[c-nsp] NPE-G1 PPS limitations

[dpinkard at AccessLine.com]

Lukasz, great information. Thanks!

> Because of the way PA-GE is connected to the bus, and the way GE
> ports on a NPE-G1 are connected to it's separate bus to CPU, you'll
> get drastically different performance.

> For the GE ports on NPE-G1 you can expect around 470kpps at 64B, for
> the traffic going from/to GE port on NPE-G1 to C7200-I/O-GE it's
> close to 380kpps at 64B, and going from/to PA-GE it's only around
> 120kkps at 64B. That'll depend on features, IOS train and the traffic
> characteristics of course but those are the baselines for empty
> config with CEF and 12.1 train. 12.2S and latest 12.4(15)T rebuilds
> should get better performance in the same scenario.

> PA-GE to PA-GE traffic maxes out at around 160kpps at 64B with NPE-G1
> and NPE-400 - so it's not limitation of CPU engine but a bus
> limitation.

> Please note, PA-GE was designed "for connectivity" before VIP4 was
> released for 7500 so it's pretty old linecard.