Which OSI layer sits directly above the Physical layer and handles framing and MAC addressing in Ethernet networks?

• A. Physical Layer (Layer 1)
• B. Data Link Layer (Layer 2)
• C. Network Layer (Layer 3)
• D. Application Layer (Layer 7)

Answer: (B)

Framing and MAC addressing happen at the Data Link layer, which sits directly above the Physical layer. This layer is responsible for turning the raw bits that come from the physical medium into usable data units called frames. Each frame includes a header with the source and destination MAC addresses, and often a trailer with error detection information, so two devices on the same local network can communicate reliably.

Within the Data Link layer, the MAC sublayer handles how access to the physical medium is managed and carries the MAC addresses that identify devices on the LAN. The LLC sublayer provides a stable interface for multiple network layer protocols, but the actual addressing and framing you see on Ethernet are functions of the Data Link layer.

The Physical layer, in contrast, deals with the actual electrical or optical signals and timing—bits on the wire, not structured frames. The Network layer handles logical addressing and routing (IP addresses, paths between networks), while the Application layer deals with end-user protocols and software. So the layer that directly above the Physical layer and responsible for framing and MAC addressing in Ethernet is the Data Link layer.