Computer Networks Overview

The term networks (communication networks) generally refers to systems hardware, software and services / opportunities, aimed at transmission and routing data and to transfer information between electronic / channels (such as various types of computers, terminals, telephones) .

The term includes the various technologies

• telecommunications networks
• computer networks (local (LANs), Metropolitan (MANs), wide area (WANs) and Websites)
• integrated services digital networks close (N-ISDN) and large B-ISDN) zone, and all wireless communication technologies.

For the classification of networks can be used several characteristics:

The architecture and techniques used for transporting data, which are:

• Switching circuit package, frame, cell
• Broadcast networks.

The geographical coverage offered

• Data flow machines and multiprocessor systems
• Local Computer Networks [Local Area Networks]
• Metropolitan Area Networks
• Regional Area Networks
• Wide Area Networks
• Interconnection of long haul networks or Global Area Networks

The bandwidth offered (bandwidth)

The type of applications supported

The regulatory framework for the operation

The used hardware and software, etc.

Both the technology and the different standards, leading to a single communication system, which will consolidate all communications patterns, which will provide broad geographic coverage, and seamless and easy access to all sources of information. It is clear that a basic condition for achieving these objectives is the existence of a modern telecommunications infrastructure polydynamics. The infrastructure should provide the widest possible geographical coverage, to provide a basic standard set of advanced services with high added value and have the prospect of switching to high-speed networks (2 Mbps to 622.5 Mbps.)

Technoeconomical key factors of development of each communication technology, but also functional integration of individual infrastructure is a mature and widely accepted standard, which refer to protocols (ie, a set of rules and conditions which determine the communication) a specific architecture (Reference Model ).  The most famous architecture is that of seven levels, which is described as Reference Model Open Systems Interface (OSIRM-Open Systems Interconnect Reference Model).
 Despite the fact that the OSI model has contributed greatly to the broad dissemination of the concepts of protocols in layers and that is an extremely useful tool for presentation and comparative study of various technologies, the same protocols OSI does not have the broad dissemination of other similar architectures (DoD example of architecture with plenty of protocols TCP / IP).

The technical description followed the model OSI, is that architecture in layers / levels (layered architecture). Each open system divided logically arranged in a set of subsystems and communications functions are shared in a sharply ordered all epipedon. Basic functions that are common at all levels are:

Encapsulation (Encapsulation)

Segmentation (Segmentation)

Installation Association (Connection Establishment)

Flow Control (Flow Control)

Error Control (Error Control)

Polyplexia (Multiplexing)

Transfer Means

• Twisted Pair
• Baseband Coaxial Cable
• Broadband Coaxial Cable
• Fiber Optics