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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: 95th Percentile = Lame
On Sun, 3 Jun 2001, James Thomason wrote: > > > If I am not mistaken, the true "benefit" to 95% billing is that it allows > the provider to charge for bits they never delivered. The average will > skew on a burst of traffic (>5% of the average) and you pay for it as if > you had averaged that level the entire time. James: I think the others have made the point regarding the above comment. However, let me explain my view of this a bit differently. As pointed out, the providers have to build to provide a certain quality of service during peak hours. It's the behavior of their network at those peak hours that determines what they need to build/buy and therefore their costs, which then determines what they need to charge their customers. Personally, I think the 95% billing is a rational simplification of a more complex problem. If you accept that peak loading occurs for something around 3-4 hours/day (sounds about right) and that 95% billing ignores the top 1.2 hours of usage each day, it's kind of like drawing a line horizontally roughly midway up the usage curve during the few hours of peak usage. In a way, it's what others have refered to as "average peak" usage. If you don't assume that a customer's usage is a smooth curve, but rather has some random variability during the few hours around peak loading time, and you assume that you have enough customers with similar somewhat random variations that those variations average out over the bulk of all customers to be a somewhat smooth loading, then you can only come to one conclusion. You can rationally evaluate, provision and bill for, that "average peak" usage of your network and have some level of confidence that you're being fair not only to yourself, but also your customer. As I see it, the only way to be even more fair, would be to truely average a customer's peak usage using some kind of "rolling average" calculation, then take the peak of that rolling average. That would possibly be more fair to customers who have wierd peak usage curves which could skew the 95% value to the point where it is NOT a reasonable estimation of the customer's average peak usage. Chuck Scott
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