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Re: 95th Percentile again (was RE: C&W Peering Problem?)

  • From: Joe Abley
  • Date: Sat Jun 02 22:01:27 2001

On Sat, Jun 02, 2001 at 05:28:52PM -0400, Timothy Brown wrote:
> As an interesting aside to this discussion, Digital Island bills for 
> total traffic transmitted per month (in GB increments).   Does anyone 
> using them have any comments on this approach besides the obvious?  Does 
> anyone else do a similar deal?

This may be obvious, but billing by volume (bytes transferred) places far
greater availability requirements on the measurement system than rate-based
charging schemes.

If I am charging by the byte, I have to count every packet. If my measurement
system breaks, I lose money until it is fixed.

If I am charging by the 95%tile of five-minute average throughput measurements
obtained during a calendar month, I can make do with much more coarse-grained
sampling. Measurement system breaks, I'm quite possibly going to bill the
same amount as if it hadn't broken.

Do Digital Island contracts specify any interpolation they are permitted to
do in the event that their traffic data acquires black spots? Or is their
measurement platform good enough to be able to count every packet reliably
without loss?

As to other examples, volume charging is still quite common in New Zealand;
people have been counting bytes and charging by the gigabyte there since
the first 9k6 circuit connecting the University of Waikato to NASA went live
in April 1989. See

  http://www2.auckland.ac.nz/net/Accounting/nze.html

"New Zealand Experiences with Network Traffic Charging" by Nevil Brownlee
if you're interested in the history.


Joe