17 Sep 08 95th percentile billing explaination

95th percentile billing commonly misspelled as “percential” is a method used by some NOCs to change for bandwidth.

The system is simple and essentially discards the top 5% of your traffic peaks, and then uses the next value down as your bandwidth rate. 5% of a month is 36 hours. This might sound like a bit of a scam, because you’re being billed for bandwidth consumption that you may not have used, but it’s not difficult to get it to work for you.

If you’re hosting a site where a lot of content is downloaded, it may be better to go for bandwidth billing. A client’s content server uses about 8,000GB transfer per month and shows a 95th percentile of 34mbit/sec. It’s certainly cheaper to pay for 8,000GB transfer over 30+mbit/sec dedicated.

Other servers are connected to a 95th percentile billing system in my setup. These servers if left unrestricted would peak at about 40mbit and possibly hit a 95th percentile value of about 7mbit, however I’d rather pay for 4mbit. I set my traffic limiter to 4mbit/sec allowing a 2.8 second per minute (<95%) random burst. 4mbit solid per month allows me a total transfer of 1307.8125GB. Seeing as 5% is unbilled, I could theoretically burst at 100mbit/sec solid for 36 hours allowing me an extra 1406.25GB of transfer. Should I burst at 100mbit/sec for 37 hours though, I’ll be charged for 100mbit/sec. This is entirely theoretical and doesn’t actually match real life traffic trends but serves as a good explaination.

Tags: 95th, 95th percential, 95th percentile, bandwidth consumption, bandwidth management, bandwidth rate, burst, content, datacenter, download, Hosting, limiting, noc, peak, peaks, servers, shaping, traffic, traffic peaks

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