On Sat, 2 Jun 2001, Joe Abley wrote:
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.
No, you are confused. A rate based billing system polls a byte counter on a switch or router at set intervals (ex: every 5 mins), subtracts the previously recorded value, and divides by the number of seconds in that interval. If the polling system cannot reach the device it is monitoring, samples can be missed, this is a very old problem of rate-based monitoring. Every rate-based system of which I am aware orders these "samples" to calculate 95th percentile, so a missed sample is equivilent to a 0 sample. A rate can be interpolated for the missing time, but it is pretty much guaranteed not to be accurate, and I'd suspect a case could be made against a provider who "makes up numbers" because of a failure in their billing system. A volume based billing system on the other hand, could theoretically poll only once a billing period. In reality it would probably poll more often, both to keep the customer apprised of their currently used amount, and to prevent the possibility of counter rollovers, but it would never "miss" a billing sample. -- Richard A Steenbergen <ras@e-gerbil.net> http://www.e-gerbil.net/ras PGP Key ID: 0x138EA177 (67 29 D7 BC E8 18 3E DA B2 46 B3 D8 14 36 FE B6)