OSI model Diego Abella

Before OSI model Small networks. Small networks. Incompatibilities between devices from different producers. Incompatibilities between devices from different producers. Not global coverage. Not global coverage. High cost. High cost.

OSI model OSI – Open system interconnection. OSI – Open system interconnection. Definition: is an abstract description of how network protocols and equipment interoperate. Definition: is an abstract description of how network protocols and equipment interoperate. International organization of standardization (ISO) – starts with the OSI model in International organization of standardization (ISO) – starts with the OSI model in Ratification in Ratification in 1984.

OSI model layers 7 layers – sequential distribution. Upper layers: Application, presentation and session. Upper layers: Application, presentation and session. Lower layers: Transport, network, data link and physical. Lower layers: Transport, network, data link and physical. The sequence can start in the application or the physical layer

How OSI model works?

OSI model vs. 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 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 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. The OSI model is a very poor standard, but it's the only well-recognized standard we have which describes networked applications. OSI model implements real world protocols. The difficulty with this approach is that there is no general agreement as to which layer of the OSI model to map any specific protocol. OSI model implements real world protocols. The difficulty with this approach is that there is no general agreement as to which layer of the OSI model to map any specific protocol.

TCP/IP model Was created by the U.S. Department of Defence. Was created by the U.S. Department of Defence. Based on simplicity, efficiency and ease of implementation. Based on simplicity, efficiency and ease of implementation. Improves security. Improves security. The TCP/IP model is basically a shorter version of the OSI model. The TCP/IP model is basically a shorter version of the OSI model. Around the world. Around the world.

TCP/IP model  OSI model

OSI model vs. TCP/IP model OSI Model ReferenceTCP/IP Model Reference Service, interface and protocol Service, interface and protocol are not clearly defined. For example, the only real services offered by the Internet layer are - Send IP Packet - Receive IP Packet Protocols in the OSI model are better hidden and can be replaced relatively easily as the technology changes, which is one of the main objectives of layered protocols. Functionalities Functionalities put in each layer are not very optimized. In this case, the models have been prepared for protocols, so the functionalities are perfectly described. Connectionless / Connection- oriented communication Both connectionless and connection-oriented communications are supported in the network layer, but only connection-oriented communication in the transport layer. Only one mode in the network layer (connectionless) but both modes in the transport layer are supported, giving the users a choice.