Data Processing Notes

Computer Networking


Networking is the practice of linking two or more computing devices together for the purpose of sharing data. Networks are built with a mix of computer hardware and computer software.

Network Design

Computer networks also differ in their design. The two basic forms of network design are called client/server and peer-to-peer. Client-server networks feature centralized server computers that store email, Web pages, files and or applications.

A Network Topology

A network topology represents its layout or structure from the point of view of data flow.

Network Protocols

Communication languages used by computer devices are called network protocol. Yet another way to classify computer networks is by the set of protocols they support. Networks often implement multiple protocols with each supporting specific applications. Popular protocols include TCP/IP, the most common protocol found on the Internet and in home networks.

The Internet

The Internet is the global system of interconnected computer networksthat use the Internet protocol suite (TCP/IP) to link devices worldwide. It is anetwork of networks that consists of private, public, academic, business, and government networks of local to global scope, linked by a broad array of electronic, wireless, and optical networking technologies. The Internet carries an extensive range of information resources and services, such as the inter-linked hypertext documents and applications of the World Wide Web(WWW), electronic mail, telephony, and peer-to-peer networks for file sharing.

An intranet

An intranet is a private network that is contained within an enterprise. It may consist of many interlinked local area networks and also use leased lines in the wide area network. Typically, an intranet includes connections through one or more gateway computers to the outside Internet. The main purpose of an intranet is to share company information and computing resources among employees. An intranet can also be used to facilitate working in groups and for teleconferences.

An extranet

An extranet is a private network that uses Internet technology and the public telecommunication system to securely share part of a business‘s information or operations with suppliers, vendors, partners, customers, or other businesses. An extranet can be viewed as part of a company’s intranet that is extended to users outside the company. It has also been described as a “state of mind” in which the Internet is perceived as a way to do business with other companies as well as to sell products to customers.

A personal area network-PAN

Definition: A personal area network-PAN- is a computer network organized around an individual person. Personal area networks typically involve a mobile computer, a cell phone and/or a handheld computing device such as a PDA. You can use these networks to transfer files including email and calendar appointments, digital photos and music.

Local area network

A local area network (LAN) is a network that connects computers and devices in a limited geographical area such as home, school, computer laboratory, office building, or closely positioned group of buildings. Each computer or device on the network is a node.

Metropolitan area network

A Metropolitan area network (MAN) is a large computer network that usually spans a city or a large campus.

Wide area network

A wide area network (WAN) is a computer network that covers a large geographic area such as a city, country, or spans even intercontinental distances, using a communications channel that combines many types of media such as telephone lines, cables, and air waves. A WAN often uses transmission facilities provided by common carriers, such as telephone companies.

Client-Server Network

Aclient-server networkis designed for end-users, calledclients, to access resources such as files, songs, video collections, or some other service from a central computer called a server.

A Peer-To-Peer (P2p) Network

In its simplest form, a peer-to-peer (P2P) network is created when two or more PCs are connected and share resources without going through a separate server computer. A P2P network can be an ad hoc connection—a couple of computers connected via a Universal Serial Bus to transfer files.

Network Topology

A network topology is the pattern in which nodes(i.e., computers, printers, routers or other devices) are connected to a local area network(LAN) or other network via links (e.g., twisted paircopper wire cable or optical fiber cable).

There are four principal topologies used in LANs: bus, ring, star and mesh. The most widely used of these is bus, because it is employed by Ethernet, which is the dominant LAN architecture. In a bus topology all devices are connected to a central cable, called the  bus or backbone. This topology is relatively inexpensive and easy to install for small networks.

In a ring topology each device is connected directly to two other devices, one on either side of it, to form a closed loop. This topology is relatively expensive and difficult to install, but it offers high bandwidth and can span large distances. A variation is the token ring, in which signals travel in only one direction around the loop, carried by a so-called token from node to node.

In a star topology all devices are connected directly to a central computer or server. Such networks are relatively easy to install and manage, but bottlenecks can occur because all data must pass through the central device.

The mesh topology can be either a full mesh or a partial mesh. In the former, each computer is connected directly to each of the others. In the latter, some computers are connected to most of the others, and some are connected only to those other nodes with which they exchange the most data.

The several basic network topologies can be combined in various ways to form hybrid topologies, such as a ring-star network or a tree network. The latter consists of two or more star networks connected to a linear bus.

The word topology comes from the Greek words topos meaning place and logos meaning study. It is a description of any locality in terms of its layout. Topology is a branch of mathematics concerned with properties of geometric figures that are distorted without tearing or bonding together.

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