Layer 2 - The data link layer

The data link layer acts as the driver of the physical layer and controls its functioning. The data link layer sends data to the physical layer at the transmitting end and receives data from the physical layer at the receiving node. It also provides error detection and correction that might have occurred during transmission/reception at the physical medium, and also defines the process for flow control between the two nodes to avoid any buffer overruns on either side of the data link connection. This can happen using PAUSE frames in Ethernet, and should not be confused with flow control in higher layers.

Some of the protocols that operate at the data link layer are LAPB, 802.3 Ethernet, 802.11 WiFi and 802.15.4 ZigBee, X.25, Point to Point (PPP) protocol, HDLC, SLIP, ATM, Frame Relay, and so on.