kdarider.blogg.se

Common application service element (CASE) provides services for the application layer and requests services from the session layer.The application layer was developed with two sublayers: This layer facilitates the communication with applications running on other computers. The presentation layer supports message formatting and encryption. The session layer manages all phases of a session, including setup, in-process control functions and message takedown, and supports concurrent transmission of multiple bidirectional messages. The transport layer facilitates error recovery and reorders data packets that are in the wrong sequence. The network layer determines how messages move across a network, such as end-to-end movement of data packets using logical addresses. The data link layer defines how data is transferred over a connecting link. In the physical layer, devices such as a local area network or router physically link to a network. OSI layers and their functions in a communications network