What happens at the data link layer in the network model?

The Data Link Layer is responsible for data transfer between neighboring nodes in a network over a physical communication channel.

This layer performs:

1. Framing: Dividing the data stream received from the network layer into frames and adding header and trailer information.
2. Media Access Control (MAC): Defining rules for how multiple devices can use a shared physical medium without conflicts (e.g., Ethernet CSMA/CD, Wi-Fi CSMA/CA).
3. Physical Addressing: Using MAC addresses to identify the source and destination of frames within a local network.
4. Error Detection and Correction: Adding checksums (e.g., CRC) to frames to detect transmission errors and, in some protocols, mechanisms to correct them.
5. Flow Control: Regulating the data transmission rate between neighboring nodes to prevent sender overload.

Examples of data link layer protocols include Ethernet, Wi-Fi (802.11), PPP, HDLC, and Frame Relay.