Understanding 95th Percentile Billing
95th percentile billing charges for the bandwidth your connection uses on a regular, sustained basis, not for its brief spikes. DLS Communications measures your usage every five minutes, sorts the billing period’s measurements, discards the highest 5%, and bills on the highest measurement that remains. Your usage is at or below that figure 95% of the time.
How DLS Calculates the 95th Percentile
1. Measure Every 5 Minutes
The DLS statistics system collects a sample from its routers and switches every five minutes. Each sample is the average bits per second over those five minutes.
2. Sort and Discard the Top 5%
At the end of the billing cycle the samples are sorted. The highest 5%, the short spikes of atypical usage, are discarded.
3. Compare to Your Contract
The highest remaining sample is your 95th percentile. If it is above the bandwidth your contract allows, you are charged overusage on the difference.
What the Top 5% Means in a Month
With a sample every five minutes, a 30-day billing period holds 8,640 samples. Discarding the highest 5% removes 432 of them, which is 36 hours of your busiest traffic. Backups, large downloads and other bursts that add up to less than that do not raise your bill.
The 95th percentile is not an average. It represents the bandwidth you actually used during all but the busiest 5% of the period, so it is normally higher than your average and lower than your peak.
A Graphical Example
This is a typical month-view graph of a co-located server. Traffic peaks and falls every day, with a maximum inbound rate of 2.61 megabits per second. Removing the top 5% of the samples puts the 95th percentile at 1.37 megabits per second, while the average for the month is 823 kilobits per second.
This customer would be billed at 1.37 megabits per second for the month, assuming the billing cycle ended on the last day shown.
Maximum: 2.61 Mb/s
The single busiest five minutes of the month. Not used for billing.
95th Percentile: 1.37 Mb/s
The highest sample left after the top 5% are discarded. This is the billed rate.
Average: 823 Kb/s
The month's average. Lower than the 95th percentile, and not used for billing.
95th Percentile Billing FAQ
A way of billing bandwidth on regular, sustained use rather than peaks. Usage is sampled every five minutes, the highest 5% of samples in the billing period are discarded, and the highest remaining sample is the billed rate. Your usage is at or below that rate 95% of the time.
The DLS statistics system samples its routers and switches every five minutes, each sample being the average bits per second over those five minutes. At the end of the billing cycle the samples are sorted, the top 5% are discarded, and the highest remaining sample is used by the DLS billing system.
5% of the samples. In a 30-day billing period that is 432 of 8,640 five-minute samples, or 36 hours of the busiest traffic.
No. The 95th percentile is normally higher than the average and lower than the peak. In the example on this page the average is 823 Kb/s, the 95th percentile is 1.37 Mb/s and the peak is 2.61 Mb/s.
DLS compares your 95th percentile with the bandwidth your contract allows. If it is higher, you are charged overusage on the difference. Your contract lists your allowance and overusage price, or ask your DLS sales representative.
Questions About Bandwidth Billing?
For the bandwidth allowed on your DLS connection and the overusage price, check your contract or ask your DLS sales representative. Call 800-323-2099.