Reference Models:

      There are two important network architectures. they are ISO-OSI reference model and TCP/IP reference model. These two are discussed below. In 1977, the International Organization for Standardization(ISO) began to develop its OSI networking suite. OSI has two major components an abstract model of networking (the Basic Reference Model, or seven-layer model), and a set of concrete protocols. The standard documents that describe OSI are for sale and not currently available online.
         Parts of OSI have influenced internet protocol development, but none more than the abstract model itself, documented in ISO 7498 and its various addenda. In this model, a networking system is divided into layers. Within each layer, one or more entities implement its functionality. Each entity interacts directly only with the layer immediately beneath it, and provides facilities for use by the layer above it.
        In particular, internet protocols are deliberately not as rigorously architected as the OSI model, but a common version of the TCP/IP model splits it into four layers. The internet Application Layer includes the OSI Application Layer, Presentation Layer, and Session Layer. Its End-to-End Layer includes the graceful close function of the OSI Session Layer as well as the Transport Layer. Its Internet work Layer is equivalent to the OSI Network Layer, while its interface layer includes the OSI Data Link and Physical Layers. These comparisons are based on the original seven-layer protocol model as defined in ISO 7498, rather than refinements in such things as the Internal Organization of the Network Layer document.
       Protocols enable an entity in one host to interact with a corresponding entity at the same layer in a remote host. Service definitions abstractly describe the functionality provided to a (N)-layer by an (N-1) layer, where N is one of the seven layers inside the local host.

                   

OSI :

      In 1977, The international Organization for Standardization (ISO) began to develop its OSI networking suite. OSI has two major components: an abstract model of networking (the basic reference model or seven-layer model), and a set of concrete protocols. 
       OSI have influenced internet protocol development, but non more than the abstract model itself, documented in ISO 7498 and its various addenda. In this model, a networking system is divided into layers.

TCP/IP :

      The TCP/IP model splits it into four layers. This network model currently in internet architecture. It was created in the 1970s by DARPA for use in developing the internet's protocols, and the structure of the internet is still closely reflected by the TCP/IP Model.