What is Networking

A computer network consists of two or more computers, and typically other devices as well (such as printers, external hard drives, modems and routers), that are linked together so that they can communicate with each other and thereby exchange commands and share data, hardware and other resources.

The devices on a network are referred to as nodes. Nodes can be connected using any of various types of media, including twisted pair copper wire cable, optical fiber cable, coaxial cable and radio waves. And they can be arranged according to several basic topologies. A network topology represents its layout or structure from the point of view of data flow. Typical topologies include bus (in which all nodes are connected along a single cable), star (all nodes are connected to a central node), tree (nodes successively branch off from other nodes) and ring.

The smallest and simplest networks are local area networks (LANs), which extend over only a small area, typically within a single building or a part thereof. A home network is a type of LAN that is contained within a user's residence. Wide area networks (WANs) can extend over a large geographic area and are connected via the telephone network or radio waves. A metropolitan area network (MAN) is designed to serve a town or city, and a campus area network is designed to serve a university or other educational institution.

Many of the same network protocols, like TCP/IP, work in both wired and wireless networks. Wired Networks with Ethernet cables predominated in businesses, schools, and homes for several decades. Ethernet is a physical and data link layer technology for local area networks (LANs). When first widely deployed in the 1980s, Ethernet supported a maximum theoretical data rate of 10 megabits per second (Mbps). Later, Fast Ethernet standards increased this maximum data rate to 100 Mbps. Today, Gigabit Ethernet technology further extends peak performance up to 1000 Mbps. The run length of individual Ethernet cables is limited to roughly 100 meters, but Ethernet can be easily extended to link entire schools or office buildings using network bridge devices.

Wireless networks utilize radio waves and/or microwaves to maintain communication channels between computers. A wireless network offers advantages and disadvantages compared to a wired network. Advantages of wireless include mobility and elimination of unsightly cables. Disadvantages of wireless include the potential for radio interference due to weather, other wireless devices, or obstructions like walls. Popular wireless local area networking (WLAN) products clonform to the 802.11 "Wi-Fi" standards. 802.11b WLANs offer maximum theoretical bandwidth of 11 Mbps. 802.11a and 802.11g WLANs offer theoretical bandwidth up to 54 Mbps. The performance of Wi-Fi networks in practice never approaches the theoretical maximum. 802.11b networks, for example, generally operate no faster than about 50% of theoretical peak, or 5.5 Mbps. Likewise, 802.11a and 802.11g networks generally run no faster than 20 Mbps. The disparity between theoretical and practical performance comes from protocol overhead, signal interference, and decreasing signal distance with distance. In addition, the more devices communicating on a WLAN simultaneously, the slower the network will appear. On home networks, keep in mind that the performance of an Internet connection is often the limiting factor in network speed. Even though files can be shared on a wireless LAN at speeds of 5 or 20 Mbps, wireless clients will still connect to the Internet at the speed typically offered by Internet Service Providers, usually less than 1 Mbps.

Security is a major concern when building either a wired or wireless network. Unfortunately, no computer network is truly secure. It's always theoretically possible for eavesdroppers to view or "snoop" the traffic on any network, and it's often possible to add or "inject" unwelcome traffic as well. Wireless networks add an extra level of security complexity compared to wired networks. Whereas wired networks send electrical signals or pulses of light through cable, wireless radio signals propogate through the air and are naturally easier to intercept. Signals from most wireless LANs (WLANs) pass through exterior walls and into nearby streets or parking lots. The practice of wardriving, for example, exposed the vulnerabilities of home WLANs and accelerated the pace of security technology advances in home wireless equipment. Security features like 128-bit WEP and WPA can scramble or "encrypt" network traffic so that its contents can not easily be deciphered by snoopers. Likewise, wireless routers and access points (APs) incorporate access control features such as MAC address filtering that deny network requests from unwanted clients.

Computer networks also differ in their design. The two types of high-level network design are called client-server and peer-to-peer. In a client-server network design, client devices are typically PCs with network software applications installed that request and receive information over the network. Mobile devices as well as desktop computers can both function as clients. A server device typically stores files and databases including more complex applications like Web sites. Server devices often feature higher-powered central processors, more memory, and larger disk drives than clients. Computers in a peer to peer network run the same networking protocols and software. Peer networks are also often situated physically near to each other, typically in homes, small businesses or schools. Home networks that utilize broadband routers are hybrid peer to peer and client-server environments. The router provides centralized Internet connection sharing, but file, printer and other resource sharing is managed directly between the local computers involved.

An intranet is a private network within an organization that uses the same communications protocols as the Internet. When part of an intranet is made accessible to suppliers, customers or others outside the organization, that part becomes an extranet. This is accomplished by configuring a VPN - Virtual Private Network. A VPN is configured in the Front Ened/Firewall/Router by identifying specific IP address and creating a "Trust" relationship on the Domain Server.

An internet (spelled with a lower case i) is a network that is composed of a number of smaller computer networks. The Internet (spelled with an upper case I) is the world-wide network of interconnected internets that operates using a standardized set of communications protocols called TCP/IP (transmission control protocol/Internet protocol), or the Internet protocol suite. This ultimate internet is vastly larger than any other internet and connects thousands of networks and hundreds of millions of computers throughout the world.

A protocol defines a common set of rules and signals that computers on the network use to communicate. TCP/IP is not only the protocol of the Internet, but it has also become the dominant protocol for computer networks of virtually all types. Originally developed for use in UNIX, TCP/IP is now built into virtually all major computer operating systems. Reasons for its success, and thus for the astonishing success of computer networks in general, include the facts that it is intelligent, robust, compatible with nearly all types of hardware and operating systems, relatively simple and free software (which means that it free with regard to both cost and use).

Computers were originally stand-alone systems that consisted of a mainframe that was connected to a number of input and output devices (mainly keyboards, punched card reading/punching machines and printers). The ability for multiple computers to be connected over long distances began in 1969 at the University of California at Los Angeles (UCLA) with the development of ARPANET. Originally developed by DARPA, the Defense Advanced Research Projects Agency, it was created as a means to share information on defense research between involved universities and defense research facilities. Originally it was just email and FTP sites as well as the Usenet where scientists could question and answer each other and it was called ARPANET (Advanced Research Projects Agency NETwork). The concept was developed starting in 1964, and the first messages passed were between UCLA and the Stanford Research Institute in 1969. Leonard Kleinrock of MIT had published the first paper on packet switching theory in 1961. Since networking computers was new to begin with, standards were being developed on the fly. Once the concept was proven, the organizations involved started to lay out some ground rules for standardization. UCLA also took a key step in the development of this standardization by establishing the Request for Comments (or RFC) series of notes. One of the most important RFCs was the communications protocol, TCP/IP, developed by Vint Cerf and Robert Kahn in 1974. This created the concept of open sourcing allowing usinversities and corporations to collaboratively create the internet as it is known today.

For more on the history of the internet visit: Brief history of the internet

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