Explanation of Average Rate and Peak Rate on the PacketShaper

Products

• PacketShaper S-Series

Issue/Introduction

You want to know what mechanisms and variables are used to calculate the Average Rate (avg-bps) and Peak Rate (peak-bps) for the PacketShaper.

Resolution

By definition, average rate is the average bits per second during the interval and peak rate is the peak or the highest bits per second during that interval.

The PacketShaper keeps count of the incoming and outgoing bytes for the link as well as all the classes. Average bits per second is calculated based on the number of bytes it counted and the interval specified.  The formula used is:

• avg-bps = (Total bytes during the interval  x 8) / Time interval in seconds

While we are counting bytes for all the incoming and outgoing flows we also meter the current bits per second for each class. The current bits per second is calculated 8 times every second that allows you to monitor a burst in traffic even for a very small period of time. This current rate value is used to calculate the peak-bps.

The peak-bps is the highest current bps during that interval. For example: if you want to know the peak-bps for a class during the time of 10:00 to 10:01, it will be the highest current bps during the period of 10:00 to 10:01 (highest among the several current bps values during that minute). The peak-bps is calculated every minute internally and stored in our Measurement Engine. Only one minute samples are coming directly from the current bps calculation; for any higher interval, it is calculated using the one minute peak bps from the ME. For example: if you want to know the peak-bps for an hour interval, it will be the highest value between the 60 one minute peak-bps stored in the ME for that hour.