- Computer networking
Computer networking is the
engineering disciplineconcerned with communication between computer systems or devices. Networking, routers, routing protocols, and networking over the public Internethave their specifications defined in documents called RFCs. [ [ftp://ftp.rfc-editor.org/in-notes/bcp/bcp9.txt The Internet Standards Process -- Revision 3] , RFC 2026, S. Bradner, October 1996.] Computer networking is sometimes considered a sub-discipline of telecommunications, computer science, information technologyand/or computer engineering.Computer networks rely heavily upon the theoretical and practical application of these scientific and engineering disciplines.
A computer network is any set of computers or devices connected to each other with the ability to exchange data. [http://www.atis.org/tg2k/_computer_network.html Computer network definition] Examples of different networks are:
Local area network(LAN), which is usually a small network constrained to a small geographic area.
Wide area network(WAN) that is usually a larger network that covers a large geographic area.
*Wireless LANs and WANs (WLAN & WWAN) are the wireless equivalent of the LAN and WAN.
All networks are interconnected to allow communication with a variety of different kinds of media, including twisted-pair copper wire cable,
coaxial cable, optical fiber, and various wireless technologies. [http://www.bellevuelinux.org/network.html Computer networks defined.] The devices can be separated by a few meters (e.g. via Bluetooth) or nearly unlimited distances (e.g. via the interconnections of the Internet[ [http://www.ipnsig.org/reports/ISART9-2000.pdf Interplanetary Internet] , 2000 Third Annual International Symposium on Advanced Radio Technologies, A. Hooke,September 2000] ).
Views of networks
Users and network administrators often have different views of their networks. Often, users share printers and some servers form a workgroup, which usually means they are in the same geographic location and are on the same LAN. A community of interest has less of a connotation of being in a local area, and should be thought of as a set of arbitrarily located users who share a set of servers, and possibly also communicate via
Network administrators see networks from both physical and logical perspectives. The physical perspective involves geographic locations, physical cabling, and the network elements (e.g.,
routers, bridges and application layer gateways that interconnect the physical media. Logical networks, called, in the TCP/IP architecture, subnets , map onto one or more physical media. For example, a common practice in a campus of buildings is to make a set of LAN cables in each building appear to be a common subnet, using virtual LAN (VLAN) technology.
Both users and administrators will be aware, to varying extents, of the trust and scope characteristics of a network. Again using TCP/IP architectural terminology, an intranet is a community of interest under private administration usually by an enterprise, and is only accessible by authorized users (e.g. employees).RFC 2547] Intranets do not have to be connected to the Internet, but generally have a limited connection. An
extranetis an extension of an intranet that allows secure communications to users outside of the intranet (e.g. business partners, customers).
Informally, the Internet is the set of users, enterprises,and content providers that are interconnected by
Internet Service Providers(ISP). From an engineering standpoint, the Internetis the set of subnets, and aggregates of subnets, which share the registered IP addressspace and exchange information about the reachability of those IP addresses using the Border Gateway Protocol. Typically, the human-readablenames of servers are translated to IP addresses, transparently to users, via the directory function of the Domain Name System(DNS).
Over the Internet, there can be business-to-business (B2B), business-to-consumer (B2C) and consumer-to-consumer (C2C) communications. Especially when money or sensitive information is exchanged, the communications are apt to be secured by some form of communications security mechanism. Intranets and extranets can be securely superimposed onto the Internet, without any access by general Internet users, using secure
Virtual Private Network(VPN) technology.
When used for gaming one computer will have to be the server while the others play through it.
Before the advent of computer networks that were based upon some type of
telecommunications system, communication between calculation machines and early computers was performed by human users by carrying instructions between them. Many of the social behavior seen in today's Internet was demonstrably present in nineteenth-century telegraphnetworks, and arguably in even earlier networks using visual signals. [ [http://www.tomstandage.com/vicnet.html "The Victorian Internet"] ,T. Standage,1998]
In September 1940
George Stibitzused a teletype machineto send instructions for a problem set from his Model Kat Dartmouth Collegein New Hampshireto his Complex Number Calculatorin New York and received results back by the same means. Linking output systems like teletypes to computers was an interest at the Advanced Research Projects Agency (ARPA) when, in 1962, J.C.R. Lickliderwas hired and developed a working grouphe called the "Intergalactic Network", a precursor to the ARPANet.
In 1964, researchers at Dartmouth developed the
Dartmouth Time Sharing Systemfor distributed users of large computer systems. The same year, at MIT, a research group supported by General Electricand Bell Labsused a computer (DEC's PDP-8) to route and manage telephone connections.
Throughout the 1960s
Leonard Kleinrock, Paul Baranand Donald Daviesindependently conceptualized and developed network systems which used datagrams or packets that could be used in a packet switched network between computer systems.
1965 Thomas Merrill and Lawrence G. Roberts created the first wide area network(WAN).
The first widely used PSTN switch that used true computer control was the Western Electric
1ESS switch, introduced in 1965.
In 1969 the
University of California at Los Angeles, SRI (in Stanford), University of California at Santa Barbara, and the University of Utahwere connected as the beginning of the ARPANetnetwork using 50 kbit/s circuits. Commercial services using X.25, an alternative architecture to the TCP/IPsuite, were deployed in 1972.
Computer networks, and the technologies needed to connect and communicate through and between them, continue to drive
computer hardware, software, and peripheralsindustries. This expansion is mirrored by growth in the numbers and types of users of networks from the researcher to the home user.
Today, computer networks are the core of modern communication. For example, all modern aspects of the
Public Switched Telephone Network(PSTN) are computer-controlled, and telephonyincreasingly runs over the Internet Protocol, although not necessarily the public Internet. The scope of communication has increased significantly in the past decade and this boom in communications would not have been possible without the progressively advancing computer network.
Networking is a complex part of computing that makes up most of the IT Industry. Without networks, almost all communication in the world would cease to happen. It is because of networking that telephones, televisions, the internet, etc. work.
One way to categorize computer networks is by their geographic scope, although many real-world networks interconnect
Local Area Networks (LAN) via Wide Area Networks (WAN)and wireless networks [WWAN] . These three (broad) types are:
Local area network (LAN)
A local area network is a network that spans a relatively small space and provides services to a small number of people.The first LAN was invented by a Law Doctor in 1978.Fact|date=October 2008 Depending on the number of people that use a Local Area Network, a peer-to-peer or client-server method of networking may be used. A peer-to-peer network is where each client shares their resources with other workstations in the network. Examples of peer-to-peer networks are: Small office networks where resource use is minimal and a home network. A client-server network is where every client is connected to the server and each other. Client-server networks use servers in different capacities. These can be classified into two types: Single-service servers, where the server performs one task such as file server, print server, etc.; while other servers can not only perform in the capacity of file servers and print servers, but they also conduct calculations and use these to provide information to clients (Web/Intranet Server). Computers are linked via Ethernet Cable, can be joined either directly (one computer to another), or via a network hub that allows multiple connections.
Historically, LANs have featured much higher speeds than WANs. This is not necessarily the case when the WAN technology appears as
Metro Ethernet, implemented over optical transmission systems.
Wide area network (WAN)
A wide area network is a network where a wide variety of resources are deployed across a large domestic area or internationally. An example of this is a multinational business that uses a WAN to interconnect their offices in different countries. The largest and best example of a WAN is the
Internet, which is a network comprised of many smaller networks. The Internet is considered the largest network in the world. [http://www.pcmag.com/encyclopedia_term/0,2542,t=internet&j=54184,00.asp "internet" defined] . The PSTN(Public Switched Telephone Network) also is an extremely large network that is converging to use Internet technologies, although not necessarily through the public Internet.
A Wide Area Network involves communication through the use of a wide range of different technologies. These technologies include
Point-to-PointWANs such as Point-to-Point Protocol (PPP) and High-Level Data Link Control ( HDLC), Frame Relay, ATM (Asynchronous Transfer Mode)and Sonet(Synchronous Optical Network). The difference between the WAN technologies is based on the switching capabilities they perform and the speed at which sending and receiving bits of information (data) occur.
Metropolitan Area Network (MAN)
A metropolitan network is a network that is too large for even the largest of LAN's but is not on the scale of a WAN. It also integrates two or more LAN networks over a specific geographical area ( usually a city ) so as to increase the network and the flow of communications. The LAN's in question would usually be connected via "backbone" lines.
Wireless networks (WLAN, WWAN)
A wireless network is basically the same as a LAN or a WAN but there are no wires between hosts and servers. The data is transferred over sets of radio transceivers. These types of networks are beneficial when it is too costly or inconvenient to run the necessary cables. For more information, see
Wireless LANand Wireless wide area network. The media access protocols for LANs come from the IEEE.
The most common
IEEE 802.11WLANs cover, depending on antennas, ranges from hundreds of meters to a few kilometers. For larger areas, either communications satellitesof various types, cellularradio, or wireless local loop ( IEEE 802.16) all have advantages and disadvantages. Depending on the type of mobility needed, the relevant standards may come from the IETFor the ITU.
network topologydefines the way in which computers, printers, and other devices are connected, physically and logically. A network topology describes the layout of the wire and devices as well as the paths used by data transmissions. Commonly used topologies include:
**fully connected (sometimes known as "fully redundant")
The network topologies mentioned above are only a general representation of the kinds of topologies used in computer network and are considered basic topologies.
List of suggested topics for computer networking research.
Andrew S. Tanenbaum, "Computer Networks" (ISBN 0-13-349945-6).
* Important publications in computer networks
Vinton G. Cerf[http://www.cs.washington.edu/homes/lazowska/cra/networks.html "Software: Global Infrastructure for the 21st Century"]
* [http://www.netfilter.org/documentation/HOWTO/networking-concepts-HOWTO.html Easy Network Concepts] (Linux kernel specific)
* [http://nsgn.net/osi_reference_model/ Computer Networks and Protocol] (Research document, 2006)
* [http://compnetworking.about.com/od/basicnetworkingconcepts/l/blglossary.htm Computer Networking Glossary]
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