The Internet

   The Internet is a network of autonomous computer networks that spans the globe. It provides an infrastructure for global electronic information exchange. Today the Internet is used by millions of people of facilitate various activities such as business, education and plain communication.    The Internet grew out of a United States Department of Defense project, the ARPANET (Advanced Research Project Agency Network) started in late 1960s. Its main objective was to provide network links between universities, research organizations and remote computer centers.             The following figure shows how the Internet is structured. At the bottom level are the...

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Network Protocols

           A network protocol is "an agreement on how to converse". The four most commonly used network protocols are TCP/IP, IPX/SPX, X.25 and SNA. Each protocol performs essentially the same functions, but each protocol is incompatible with other unless there is a special device to translate between them. TCP/IP Network Addressing               TCP/IP protocol uses 3 different types of addressing to move data between computers: Physical, Logical and Port addresses. The physical addresses (MAC addresses) are utilized to move data within a single LAN, logical addresses (IP addresses) are used to move data from one LAN to another LAN across the network and the port address...

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Backbone Network Components

         A backbone network is a network that connects many networks in a single site. There are many backbone network components. Router - A router is a special device that enables the connection of two or more networks so that the computers in different networks can communicate with each other. A router may be a special device, a computer with several network interface cards or a special network module in a computer or other network device. Routers also allow a network to be segmented into smaller logical networks or subnets. Bridge - A Bridge is an interface that enables similar networks to communicate. Gateway - A Gateway is an interface that enables dissimilar networks to...

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Data Transmission Types

       In a network data can be transmitted in two different ways, serial transmission and in parallel transmission. Serial Data Transmission - Bits are transmitted sequentially, one after the other. Parallel Data Transmission - Bits are transmitted through separate channels simultaneously.      The standard unit of measure used to specify the speed of the data flow through a network is bits per second (bps). Network Interface Card (NIC)  A network Interface Card provides the physical connection between the computer and a network cable and enables access to a network. Most modern computers come with NIC cards pre-installed, and ready to be connected to networks.  Types...

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Communication Media

           The communication media is the matter or substance that carries the voice or data. Many different types of transmission media are currently in use. All these different media types can be grouped into two categories: Guided media and Radiated media. Guided Media           The guided media are those in which the data flows through physical media. Twisted-pair Wire - A twisted-pair wire consists of two insulated copper wires, twisted around each other and covered in another layer of plastic insulation. Coaxial Cable - A coaxial cable consists of insulated copper wire wrapped in a metal shield, which is then wrapped in an outer external...

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Network Topologies

           Networks can be laid out in a number of different ways. The physical layout of a network is called its topology. The basic network topologies are Star, Ring, Bus. These basic topologies can be combined in a variety of ways to build complex hybrid network topologies. Star Topology            In a star network all computers and other communications devices are connected to a central point such as a hub, file sever or a host computer. Ring Topology             In a ring network all communications devices are connected in a continuous ring. Messages are passed around the ring until...

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Data Communications

           Data Communication is the process of moving information from one point to another by means of some transmission system. Network           A network is a collection of entities that exchange information or good. Few examples of networks are railway system, nervous system of animals, telephone system. Communications Network           A communications network is a system of interconnected computers, and communication devices that can communicate with one another and share resources. At the most elementary level, a computer network consists  of two computers connected with...

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