User talk:Osk1982

OSI Reference Model: The OSI Model is a theoretical, seven-layered model of how networks work. The Open Systems Interconnect (OSI) Model is a theoretical model of networking that organizes network functions into seven layers (Physical Layer, Data Link Layer, Network Layer, Transport Layer, Session Layer, Presentation Layer and Application Layer) and specifies the communication interfaces between the OSI Model's layers and between network endpoints utilizing an OSI Model-based protocol suite. The short form used to memorize the layer names of the OSI Model is “All People Seem To Need Data Processing”. Functions of each layer of the OSI Model: 1. Application Layer: The Application Layer of the OSI model is responsible for providing end-user services, such as file transfers, electronic messaging, e-mail, virtual terminal access, and network management. This is the layer with which the user interacts. 2. Presentation Layer: The Presentation Layer of the OSI model is responsible for defining the syntax which two network hosts use to communicate. Encryption and compression should be Presentation Layer functions. 3. Session Layer: The Session Layer of the OSI model is responsible for establishing process-to-process communications between networked hosts. 4. Transport Layer: The Transport Layer of the OSI model is responsible for delivering messages between networked hosts. The Transport Layer should be responsible for fragmentation and reassembly. 5. Network Layer: The Network Layer of the OSI model is responsible for establishing paths for data transfer through the network. Routers operate at the Network Layer. 6. Data Link Layer: The Data Link Layer of the OSI model is responsible for communications between adjacent network nodes. Hubs and switches operate at the Data Link Layer. 7. Physical Layer: The Physical Layer of the OSI model is responsible for bit-level transmission between network nodes. The Physical Layer defines items such as: connector types, cable types, voltages, and pin-outs. The OSI Model Vs the Real World: The most major difficulty with the OSI model is that is does not map well to the real world..! The OSI was created after many of today’s protocols were already in production use. These existing protocols, such as TCP/IP, were designed and built around the needs of real users with real problems to solve. The OSI model was created by academicians for academic purposes. The OSI model is a very poor standard, but it’s the only well-recognized standard we have which describes networked applications.