Which OSI layer provides end-to-end communication and reliability, commonly using TCP?

Which OSI layer provides end-to-end communication and reliability, commonly using TCP?

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

Answer: (B)

The key idea is end-to-end communication with reliability. The transport layer handles process-to-process communication across the network and is responsible for delivering data reliably from one application to its counterpart. This layer segments data, provides flow control, and ensures reliable delivery through error detection, acknowledgments, and retransmission of lost data. TCP is the protocol most commonly associated with this layer because it offers a connection-oriented service: a connection is established, data is sent in ordered segments with sequence numbers, and any missing pieces are retransmitted to guarantee complete, in-order delivery. In contrast, the network layer focuses on routing and logical addressing, not end-to-end reliability; the data link layer covers node-to-node transfer over a single link; and the application layer deals with network services from the perspective of the end user.

The key idea is end-to-end communication with reliability. The transport layer handles process-to-process communication across the network and is responsible for delivering data reliably from one application to its counterpart. This layer segments data, provides flow control, and ensures reliable delivery through error detection, acknowledgments, and retransmission of lost data. TCP is the protocol most commonly associated with this layer because it offers a connection-oriented service: a connection is established, data is sent in ordered segments with sequence numbers, and any missing pieces are retransmitted to guarantee complete, in-order delivery.

In contrast, the network layer focuses on routing and logical addressing, not end-to-end reliability; the data link layer covers node-to-node transfer over a single link; and the application layer deals with network services from the perspective of the end user.