[c-nsp] 7513 T3 Card Question

[David Coulson]

Paul Stewart wrote:
> My question hopefully has a quick and generic answer... if you don't have
> enough CPU (RSP or VIP) what would the indicator be that you need to
> upgrade?  Dropped packets, high CPU??

After spend a lot of time working on 7500s, if you get the configuration 
correct there should be very little CPU usage on the RSP since 
everything should be dCEF switched. Unless you start running features 
that cause packets to be punted to the RSP, you should be able to scale 
it pretty easily (Our 7500s running ~10% CPU 24/7, going up to ~15% 
during biz hrs, but like I said, I spent a long time tuning stuff). CPU 
usage on my devices doesn't seem to significantly represent bandwidth 
consumption.

You can look at individual VIP CPU usage too however. For example, a 
VIP2-50 with a single PA-MC-T3 (running 28 full DS-1 spans) maxes out at 
30% and only indicates a 10% average CPU load during business hours. I'd 
think that the CPU usage on the VIP would be dependent only upon PAs on 
the card, rather than the rest of the router.

The nice thing to remember is that you'll start dropping process 
switched packets long before you have issues with route-cache or dCEF 
switched packets. If your NMS is pinging your router, you'll see dropped 
packets there before it massively effects any interfaces.