[c-nsp] 6500 netflow export and the switch cpu

[sthaug at nethelp.no]

> > Highly unlikely. Sampling on the 6500 is performed interely in
> > software, *after* the full set of flows has been received.
> 
> You have to distinguish between the cpu load seen as interrupt load 
> (caused mostly by walking through the TCAM, collecting statistics and 
> storing them in netflow cache) and the cpu load caused by NDE process 
> (packet generation). Enabling netflow sampling you can decrease the 
> second part of the load - the cpu will generate significantly less 
> packets of export statistics.

Good point. And it doesn't help, of course, that the CPU in question is
severely underpowered...

Steinar Haug, Nethelp consulting, sthaug at nethelp.no