OSI (Open System Interconnection), Open Systems Interconnection Reference Model. Is a logical definition, a specification that the network protocol into a layer 7 from the logic. Each layer has an associated, corresponding to a physical device, such as a conventional three-switching device is a router, the conventional switches are of switching devices. OSI seven-layer model is a framework of design methods, the main purpose is to establish a seven-layer model to solve the compatibility problem encountered when heterogeneous network interconnection, its main function is to help different types of host data transfer . Its biggest advantage is to distinguish between services, interfaces and protocols clearly distinguish these three concepts, reliable communications through seven levels of structural models of the different systems between different networks.
TCP / IP Internet protocol is a basic agreement, basic Internet Internet, mainly by the TCP transport layer protocol IP protocol and network layers. TCP / IP defines how an electronic device connected to the Internet, and how the standard data transfer therebetween. Protocol uses a hierarchical structure of four layers, each layer protocol call its lower layer provided to complete their needs.
ISO developed the OSI reference model is too large, complex lead to a lot of criticism. With the popularity of the Internet, TCP / IP protocol stack itself used to obtain a more widely used and recognized. In the TCP / IP reference model, removing the session and presentation layers (two layers functions are incorporated into the application layer) of the OSI reference model. While the OSI reference model data link layer and the physical layer to the network layer merged into a host.