in the late 1970S, the Open System Interconection (OSI) referenced model was created by International Organization for Standardization (ISO) to break networking of an computer that could tipically comunicate only with computers from the same manufacture.
The Open System Interconnection (OSI) Model is a the primary architectural model for networks. It describe how data and networks information are communicated from application on another application on one computer through the network media to an application on another computer.
The advantages of using the OSI layer model:
- It divides the network communication process into smaller and simpler components, thus aiding component development, design and troubelshooting.
- It allows multiple-vendor development through standardization of networks components.
- It encourages industry standardization by defining what functions occur at each layer of the model
- It allow various types of networks hardware and software to communicate.
- It prevents changes in one layer from affecting other layer, so it does nit hamper development
One of the best functions of the OSI specifications is to assist in data transfer between disparate hosts / vendor. The OSI isn't a physical model, but it's a set of guidelines that application developers can use to create and implement applications that run on a network. It also provides a framework for creating and implementing networking standards, devices, and internetworking schemes.
The Open Systems Interconnection (OSI) model has seven different layers, and divide into two groups:
- The top three layer (upper layer) 'define how' the application within the end stations will communicate with each other and with user. so, upper layer is responsible for application communicating between hosts. none of upper layer knows anything about networking of network address.
- The bottom four layer (bottom layer) 'define how' data is transmitted end to end, how data is transferred through a physical wire or through switches and routers. The bottom layers also determine how to rebuild a data stream from a transmitting host to a destination host's application.
- Network management stations (NMSs)
- Web and application servers
- Gateway (not default gateways)
- Networks host
- Application layer (layer 7)
- Presentation layer (layer 6)
- Session layer (layer 5)
- Transport layer (layer 4)
- Network layer (layer 3)
- Data link layer (layer 2)
- physical layer (layer 1)
glossary review :
- network: multiple computers connected together using a communications system.
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