At 11:41 PM 3/24/96 -0500, Paul Ferguson wrote:

Kent,

Have you done any statistical gathering on the overhead required to route IP traffic in the Pac Bell ATM NAP? I'd be interested in seeing this, for certain. :-)

- paul

That's difficult to do on the ATM switch, and not really necessary since we can measure IP packet size any number of places and compute the ATM overhead. I have been doing some more arithmetic on the "ATM cell tax" to see if I can find out how folks get from 10% (which is the 5/53 overhead) to 35% overhead. I would really really like to see some backup for those sort of numbers -- I can't make the arithmetic work out to anything near 35% for what I think are useful assumptions. Of course, if you want to posit 100% of IP traffic with 49 bytes, but that doesn't seem realistic and you shouldn't forget that 40 of those are TCP/IP overhead. :-) What traffic mix do you use to calculate ATM overhead and what results do you get? --Kent