OSI Layer Reference Model

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International Organization for Standardization makes Open System Interconnection (OSI) reference model as solution to solve incompatible connection between network interfaces. The OSI reference model is a layered, abstract representation created as a guideline for network protocol design.

The OSI model divides the networking process into seven logical layers, each of which has unique functionality and to which are assigned specific service and protocols. In this model, information is passed from one layer to the next, starting at the Application layer on the transmitting host, and proceeding down the hierarchy to Physical layer, then passing over the communications channel to destination host, where the information proceeds back up the hierarchy, ending at the Application layer.

Here is seven layer of OSI:

Layer 7, Application: This layer enable human network to interface with the underlying data network, example when use Mozilla for browsing, that’s show operation at application layer.

Layer 6, Presentation: This layer has primary functions about coding, compression and encryption, example MPEG is standard video compression and coding, GIF and JEPG are compression and coding standard for graphic image.

Layer 5, Session: function of this layer is to create and maintain dialog between source and destination about called session. Example initiate dialogs, start, keep alive, restart or stop conversation.

Layer 4, Transport: this layer provides for the segmentation of data and reassembles back into complete data. TCP and UDP is common protocol on this layer. Emphasizing in port addressing, error recovery, and flow control.

Layer 3, Network: this layer function is to provide service to exchange data between network devices. This layer use IP addressing, encapsulation, routing and decapsulation process.

Layer 2, Data Link: this layer function is to prepare Network layer packets for transmission and control access to physical media, commonly about MAC addressing and switches.

Layer 1, Physical: this layer function is to encode the binary digits that represent Data Link layer and to transmit and receive this signal across the physical media like copper wires, optical fiber, and wireless.

Hope after knowing OSI layer reference model will make us comfort with computer networking and internet.

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