On a LAN, the data link layer uses the MAC address of the destination machine rather than the IP address. The data link layer has a frame header that contains the source and destination MAC address, which is also referred to as a physical address. The trailer, or frame check sequence, holds a value called a Cyclic Redundancy Check (CRC), which is used for error detection on a network.

The following chart provides a summary of the data link layer:

The data link layer ensures proper frame formation and link access, along with error detection, while traveling across the network media. Data then travels on the physical layer, as we will see in the following section.