Which layer's responsibilities include framing, error detection, and flow control in LAN technologies such as Ethernet?

Which layer's responsibilities include framing, error detection, and flow control in LAN technologies such as Ethernet?

• A. Physical Layer (Layer 1)
• B. Network Layer (Layer 3)
• C. Session Layer (Layer 5)
• D. Data Link Layer (Layer 2)

Answer: (D)

Framing, error detection, and flow control are functions of the Data Link Layer. Framing means packaging the network data into frames with a header and trailer so the recipient can determine where each piece of data starts and ends on the local link. In Ethernet, the frame header includes destination and source MAC addresses, and the trailer carries a frame check sequence (CRC) used to detect errors that may have occurred during transmission. Flow control helps prevent the sender from overwhelming the receiver’s buffers; on Ethernet this is implemented with mechanisms like 802.3x Pause frames that briefly halt transmission when needed. The Data Link Layer sits between the Physical Layer and the Network Layer, handling reliable transfer between adjacent devices on the same network segment. The Physical Layer just transmits raw bits, the Network Layer focuses on routing and logical addressing across networks, and the Session Layer manages dialog control—none of these perform the framing, error detection, and flow control tasks that the Data Link Layer handles on a local link.

Framing, error detection, and flow control are functions of the Data Link Layer. Framing means packaging the network data into frames with a header and trailer so the recipient can determine where each piece of data starts and ends on the local link. In Ethernet, the frame header includes destination and source MAC addresses, and the trailer carries a frame check sequence (CRC) used to detect errors that may have occurred during transmission. Flow control helps prevent the sender from overwhelming the receiver’s buffers; on Ethernet this is implemented with mechanisms like 802.3x Pause frames that briefly halt transmission when needed. The Data Link Layer sits between the Physical Layer and the Network Layer, handling reliable transfer between adjacent devices on the same network segment. The Physical Layer just transmits raw bits, the Network Layer focuses on routing and logical addressing across networks, and the Session Layer manages dialog control—none of these perform the framing, error detection, and flow control tasks that the Data Link Layer handles on a local link.