Which data link layer sublayer is responsible for controlling access to the physical medium?

Which data link layer sublayer is responsible for controlling access to the physical medium?

• A. MAC
• B. LLC
• C. Network
• D. Transport

Answer: (A)

Access to the physical medium is managed by the MAC sublayer. It sits at the data link layer and governs how devices gain access to the shared channel, coordinates transmissions, and handles hardware addressing and frame boundaries. Techniques like CSMA/CD in Ethernet are MAC functions. The LLC sublayer above it provides logical link control and multiplexing between higher-layer protocols, but it doesn’t control when or how devices transmit on the medium. Higher layers (network, transport) operate above this layer and aren’t involved in medium access.

Access to the physical medium is managed by the MAC sublayer. It sits at the data link layer and governs how devices gain access to the shared channel, coordinates transmissions, and handles hardware addressing and frame boundaries. Techniques like CSMA/CD in Ethernet are MAC functions. The LLC sublayer above it provides logical link control and multiplexing between higher-layer protocols, but it doesn’t control when or how devices transmit on the medium. Higher layers (network, transport) operate above this layer and aren’t involved in medium access.