What are error detection codes? Explain checksum with necessary example.

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Bipin Tiwari · Accepted Answer

Errors and Error Detection: When bits are transmitted over the computer network, they are subject to get corrupted due to interference and network problems. The corrupted bits leads to spurious data being received by the receiver and are called errors. Error detection techniques are responsible for checking whether any error has occurred or not in the frame that has been transmitted via network. It does not take into account the number of error bits and the type of error. For error detection, the sender needs to send some additional bits along with the data bits. The receiver performs necessary checks based upon the additional redundant bits. If it finds that the data is free from errors, it removes the redundant bits before passing the message to the upper layers. There are three main techniques for detecting errors in frames: Parity Check, Checksum and Cyclic Redundancy Check (CRC). Checksums: This is a block code method where a checksum is created based on the data values in the data blocks to be transmitted using some algorithm and appended to the data. When the receiver gets this data, a new checksum is calculated and compared with the existing checksum. A non-match indicates an error. Error Detection by Checksums: For error detection by checksums, data is divided into fixed sized frames or segments. Sender’s End − The sender adds the segments using 1’s complement arithmetic to get the sum. It then complements the sum to get the checksum and sends it along with the data frames. Receiver’s End − The receiver adds the incoming segments along with the checksum using 1’s complement arithmetic to get the sum and then complements it. If the result is zero, the received frames are accepted; otherwise they are discarded.

What are error detection codes? Explain checksum with necessary example.

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What are error detection codes? Explain checksum with necessary example.

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