[nsp] Real world L2TP PXF performance increases

[sthaug@nethelp.no]

> A previous post on this list cited 1500 L2TP sessions as a real world
> limit on an NPE-300 LNS.
> 
> Now that L2TP is PXF accelerated in 12.2(4)B, what real world
> performance improvements (if any) could be expected between an NPE-400
> and an NSE-1?  For example, Cisco quotes a 65% improvement for PPPoA
> (rather than L2TP) but this is in the same FAQ claiming an NPE-400 can
> support 8000 sessions :-)

Note that this depends a *lot* on how many session connects/disconnects
you have per second. We found this out the hard way when trying to use
NPE-300 for L2TP termination of dialup customers (typically 2 x ISDN 
BRI). Our boxes were getting killed by the signalling, not the actual
L2TP packet shuffling.

If you're doing PPPoA for ADSL customers, your signalling rates will be
much lower, of course.

Steinar Haug, Nethelp consulting, sthaug@nethelp.no