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2012-10-31

Data Transfer Rates

Knowing data transfer rates is an important piece in measuring network performance.

All of the different terms can be quite confusing and the main reason is because some people do not provide the correct, and descriptive labels for the amount of data that they are transferring.

All of the information I will be providing has been taken from: http://en.wikipedia.org/wiki/Data_rate_units

What I tend to do when converting units is to convert every unit into bits as that is the most basic unit of measurement (on or off)

Mb (Mbit - Megabit)   = 1 000 000 bits
MB (Megabyte)         = 8 000 000 bits
Mib (Mbits - Mebibit) = 1 048 576 bits
MiB (Mebibyte)        = 8 388 608 bits

kibi - means kilobinary which means 1 024 because when you count in binary you do binary counting you will notice that you never hit exactly 1 000 as you are counting in powers of two. This is the reason why Mib is specified differently from Megabytes or Megabits.

The confusion comes when manufacteurers of computer operating systems SAY they are using Megabytes when in reality they are measuring in Mebibits.

In "My Computer" on Windows you will see 60GB of free space but really, they should be using the notation GiB of space.

Example:
Switch traffic rate = 500071578 bits/sec

Megabits = 500071578/1 000 000 = 500.07 Mb/s
Mebibits = 500071578/1 048 576 = 476.91 Mbit/s

You can see how this would be potentially confusing for someone as you're missing out on bits if you use mebibits in one place where someone else may have standardized on megabits.

So in conclusion, when measuring bits and bytes and kilobits and kilobytes. Ensure you are using the proper notation to avoid confusion.


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