Which OSI layer is responsible for breaking up packets into frames for transmission?

The correct answer pertains to Layer 2 of the OSI (Open Systems Interconnection) model, which is known as the Data Link layer. This layer is responsible for various functions, including framing, which involves taking data packets from Layer 3 (the Network layer) and encapsulating them into frames for transmission over the physical medium.

Layer 2 adds headers and trailers to the packets to create frames, thus ensuring proper addressing and error detection. By establishing a link between the network layer and the physical layer, it also handles the physical addressing used for delivering frames within the same local network.

In the OSI model, Layer 1 is focused on the physical transmission of raw bitstreams over a physical medium, Layer 3 is responsible for logical addressing and routing of packets, while Layer 4 manages end-to-end communication and flow control. Therefore, the function of breaking packets into frames specifically falls under the responsibilities of Layer 2.