A computer network or data network is a telecommunications network which allows computers to exchange data. In computer networks, networked computing devices exchange data with each other using a data link. The connections between nodes are established using either cable media or wireless media. The best-known computer network is the Internet.
Network computer devices that originate, route and terminate the data are called network nodes. Nodes can include hosts such as personal computers, phones, servers as well as networking hardware. Two such devices can be said to be networked together when one device is able to exchange information with the other device, whether or not they have a direct connection to each other.
Computer networks differ in the transmission medium used to carry their signals, communications protocols to organize network traffic, the network's size, topology and organizational intent.
Computer networks support an enormous number of applications and services such as access to the World Wide Web, digital video, digital audio, shared use of application and storage servers, printers, and fax machines, and use of email and instant messaging applications as well as many others. In most cases, application-specific communications protocols are layered (i.e. carried as payload) over other more general communications protocols.
Networks are typically managed by the organizations that own them. Private enterprise networks may use a combination of intranets and extranets. They may also provide network access to the Internet, which has no single owner and permits virtually unlimited global connectivity.
The Parts of a Computer Network
Computer networks allow users to connect over distances. They also enable file sharing, hardware sharing and instant communication, making them a convenient tool for the home and a necessity for offices and organizations like universities. A computer network consists of several components, each of which is important to making the network function properly.
COMPUTERS: The purpose of a network is to join computers together. For this to work, the first step in setting up a network is to identify computers and users who may wish to participate in the network. The computers will also need to include software than enables them to connect to the network. Not every computer on the network needs to be running the same operating system. This is true even if users of different types of computers plan to share files, as long es each computer has the appropriate software for opening that file type.
MODEMS: Modems are devices that enable computers to interpret data they receive from a network, and also allow them to send information in the proper format to be read by other computers on the network. The term modem actually means modulator/demodulator, referring to the two jobs the device performs.Modems convert the analog electrical signal that travels over cable, telephone or fiber optic lines into a digital signal that the computer can accept and use to display information to the user. Some modems are built in to computers and others come as external devices.
ROUTERS: Routers, also known as hubs, are another link in the network chain. A router, as its name implies, routes the network signal from the modem to the computer. In some network designs, routers may be unnecessary. But in other instances, such as home and office networks with multiple computers, they are essential.Routers may simply split the signal, allowing several computers to plug in, or may broadcast a wireless signal. Wireless routers broadcast a wifi network that any nearby computers with a wifi antenna can connect to and use. This is why it;s always important to protect such wireless networks with a password to prevent unauthorized network access.
SERVERS: Servers are banks of digital drivers for mass storage of data. Networks use servers to contain the data users may wish to access, and also to provide storage space for network users, For example, on the Internet, email providers use their servers to store the messages users send to one another while web hosts use servers to contain all of the data that a web page displays to visitors.
Intranet
An intranet is a private network accessible only to an organization's staff. Generally a wide range of information and services from the organization's internal IT systems are available that would not be available to the public from the Internet. A company-wide intranet can constitute an important focal point of internal communication and collaboration, and provide a single starting point to access internal and external resources. In its simplest form an intranet is established with the technologies for local area networks (LANs) and wide area networks (WANs).Intranets began to appear in a range of larger organizations from 1994.
Most organizations devote considerable resources into the planning and implementation of their intranet as it is of strategic importance to the organization's success. Some of the planning would include topics such as determining the purpose and goals of the intranet, identifying persons or departments responsible for implementation and management and devising functional plans, page layouts and designs.
The appropriate staff would also ensure that implementation schedules and phase-out of existing systems were organized, while defining and implementing security of the intranet and ensuring it lies within legal boundaries and other constraints. In order to produce a high-value end product, systems planners should determine the level of interactivity (e.g. wikis, on-line forms) desired.
Planners may also consider whether the input of new data and updating of existing data is to be centrally controlled or devolve. These decisions sit alongside to the hardware and software considerations (like content management systems), participation issues (like good taste, harassment, confidentiality), and features to be supported.
Intranets are often static sites; they are a shared drive, serving up centrally stored documents alongside internal articles or communications (often one-way communication). By leveraging firms which specialise in 'social' intranets, organisations are beginning to think of how their intranets can become a 'communication hub' for their entire team. The actual implementation would include steps such as securing senior management support and funding., conducting a business requirement analysis and identifying users' information needs.
From the technical perspective, there would need to be a co-ordinated installation of the web server and user access network, the required user/client applications and the creation of document framework (or template) for the content to be hosted.
The end-user should be involved in testing and promoting use of the company intranet, possibly through a parallel adoption methodology or pilot programme. In the long term, the company should carry out ongoing measurement and evaluation, including through benchmarking against other company services.
Another useful component in an intranet structure might be key personnel committed to maintaining the Intranet and keeping content current. For feedback on the intranet, social networking can be done through a forum for users to indicate what they want and what they do not like.
Extranet
An extranet is a website that allows controlled access to partners, vendors and suppliers or an authorized set of customers – normally to a subset of the information accessible from an organization's intranet. An extranet is similar to a DMZ in that it provides access to needed services for authorised parties, without granting access to an organization's entire network. An extranet is a private network organization.
Historically the term was occasionally also used in the sense of two organizations sharing their internal networks over a VPN.
During the late 1990s and early 2000s, several industries started to use the term 'extranet' to describe centralized repositories of shared data (and supporting applications) made accessible via the web only to authorized members of particular work groups - for example, geographically dispersed, multi-company project teams. Some applications are offered on a software as a service (SaaS) basis.
For example, in the construction industry, project teams may access a project extranet to share drawings, photographs and documents, and use online applications to mark-up and make comments and to manage and report on project-related communications. In 2003 in the United Kingdom, several of the leading vendors formed the Network for Construction Collaboration Technology Providers (NCCTP) to promote the technologies and to establish data exchange standards between the different data systems. The same type of construction-focused technologies have also been developed in the United States, Australia and mainland Europe.
Internetworking
Internetworking is the practice of connecting a computer network with other networks through the use of gateways that provide a common method of routing information packets between the networks. The resulting system of interconnected networks are called an internetwork, or simply an internet. Internetworking is a combination of the words inter ("between") and networking; not internet-working or international-network.
The most notable example of internetworking is the Internet, a network of networks based on many underlying hardware technologies, but unified by an internetworking protocol standard, the Internet Protocol Suite, often also referred to as TCP/IP.
The smallest amount of effort to create an internet (an internetwork, not the Internet), is to have two LANs of computers connected to each other via a router. Simply using either a switch or a hub to connect two local area networks together doesn't imply internetworking; it just expands the original LAN.
Internet
The Internet is the global system of interconnected computer networks that use the Internet protocol suite (TCP/IP) to link devices worldwide. It is a network 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.
The origins of the Internet date back to research commissioned by the United States federal government in the 1960s to build robust, fault-tolerant communication via computer networks. The primary precursor network, the ARPANET, initially served as a backbone for interconnection of regional academic and military networks in the 1980s. The funding of the National Science Foundation Network as a new backbone in the 1980s, as well as private funding for other commercial extensions, led to worldwide participation in the development of new networking technologies, and the merger of many networks. The linking of commercial networks and enterprises by the early 1990s marks the beginning of the transition to the modern Internet, and generated a sustained exponential growth as generations of institutional, personal, and mobile computers were connected to the network. Although the Internet was widely used by academia since the 1980s, the commercialization incorporated its services and technologies into virtually every aspect of modern life.
Internet use grew rapidly in the West from the mid-1990s and from the late 1990s in the developing world. In the 20 years since 1995, Internet use has grown 100-times, measured for the period of one year, to over one third of the world population. Most traditional communications media, including telephony, radio, television, paper mail and newspapers are being reshaped or redefined by the Internet, giving birth to new services such as email, Internet telephony, Internet television music, digital newspapers, and video streaming websites. Newspaper, book, and other print publishing are adapting to website technology, or are reshaped into blogging, web feeds and online news aggregators. The entertainment industry was initially the fastest growing segment on the Internet. The Internet has enabled and accelerated new forms of personal interactions through instant messaging, Internet forums, and social networking. Online shopping has grown exponentially both for major retailers and small businesses and entrepreneurs, as it enables firms to extend their "bricks and mortar" presence to serve a larger market or even sell goods and services entirely online. Business-to-business and financial services on the Internet affect supply chains across entire industries.
The Internet has no centralized governance in either technological implementation or policies for access and usage; each constituent network sets its own policies. Only the overreaching definitions of the two principal name spaces in the Internet, the Internet Protocol address space and the Domain Name System (DNS), are directed by a maintainer organization, the Internet Corporation for Assigned Names and Numbers (ICANN). The technical underpinning and standardization of the core protocols is an activity of the Internet Engineering Task Force (IETF), a non-profit organization of loosely affiliated international participants that anyone may associate with by contributing technical expertise.
refereces
www.techwalla.com/articles/the-parts-of-a-computer-network
www.wikipedia.com/
