Which layer of the OSI model is responsible for end-to-end communication?

The Transport layer is responsible for end-to-end communication in the OSI model because it ensures that data is transferred from the source to the destination application reliably and without errors. This layer manages the segmentation of data, flow control, and error checking, providing the necessary functionalities to maintain a stable communication session.

By establishing a connection between the sender and receiver, the Transport layer can manage how much data is sent and ensure that messages can be reassembled in the correct order at the receiving end. Protocols like TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) operate at this layer, with TCP focusing on reliability through error correction and acknowledgment, while UDP offers faster, connectionless communication.

Other layers play specific roles in the OSI model; for instance, the Network layer primarily handles addressing and routing packets across networks but does not ensure the integrity of the communication. The Session layer manages sessions between applications, coordinating their interactions but not the end-to-end communication itself. The Application layer interfaces directly with user software and provides network services but relies on the functionality of the lower layers for data transport.