OSI Model: Using Open Systems Interconnection to Send and Receive Data

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• published: 23 Jun 2016
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OSI Model: Using Open Systems Interconnection to Send and Receive Data Instructor: Jill Heaney Jill has taught college-level business and IT. She has a Doctorate in Business Administration and an M.S. in Information Technology & Leadership. The Open System Interconnection (OSI) model describes how data is sent and received over a network. It consists of seven layers: the physical layer, data link layer, network layer, transport layer, session layer, presentation layer, and application layer. This lesson discusses how the OSI model works and the role of each layer for transmitting messages. Open Systems Interconnection (OSI) Model The Open Systems Interconnection (OSI) model is a suggested standard for communication that was developed by the International Organization for Standardization (ISO). The OSI reference model describes howdata is sent and received over a network. This model breaks down data transmission over a series of seven layers. Each layer has a responsibility to perform specific tasks concerning sending and receiving data. All of the layers are needed for a message to reach its destination. The OSI model gives software developers a standard for developing communication software. The OSI model provides the standard for communication so that different manufacturers' computers can be used on the same network. The Seven Layers of the OSI Model These layers are the physical layer, data link layer, network layer, transport layer, session layer, presentation layer, and application layer. Software and hardware can then be developed for each layer separately. However, they must work together to successfully transport a message. Each layer performs a specific function, but all of the layers have one function in common: communicating with the layers above and below them in the model. The application layer is the software that the end user interacts with. This is an application like Firefox, Outlook, or Internet Explorer. This layer provides service to applications outside of the OSI model. It performs several functions, including establishing the availability of the communication partner, synchronizing the sending and receiving of applications, establishing agreement on error recovery and data integrity, and determining if sufficient resources exist for the communication to occur. The presentation layer is concerned with the presentation of data. This layer defines the format the data uses as it is transmitted. It formats the data for the user so that it is readable and the message can be understood. This layer may also compress data for easier transmission or encrypt data for security purposes. The session layer is responsible for allowing ongoing communication between two parties across the network. It handles the setup of the session, data exchanges, and the end of the session. This layer is responsible forflow control, or defining the rules for communication between two computers. Flow control will prevent too much data from being sent to the receiving computer at one time so it does not become overloaded.