Which LLC sublayer function is described as delimiting fields within a Layer 2 frame?

Which LLC sublayer function is described as delimiting fields within a Layer 2 frame?

• A. Adds Layer 2 control information to network protocol data.
• B. Places information in the frame that identifies which network layer protocol is being used for the frame.
• C. Implements a process to delimit fields within a Layer 2 frame.
• D. Integrates various physical technologies.

Answer: (C)

Delimiting fields within a Layer 2 frame is the job of the LLC sublayer by defining the frame header structure (DSAP, SSAP, and the Control field) and marking where the payload begins. This framing allows the receiver to parse the frame correctly, understand how to interpret the control information, and determine which upper-layer protocol’s data is being carried. In other words, LLC sets up the boundaries inside the frame so the payload can be properly extracted and, if needed, multiplexed to the appropriate network-layer protocol. The other aspects—adding Layer 2 control information, identifying the network-layer protocol for multiplexing, or integrating various physical technologies—are related but do not describe the act of delimiting the frame’s fields.

Delimiting fields within a Layer 2 frame is the job of the LLC sublayer by defining the frame header structure (DSAP, SSAP, and the Control field) and marking where the payload begins. This framing allows the receiver to parse the frame correctly, understand how to interpret the control information, and determine which upper-layer protocol’s data is being carried. In other words, LLC sets up the boundaries inside the frame so the payload can be properly extracted and, if needed, multiplexed to the appropriate network-layer protocol. The other aspects—adding Layer 2 control information, identifying the network-layer protocol for multiplexing, or integrating various physical technologies—are related but do not describe the act of delimiting the frame’s fields.