Which OSI layer is responsible for assembling bits into frames, performing error detection, and handling flow control in Ethernet networks?

Which OSI layer is responsible for assembling bits into frames, performing error detection, and handling flow control in Ethernet networks?

• A. Data Link Layer (Layer 2)
• B. Physical Layer (Layer 1)
• C. Network Layer (Layer 3)
• D. Transport Layer (Layer 4)

Answer: (A)

Framing, error detection, and local flow control are functions of the Data Link Layer. It sits between the physical medium and the network layer, taking the raw bits from the Physical Layer and organizing them into frames with headers and a trailer. The trailer carries error-detecting information (for Ethernet, a CRC) so the receiver can verify a frame’s integrity and discard it if corruption is detected. It also manages flow control on the local link so a fast sender doesn’t overwhelm a slower receiver, using mechanisms like MAC-level control and PAUSE frames in Ethernet. For context, the Physical Layer handles the actual electrical or optical signaling and timing; the Network Layer handles routing and addressing between networks; the Transport Layer handles end-to-end reliability and flow control between endpoints.

Framing, error detection, and local flow control are functions of the Data Link Layer. It sits between the physical medium and the network layer, taking the raw bits from the Physical Layer and organizing them into frames with headers and a trailer. The trailer carries error-detecting information (for Ethernet, a CRC) so the receiver can verify a frame’s integrity and discard it if corruption is detected. It also manages flow control on the local link so a fast sender doesn’t overwhelm a slower receiver, using mechanisms like MAC-level control and PAUSE frames in Ethernet.

For context, the Physical Layer handles the actual electrical or optical signaling and timing; the Network Layer handles routing and addressing between networks; the Transport Layer handles end-to-end reliability and flow control between endpoints.