Final answer:
The data link layer adds a frame header and frame trailer to a Layer 3 packet to create a frame, including MAC addresses and error-checking information like a CRC.
Step-by-step explanation:
The data link layer is the second layer from the bottom in the OSI (Open System Interconnection) network architecture model. It is responsible for the node-to-node delivery of data. Its major role is to ensure error-free transmission of information.
It is also responsible for adding certain elements to a Layer 3 packet to convert it into a frame. These elements include a frame header and a frame trailer.
The frame header typically contains a start of frame indicator, source and destination MAC (Media Access Control) addresses, and error-checking functionalities, often represented by a frame check sequence (FCS).
The frame trailer, mainly, contains error detection information, typically a cyclic redundancy check (CRC). These additions ensure that the data can be properly transmitted over the physical medium, providing mechanisms for addressing, error detection, and control of data flow.