Thursday, June 18, 2009

The OSI Model:

Open System Interconnection (OSI) reference model has become an International standard and serves as a guide for networking. This model is the best known and most widely used guide to describe networking environments. Vendors design network products based on the specifications of the OSI model. It provides a description of how network hardware and software work together in a layered fashion to make communications possible. It also helps with trouble shooting by providing a frame of reference that describes how components are supposed to function.

There are seven to get familiar with and these are the physical layer, data link layer, network layer, transport layer, session layer, presentation layer, and the application layer.

* Physical Layer, is just that the physical parts of the network such as wires, cables, and there media along with the length. Also this layer takes note of the electrical signals that transmit data throughout system.
* Data Link Layer, this layer is where we actually assign meaning to the electrical signals in the network. The layer also determines the size and format of data sent to printers, and other devices. Also I don’t want to forget that these are also called nodes in the network. Another thing to consider in this layer is will also allow and define the error detection and correction schemes that insure data was sent and received.
* Network Layer, this layer provides the definition for the connection of two dissimilar networks.
* Transport Layer, this layer allows data to be broken into smaller packages for data to be distributed and addressed to other nodes (workstations).
* Session Layer, this layer helps out with the task to carry information from one node (workstation) to another node (workstation). A session has to be made before we can transport information to another computer.
* Presentation Layer, this layer is responsible to code and decode data sent to the node.
* Application Layer, this layer allows you to use an application that will communicate with say the operation system of a server. A good example would be using your web browser to interact with the operating system on a server such as Windows NT, which in turn gets the data you requested.

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