router performance benchmark

[vbajaj portal stwing upenn edu]

Hello,

I now have the unenviable task of implementing a VPN for a client
using Linux routers, with VPN<--> internet
controlled/filtered/proxied.  All trivial to do, and I've done it
before, just with slower leased lines or with dedicated hardware
(e.g. Cisco IP GRE) on faster networks.  

The trouble is that I can't find any hardware benchmarks, obviously,
so I thought that one of you might have done this before.  What is the
sort of latency, process bandwidth etc. can I expect with midrange
Pentium machines, a VPN across five subnets (with about 5 machines per
subnet), connected locally by switch?

--Vik