What is 1Mbps 95th percentile ?
1mbps 95th percentile means you can use the full 100mbps connection, but 95% of the time you're at or below 1mbps of actual usage. You'll hear varying guesses of how much data you can actually transfer, but I usually estimate that each mbps is 330GB up or down.
Think of it in terms of water.
Your provider is offering to give you a 100 gallons per second pipe to your house. You're welcome to use that entire pipe should you have the need for a lot of water at any given time, which is handy because that allows you to shower, water your lawn, and run the dish washer all at the same time. If you only had a 1 gallon per second pipe to your house, you wouldn't be able to multitask like that.
But lets face it, most of the time (say...23 hours a day) you're not using 100 gallons per second, so you don't want to be billed for that much. There are two ways the water company can measure your water usage. They can either count the gallons you actually use (like metered transit plans measured in GB transferred) or they can bill based on the the quantity you're usually using at any given time, such as 5 gallons per second (like 95th percentile measuring bandwidth in mbps.)
The reason datacenters might want to measure in megabits per second is because it's the best way to do capacity planning.
Michael Gazzerro is a senior account manager at www.ubiquityservers.com.