The Open Systems Interconnection (OSI) model is a reference tool for understanding data communications between any two networked systems. It divides the communications processes into seven layers. Each layer both performs specific functions to support the layers above it and offers services to the layers below it. The three lowest layers focus on passing traffic through the network to an end system. The top four layers come into play in the end system to complete the process. | Global Knowledge Expert Reference Series ofWhite Papers The OSI Model Understanding the Seven Layers of Computer Networks 1-800-COURSES The OSI Model Understanding the Seven Layers of Computer Networks Paul Simoneau Global Knowledge Course Director Network CCNA CTP Introduction The Open Systems Interconnection OSI model is a reference tool for understanding data communications between any two networked systems. It divides the communications processes into seven layers. Each layer both performs specific functions to support the layers above it and offers services to the layers below it. The three lowest layers focus on passing traffic through the network to an end system. The top four layers come into play in the end system to complete the process. This white paper will provide you with an understanding of each of the seven layers including their functions and their relationships to each other. This will provide you with an overview of the network process which can then act as a framework for understanding the details of computer networking. Since the discussion of networking often includes talk of extra layers this paper will address these unofficial layers as well. Finally this paper will draw comparisons between the theoretical OSI model and the functional TCP IP model. Although TCP IP has been used for network communications before the adoption of the OSI model it supports the same functions and features in a differently layered arrangement. An Overview of the OSI Model Networking OSI seven-layer model Chaos Checking networking Applications Without the OSI model networks would be very difficult to understand and implement. 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data link With the OSI model networks can be broken up into manageable pieces. The OSI model provides a common language to explain components and their functionality. Mostly software t I Mostly hardware Copyright 2006 Global Knowledge Training LLC. All .
