The basic billing model for bandwidth. Typically, a customer is paying for the greater of inbound or outbound traffic. Traffic is divided into 5 minute intervals, and the 95th percentile is used for billing.

Typical extensions to this include:

Committed Rate
This is the rate a customer will pay for, whether or not they actually use that amount of bandwidth. It is also used for computing various premium charges.
Exceed Rate
If the 95th percentile is higher than the committed rate, the customer typically pays a premium (usually about 125% of the committed rate cost) on this traffic.
Burst Rate
For all traffic which exceeds the Committed Rate by some multiple (usually 4x), the customer pays a burst rate, which is often a bit-based exorbitant cost.
The equation looks something like this:
C = committed rate
P = price at committed rate
R95 = 95th %ile rate
Ri = index of rate values
T = burst rate threshold

Price =
(C * P)
+ (max(0,R95-C)* E* P)
+ sum (all i, if(Ri > T, Ri*B*P))

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