The transport layer segments data from the sending host’s system and reassembles the data into a data stream on the receiving host’s system. For example, business users in large corporations often transfer large files from field locations to a corporate site. Reliable delivery of the files is important, so the transport layer breaks down large files into smaller segments that are less likely to incur transmission problems.The boundary between the transport layer and the session layer can be thought of as the boundary between application protocols and data-flow protocols.
Whereas the application, presentation, and session layers are concerned with application issues, the lower four layers are concerned with data-transport issues. The transport layer attempts to provide a data-transport service that shields the upper layers from transport implementation details. Specifically, issues such as reliability of transport between two hosts are the concern of the transport layer. In providing communication service, the transport layer establishes, maintains, and properly terminates virtual circuits. Transport error detection and recovery and information flow control provide reliable service.
Whereas the application, presentation, and session layers are concerned with application issues, the lower four layers are concerned with data-transport issues. The transport layer attempts to provide a data-transport service that shields the upper layers from transport implementation details. Specifically, issues such as reliability of transport between two hosts are the concern of the transport layer. In providing communication service, the transport layer establishes, maintains, and properly terminates virtual circuits. Transport error detection and recovery and information flow control provide reliable service.
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