What is Checksum?

Checksum is a method which is used in Network Management to detect errors occured during transmission.

In this methods all the data segments are added using ones complement method, and then result is complemented. This complemented result is known as checksum and it is appended to data. Now original data segments and checksum is transmitted across the network.

Receiver adds all the received segments and if the result is all 1's then the data received is error free and it is accepted by receiver.

Example :-

Sender's data 00000010     01010000

Add these segments using ones complement arithmetic:

00000010

01010000

-------------------

01010010           Result

--------------------

Now complement the result

10101101           Complemented Result (Checksum)

Now append this checksum at the end of original data segments

00000010          01010000       10101101

Data Received at Receiver end

00000010          01010000       10101101

Now Receiver will add these sagments

00000010

01010000

10101101

-------------------

11111111        Sum

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Because sum is all Ones it means data is received error free.