Error Control in Data Link Layer

Error control is a mechanism that ensures that data transmitted over a communication channel is received accurately by the receiver. Error control is a mandatory service of the data link layer in computer networks. Let's discuss in detail how error control works in the data link layer.

What is the Data Link Layer?
The data link layer is the second layer of the OSI model. It is responsible for transmitting data between adjacent network nodes. The data link layer is divided into two sub-layers, the Logical Link Control (LLC) sub-layer, and the Media Access Control (MAC) sub-layer.

What is Error Control?
Error control is a mechanism that ensures that data transmitted over a communication channel is received accurately by the receiver. The error control mechanism detects and corrects errors that may occur during transmission. Error control is critical to ensure the reliability of data transmission.

How does Error Control work in the Data Link Layer?
Error control in the data link layer is achieved through two techniques:

1. Error Detection
Error detection is a mechanism that detects errors in the data transmitted over the communication channel. There are several error detection techniques such as cyclic redundancy check (CRC), checksum, and parity check.

2. Error Correction
Error correction is a mechanism that corrects errors in the data transmitted over the communication channel. The error correction technique used in the data link layer is called Automatic Repeat Request (ARQ). In ARQ, the receiver sends an acknowledgment message to the sender indicating whether the data has been received accurately or not. If the data is received with errors, the sender retransmits the data.

Conclusion
In conclusion, error control is a mandatory service of the data link layer in computer networks. Error control is achieved through error detection and error correction techniques. Error detection detects errors in the data transmitted over the communication channel, while error correction corrects errors in the data transmitted over the communication channel.