Which OSI layer is responsible for end-to-end communication and port multiplexing?

Which OSI layer is responsible for end-to-end communication and port multiplexing?

• A. Transport
• B. Data Link
• C. Network
• D. Physical

Answer: (A)

End-to-end communication and port multiplexing are functions of the transport layer. This layer ensures data is delivered between the correct processes on different hosts, handling segmentation, reassembly, flow control, and error checking. It also uses port numbers to distinguish multiple applications on the same host, allowing several conversations to share a single network path. The network layer handles routing and logical addressing between hosts but not per‑process endpoints, while the data link and physical layers manage frames on a single link. So the transport layer is responsible for both end-to-end communication and port multiplexing.

End-to-end communication and port multiplexing are functions of the transport layer. This layer ensures data is delivered between the correct processes on different hosts, handling segmentation, reassembly, flow control, and error checking. It also uses port numbers to distinguish multiple applications on the same host, allowing several conversations to share a single network path. The network layer handles routing and logical addressing between hosts but not per‑process endpoints, while the data link and physical layers manage frames on a single link. So the transport layer is responsible for both end-to-end communication and port multiplexing.