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95th Percentile Billing

From Lunarpages Web Hosting Wiki

The 95th percentile is commonly used to ascertain the amount to bill for bandwidth usage that is considered "burstable".

When using a service that includes bandwidth, you “commit” to consume a certain amount of bandwidth. If your monthly consumption of bandwidth is at or below this commitment level, there are no additional fees. On the other hand, if you go beyond your commitment level you are billed for the additional bandwidth you used.

Calculating your bandwidth usage:

  • Every 30 seconds our MRTG program takes readings off of the network switch that services your equipment. These readings give us the amount of network traffic that has passed through the port that services your equipment.
  • The traffic totals are bunched together in five minute totals. The totals then get converted into kilobits and are divided by the total number of seconds that have passed in order to obtain the entire amount of bandwidth that came into and out of your port communicated in kilobits per second (Kbps). Bandwidth is measured independently for both inbound and outbound traffic. We charge based on the higher of these two totals.

Each month the top 5% of the readings are removed for both inbound and outbound. The next highest reading ("the 95th percentile") is what we consider to be your bandwidth usage. It is what we look at to conclude if the commitment level was exceeded and, if so, also determines the amount of “overage” fees that would apply.

Below is an example:

After 500 minutes, 100 readings, of both incoming and outgoing traffic, are documented. For this example we will say that the billing period is also 500 minutes. The top 5% of these 100 readings (the top 5, in this case) are then disregarded, and the 95th percentile reading is determined to be your usage.

If the top 10 readings of this set of 100 were:

Top 10 Entry

Reading

Comment

100

2,080 Kbps

Ignored (top 5%)

99

1,670 Kbps

Ignored (top 5%)

98

1,310 Kbps

Ignored (top 5%)

97

890 Kbps

Ignored (top 5%)

96

860 Kbps

Ignored (top 5%)

95

814 Kbps

** "95th Percentile"

94

810 Kbps

93

793 Kbps

92

712 Kbps

91

710 Kbps


In the example, even though your traffic sometimes spiked up to speeds of 2,080 Kbps, your 95th percentile usage was 810 Kbps. So, if your commitment level was 1 Mbps (roughly 1,000 Kbps) of bandwidth, your usage would be well below your “commit.”

If you are consistently going over your commitment level, it may be wise to increase it in order to avoid the overage bills that come along with exceeding your “commit.” This can be accomplished with a quick phone call or email to us.

Can I view/monitor my usage? Yes. You can view and monitor your usage by going to http://cstats.lunarcolo.com/ and logging in with the username and password we have provided you. More information on bandwidth monitoring and even bandwidth alerting can be found [here].