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High-level data link control

(also HDLC)

High-level data link control definition

High-level data link control (HDLC) is a standardized method used in computer networks to make sure data is transmitted accurately and reliably between devices. We use it for point-to-point and multi-point communications. At its core, it’s essentially a set of rules that computers follow to communicate with each other effectively.

See also: data link layer, point-to-point protocol

Here's how it works:

  • Frame structure: HDLC divides data into small chunks called frames. Each frame includes the actual data to be sent, as well as control information, which helps the receiving device understand how to handle the data.
  • Synchronization: HDLC ensures that both the sender and receiver are synchronized, meaning they are on the same page about when data transmission starts and ends. This prevents data from getting mixed up or lost during transmission.
  • Error detection: HDLC includes mechanisms to detect errors in the transmitted data. If it finds any, the receiving device can request to resend the data, ensuring that the information is received in full.
  • Flow control: HDLC also helps manage the flow of data between devices. It makes sure that the sender doesn't overwhelm the receiver with too much data too quickly, preventing data congestion and loss.
  • Modes: HDLC can operate in different modes, including normal response mode and asynchronous response mode , allowing it to adapt to various network configurations and requirements.
  • Compatibility: HDLC is widely used and supported by many network devices and protocols, making it a versatile choice for data communication.