Information Technology - Communication And Networks
Information Technology Communication
I.T Communication is simply the processes and techniques known as communication channels that facilitates computers interaction and information sharing.
The concept of data communication evolved from sharing the computation power of a computer along with various resources available in a computer environment such as printers, hard disk and so on. With the increasing demand for exchange of information across the globe, the need for data communication has increased in many folds. Due to physical constraints involved in connecting two remote points, physical data communication has emerged as an instant solution.
A communication channel is a path—transmission medium—over which information travels in a communication system from its source to its destination. Channels are also called links, lines, or media.
1. It uses analog electromagnetic signals representing data to transmit information from one device to another. Electromagnetic signals can travel through a vacuum, air or other transmission media like Wire, fiber optics and soon.
2. It uses a physical medium for transmission (twisted-pair wire, coaxial cable, and Fibre optic cable) is called wired channels. Communication channels that do not require any physical medium for transmission (radio, microwave and communication satellite) are called wireless channels.
3. The basis for all communication channels both wired and wireless is the electromagnetic spectrum. The spectrum covers frequencies for voice, radio waves, infrared light, visible light, and ultraviolet light and X, gamma and cosmic rays.
These communication channels are:
1. Wired Channels
These media are also called guided media since they provide a conduit from one device to another, a signal traveling along any of these media is directed and contained by the physical limits of the medium. Wired communication channels use the following physical media:
A. Twisted-pair wire: Twisted-pair and coaxial cable use metallic (copper) conductors that accept and transport signals in the form of electrical current. The twisted-pair wire is of two types: Unshielded Twisted Pair (UTP) and Shielded Twisted Pair (STP).
B. Coaxial cable: Coaxial cable (simply called coax) has a central core conductor of solid or standard wire (usually copper) enclosed in an insulating sheath, which is, in turn, encased in an outer conductor of metal foil, braid or a combination of the two (also usually copper).
C. Fiber-optic cable: Optical fiber is a glass or plastic cable that accepts and transports signals in the form of light. Let us look more closely at each of the medium. The cable consists of a core made off the new glass or plastic fiber. In most cases, the cladding that effectively traps the light and keeps it bouncing along the central fiber. In most cases, the cladding is covered by a buffer layer that protects it from moisture.
2. Wireless Channels
Wireless Channels transport electromagnetic waves from one point to another through the atmosphere or space without using a physical conductor. The section of electromagnetic spectrum designated for wireless channels called radio spectrum ranges from 3GHz to 300 GHz and is divided into eight bands each regulated by government authorities.
These bands are rated from very low frequency (VLF) to extremely high frequency (EHF). Radio links, microwave links, and satellite communication utilize frequencies in the radio spectrum for data communication.
After connecting computers using some communication channels described above, data needs to be transmitted from one computer to another. Transmission technology is necessarily used to do so. There are two types of transmission technologies:
1. Broadcast networks
2. Point-to-point or Switched networks
Information Technology Networks
I.T Networks is a collection of computers and devices interconnected by communication channels that facilitate communication among users and allows users to share resources.
In human life, people connect and relate to each other for various reasons like friendship, common goals, and common work areas. Whatever the reason may be, these connections form networks of people. Similarly, for computers, although a standalone computer is of great help and assistance when more than one computer is involved as a part of the network, their beneficial value increases enormously.
Computers are networked (physically), through wires or connected without wires. We will have a detailed account of definitions, and concepts related to communication and computer networks in this chapter.
Goals Of Networks
Networks are set up to satisfy certain basic goals. Some of the goals that a network should achieve are:
1. Cost reduction by sharing hardware and software resources
2. Provide high reliability by having multiple sources of supply
3. Provide an efficient means of transport for large volumes of data among various locations.
4. Provide inter-process communication among users and processors
5. Reduction in delay driving data transport
6. Increase productivity by making it easier to share data amongst users
Network Configuration refers to the design of computers within a network to obtain maximum efficiency. There are two types of network configuration:
1. Client-Server Network: Client-Server architecture is one in which the client (personal computer or workstation) is the requesting machine and the server is the supplying machine, both of which are connected via a local area network (LAN) or wide area network (WAN). A client/server network is called a Centralised or Server-based network. The client contains the user interface and may perform some or all of the application processing. Servers can be high-speed microcomputers, minicomputers or even mainframes.
2. Peer to Peer Network: A type of network in which each workstation has equal capabilities and responsibilities is called peer-to-peer networks. Each workstation acts as both a client and a server. There is no central repository for information and there is no central server to maintain.
Types Of Networks
1. Local Area Network: All connected devices in the network share the transmission media. Each device connected in the network can either operate standalone or in the network. The area covered is small, data transfer rates are high, usually, 1Mbps-100Mbps (Million of bits per second), each device connected in the network can communicate with any other device in the network. The cost of setting up the network is usually low.
2. Metropolitan Area Network: Metropolitan Area Network is a computer network designed for a town or city. In terms of geographic area, MAN’s are larger than LANs, but smaller than wide-area networks (WANs). MAN’s are usually characterized by very high-speed connections using fiber optical cable or other digital media.
3. Wide Area Network: Wide Area Network is a computer network that spans a relatively large geographical area. Typically, a WAN consists of two or more local-area networks (LANs). They can connect networks across cities, states or even countries. Computers connected to a wide-area network are often connected through public networks, such as the telephone system. They can also be connected through leased lines or satellites.