What is the purpose of the Transport layer in the OSI model?

The purpose of the Transport layer in the OSI model is to facilitate end-to-end communication and ensure reliable data transfer between applications running on different devices. This layer is responsible for delivering messages from the source to the destination while managing error recovery and flow control.

To achieve this, the Transport layer establishes logical connections between the communicating endpoints and may use various protocols, such as TCP (Transmission Control Protocol) for reliable transmission or UDP (User Datagram Protocol) for faster, connectionless communication. This capability ensures that data can be sent and received in the correct sequence, and it allows for retransmission of lost packets, maintaining the integrity of the communication.

The roles of data formatting and encryption are more closely associated with the Presentation layer, while the responsibility for the physical transmission of data packets lies with the Physical layer. Routing data through different networks is a function of the Network layer, which manages how data packets are directed through various network paths. Therefore, the Transport layer’s focus on establishing reliable end-to-end communications with error recovery makes it essential for successful data transmission across the OSI model.