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Foreshore’s 95th Percentile Bandwidth Billing – Explained

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Foreshore’s 95th Percentile Bandwidth Billing – Explained


Foreshore bills all burstable bandwidth usage using a 95th Percentile calculation.  But what exactly does this mean?  Well, to ensure that billing is carried out as fairly as possible, we will take samples of your bandwidth usage every 5 minutes throughout the day and then remove the top 5% of these.  This means that, should you slip over your allocated bandwidth for a short period during the month, you will not incur overage changes as long as it falls within 5% of the total amount of samples taken for that month.

 

For example, assuming that a standard month is comprised of 30 days, the number of samples based on a 5 minute sampling interval is 8640 (12 samples per hour x 24 hours per day x 30 days. The top 5% of these samples equates to 432 individual measurements which represents 36 hours.  As a result, a standard burstable service (1Mb/s burstable to 4Mb/s) will allow you to use in excess of 1Mb/s for a total of 36 hours per month without incurring any overage charges.

 

The following scenarios demonstrate how 95th percentile billing functions with different bandwidth profiles (note: all examples assume a 1Mb/s to 4Mb/s burstable service and a 5 minute sampling period).

 

Scenario 1

Bandwidth use is fairly constant throughout the day with never more than 900Kb/s being used in either direction. Between 13:00 and 14:00, traffic levels increase to 3.7Mb/s. This results in 12 samples per day (or 1 hours worth) being above the standard 1Mb/s rate. Over a month this equates to 360 samples or 30 hours with the resulting 95th percentile value being below the 1Mb/s mark.

 

Scenario 2

Bandwidth use is fairly constant throughout the day with never more than 900Kb/s being used in either direction. Between 13:00 and 14:30, traffic levels increase to 3.7Mb/s. This results in 18 samples per day (or 1.5 hours worth) being above the standard 1Mb/s rate. Over a month this equates to 540 samples or 45 hours with the resulting 95th percentile value being significantly higher than the 1 Mb/s mark.

 

Using the above examples, it is clear to see how a seemingly insignificant change to a bandwidth profile can have a major impact on the 95th percentile value.

 

The following screen capture contains profile details that show bandwidth “occasionally” exceeding 4Mb but with significant periods where the usage is much lower. The 95th value for the traffic denoted by the green section of the graph, is, however 4.6Mb/s which would result in an overage charge.

 
4Mb/s  burstable to 8Mb/s


 
The following capture shows a different profile with traffic in both directions occasionally reaching the maximum permitted limit but with generally a much lower general usage. The 95th percentile value is, as expected, below the 512k overage free limit.

 

512k burstable to 2Mb/s

 



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Last Modified:01/08/2013 09:58:02

Last Modified By: alanm

Type: INFO

Rated 5 stars based on 1 vote

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