, getting only up to 1.5 Mbps at times. 
> Half of our customers run at 128/128 kbps, another 40% at 1024/256
> kbps, and the remaining at 2048/384 kbps.
> 
> We have a Cisco 7206VXR with an NPE400 with 491520K/32768K bytes of
> memory running c7200-is-mz.122-26.bin.  The processor is running at
> about 60%, up from 40% a year ago.  I believe that the CPU has
> something do with the performance.
> 
[...]
> 
> I followed the advice on Cisco's web pages on troubleshooting IP
> Input CPU load on Friday but nothing I tried seemed to make a
> difference. 
> 
> Our DSL customers come in on two OC3's and we have some FTTH customers
> coming in on Fa0/0.  Our main Ethernet interface, Fa0/1, does have
> quite a few drops and flushes, but you can see the loads are low and
> cacti reports interface utilization of about 10 to 15 Mbps.
[...]
> A complete 'show interfaces switching' and 'show ip traffic', one
> after another, can be found zipped up in this file:
> http://www.mtcnet.net/~fbulk/show_interfaces_switching_ip_traffic.zip
> 
> I also dropped the two ACLs we have on our Ethernet interface and it
> didn't make a difference.
> 
> We have about 2013 active PPPoA connections and 35 PPPoE connections.

You are definitly switching too much traffic using process-switching.
There are several reasons for this:
- You are re-assembling on the router (not sure if any L2TP is
involved)?
- You are using per-user features which are not supported in CEF
- ...

We'd need to see the full config, more snapshots of "show int switching"
(best do a "clear counter", wait 5 mins and show the counters) and
multiple "show ip traffic" a few minutes apart to see which counter is
increasing.  A "show ip interface virtual-access <x>" of a couple of
users could also provide hints, please also show the Radius profiles.

Feel free to send unicast..

	oli