[c-nsp] Increased CPU utilization on 7206VXR

[Roger Weeks]

We terminate our DSL customer connections on a 7206VXR:
IOS 12.3(11)T2
NPE-300 with 256MB RAM
PA-A3-T3 DS3 interface

We're using RBE so there is no PPPoE overhead for these connections.

Since I have been keeping CPU statistics with Cacti, from April 2005,  
our average CPU utilization grew slowly from 5% up to something just  
over 10%.  Keeping watch on the 5 minute CPU graph, our usage was  
fairly flat all through the day.

During this time we also grew from 150 DSL circuits to 500.

In early December we added two things: 60 circuits all at once, and  
in addition to our existing BGP-published /20 and /22, a third BGP- 
published Class C.

Our average CPU usage jumped from 10% to 45% immediately.  On a 5- 
minute graph, the CPU usage now peaks at 60% during the day when our  
traffic is highest, and bottoms out at 20% during the night when  
there is low traffic.

Can anyone tell me why this changed so dramatically?  I had not  
counted on 60 additional circuits causing this kind of jump in CPU  
utilization.  We were planning on adding another 200+ customers to  
this router in another larger batch, but I am now thinking that the  
NPE-300 will be overutilized if we do that.

--
Roger J. Weeks
Systems & Network Administrator
Mendocino Community Network