GoFuckYourself.com - Adult Webmaster Forum

here ya go...it's alot but its accurate =)

Billing Methods Explained:

There are three common types of billing methods that IPPs generally use to bill their dedicated server customers; the "95th percentile", "bandwidth average", and "per gigabyte" based billing. All have their distinct advantages though we feel that the "95th percentile" method is the most balanced overall method.
Let's start with the "per gigabyte" based billing. Anyone familiar with "shared server" hosting is likely to be quite familiar with this type of billing. Quite simply, log files are kept of your web activity throughout the month and then at the end of the month you pay a specific charge for each gigabyte of data you transferred.

"per gigabyte" based billing usually includes both your incoming and outgoing data transfer -- so if you transfer 3000 gigabytes of outgoing transfer and 1000 gigabytes of incoming transfer then you are billed for a total of 4000 gigabytes of transfer.

The second common method of billing is "bandwidth capped". With this type of billing you select a bandwidth "cap" (usually in increments of 1 megabit per second) and you are restricted from transferring data beyond your "cap" amount. For instance, if you purchased a 20 megabit bandwidth cap then your web sites are free to transfer as much data as they need, up to 20 megabits per second. If you try to transfer beyond 20 megabits per second then your traffic is "slowed down" so that you cannot break the 20 megabit per second barrier.

"bandwidth average" based billing is usually for a "full duplex" network connection. This means that if you purchase a 20 megabit per second connection then you can transfer 20 megabits of incoming transfer and 20 megabits of outgoing transfer at the same time.

The "95th percentile" based billing is sort of a hybrid between the previous two billing methods. Throughout the month your incoming and outgoing bandwidth is graphed in five minute intervals. Every five minutes your transfer is totaled for the previous five minutes and an average transfer rate is derived. From that data a graph is created to show you your "real-time" bandwidth usage:

- Real-Time Bandwidth Graphs (updated every five minutes)

For example, if during the five minute interval you had 300 megabytes of outgoing transfer and 30 megabytes of incoming transfer your average outgoing transfer rate would be 8 megabits and your average incoming transfer rate would be 0.8 megabits. For reference, 8 megabits equals 1 Megabyte of data transferred every second (multiplied out for 300 seconds -- five minutes -- you get a total of 300 Megabytes of data transferred).

After the five minute samples are calculated the lowest of the two samples (usually the incoming data sample) is tossed out and the highest of the two samples (usually the outgoing data sample) is kept. This in effect gives you free incoming data transfer since the smaller of the data samples is tossed out completely.

At the end of 30 days we have 8,640 samples. At that time the top 5% of the samples (432 samples -- 36 hours worth) are tossed out. You are then billed on the highest remaining sample. This gives you 36 hours of transfer for free (as well as already having half of the samples tossed out). You get the "free" incoming bandwidth of "bandwidth valved" based billing as well as the burstability of "per gigabyte" billing. The best of both worlds.

"95th Percentile" versus "Bandwidth Valved"
The largest advantage of "bandwidth valved" billing is the predictable monthly costs. If you buy 20 megabits of bandwidth then you are charged for exactly 20 megabits of bandwidth.
There are, however, several drawbacks to "bandwidth valved" billing. The single largest drawback is the fact that you need to "buy to the peak". The traffic patterns for all web sites are filled with peaks and valleys. No web site in the world transfers a steady amount of bandwidth.

If, for instance, you have a web site that transfers around 8 megabits per second during the off-peak hours but bursts to around 20 megabits during the busy period of the day then you'll want to make sure you purchase 20 megabits if you're purchasing "valved" bandwidth. If you purchase less than 20 megabits -- say perhaps 15 megabits -- then your web sites will run noticeably slower during the peak times.

To make matter worse, when you purchase 15 megabits and your web sites are only doing 8 megabits in the off-peak times you are in effect paying for bandwidth that you are not using.

That leaves you in the situation where your web sites run slower during the peak times because you didn't purchase enough bandwidth and then you're paying for unused bandwidth in the off-peak times.

This is where the advantages of the 95th percentile billing shine. Because your bandwidth is not valved in any way, your web sites are free to burst to "full fast ethernet speed" during the peak times -- if it bursts to 20 or 25 megabits then that is what is sampled and recorded -- but during the off-peak times you'll only be paying for 8 megabits. You do not need to worry about having to "upgrade" your service just because you plan on increasing your usage later on in the month, and it takes the guess-work out of trying to figure out exactly how much bandwidth you really need.

Then, at the end of the month, your top 5% of the samples are tossed out. You get 36 hours of free transfer and you do not have to buy extra bandwidth just to sustain your peak times.

When it's all said and done, at the end of the month you may have had to purchase 20 megabits of "valved" bandwidth, but your 95th percentile may only be 13 megabits.

Combining Bandwidth Valving with 95th Percentile Billing
Looking for the predictability of valved bandwidth with the burstable connectivity of 95th percentile? No problem. All of our virtual servers have bandwidth valving capabilities built-in. If you have a web site that transfers between 10 and 20 megabits, for example, we can valve that virtual server at 20 megabits to insure that you never exceed the 20 megabit threshold. The billing will continue to be on the 95th percentile, so if at the end of the month your 95th percentile shows your bandwidth usage at 13 megabits you pay for only 13 megabits.
This gives you a virtual "ethernet pipe" and guarantees that your transfer will not exceed that amount -- just as with bandwidth valving -- along with the superior pricing model of the 95th percentile billing.

enjoy