telecomunications networks

telecomunications networks - NETWORKING Functions of...

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NETWORKING Functions of Telecommunications Networks Name here Professor David G. Moore CSI-106 May 16 th 2014
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NETWORKING 1) Telecommunications networks Electronic system of links and switches, and the controls that govern their operation, that allows for data transfer and exchange among multiple users. When several users of telecommunications media wish to communicate with one another, they must be organized into some form of network. In theory, each user can be given a direct point-to-point link to all the other users in what is known as a fully connected topology (similar to the connections employed in the earliest days of telephony), but in practice this technique is impractical and expensive— especially for a large and dispersed network. Furthermore, the method is inefficient, since most of the links will be idle at any given time. Modern telecommunications networks avoid these issues by establishing a linked network of switches, or nodes, such that each user is connected to one of the nodes. Each link in such a network is called a communications channel. Wire, fiber- optic cable, and radio waves may be used for different communications channels. Different communication requirements necessitate different network solutions, and these different network protocols can create significant problems of compatibility when networks are interconnected with one another. In order to overcome some of these interconnection problems, the International Organization approved the open systems interconnection (OSI) in 1983 as an international standard for communications architecture for Standardization (ISO) and the International Telegraph and Telephone Consultative Committee (CCITT). The OSI model consists of seven layers, each of which is selected to perform a well-defined function at a different level of abstraction. The bottom three layers provide for the timely and correct transfer of data, and the top four ensure that arriving data are recognizable and useful. While all seven
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NETWORKING layers are usually necessary at each user location, only the bottom three is normally employed at a network node, since nodes are concerned only with timely and correct data transfer from point to point. Data recognition and use The application layer is difficult to generalize, since its content is specific to each user. For example, distributed databases used in the banking and airline industries require several access and security issues to be solved at this level. Network transparency (making the physical distribution of resources irrelevant to the human user) also is handled at this level. The presentation layer, on the other hand, performs functions that are requested sufficiently often that a general solution is warranted. Several users running different applications will often place these functions in a software library that is accessible. Examples are text conversion, data compression, and data encryption.
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  • Spring '14
  • moore
  • Computer network, Local area network, UTP cable

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