What is the function of the Link layer in the OSI model?

The function of the Link layer in the OSI model is primarily concerned with ensuring a reliable transfer of data frames over a physical medium. It provides a means for devices on the same local area network (LAN) to communicate with one another effectively.

In detail, this layer is responsible for several key functions including framing, addressing (such as MAC addresses), and error detection and correction. When devices send data on the same physical network segment, the Link layer encapsulates the data into frames, which contain not just the payload but also source and destination MAC addresses, and manages error-checking to confirm that the data sent is received correctly. If any discrepancies are found, the Link layer can handle retransmission to ensure data integrity.

This role is crucial for local communications, as it makes certain that the devices on the same network can transfer frames without error, forming the backbone of proper data communication before the data can be passed up to higher layers of the OSI model.

Other answers reference functions of different layers in the OSI model, such as routing across multiple networks, providing end-user services, or managing sessions between applications. Each of those tasks falls to higher layers, distinctly separating their roles from the Link layer's main responsibilities.