95th Percentile Explained
 Some of our clients are billed on the 95th percentile depending on their bandwidth needs. 95th Percentile means that you pay as you use the bandwidth with the advantage of spiking large amounts of traffic without fear of being billed overage. We usually will take one reading every 5 minutes generating a average traffic amount over a given 5 min duration.
At the end of the month the numbers are lined up, highest to lowest. If there are 100 readings, the top five percent will be discarded, and the 95th reading will be the measure of the level of bandwidth used and billed. Of course, there are many more than 100 samples (about 8,640 per month), so we remove the top five percent leaving the 95th percentile. The amount of samples removed per month on average usually equals 36 hours of unbilled traffic.
Short 95th examples
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Example 1:
Over a period of 500 minutes, 100 readings are taken of both incoming and outgoing traffic. If the billing period was also 500 minutes, the top 5% (Highest traffic ussage) of these readings (5 in this case) are ignored, and you are billed at the value of the 95th reading.
If the top 10 readings of this set of 100 were:
Recorded Traffic
Poll - 100 : 640Kbps
Poll - 99 : 440Kbps
Poll - 98 : 170Kpbs
Poll - 97 : 69Kbps
Poll - 96 : 40Kbps
Poll - 95 : 30Kbps - Billed Usage
Poll - 94 : 28Kbps
Poll - 93 : 27Kbps
Poll - 92 : 24Kbps
Poll - 91 : 21Kbps
......
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You would be billed using the 30Kbps as your billed amount and charged overage based on your current signed commit.
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Example 2:
So for another example lets have a co-location customer with (1) 1u server and a contract for 1 meg of service. Normally, they use 1 to 2 megs a day of bandwidth. On Fridays, they download a large file that uses 5+ megs of bandwidth for 15 minutes. Using the 95th percentile calc, the 15 minutes you use every Friday would be thrown out because it's in the top 5%.These 15 Mins of traffic each friday create a 1 hour spike of traffic over the total months traffic in which we will be removing 36 hours worth before billing.
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