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Encyclopedia > Wide area network

Wide Area Network (WAN) is a computer network that covers a broad area (i.e., any network whose communications links cross metropolitan, regional, or national boundaries [1]). Or, less formally, a network that uses routers and public communications links [1]. Contrast with personal area networks (PANs), local area networks (LANs), campus area networks (CANs), or metropolitan area networks (MANs) which are usually limited to a room, building, campus or specific metropolitan area (e.g., a city) respectively. The largest and most well-known example of a WAN is the Internet. Computer networks may be classified according to the network layer at which they operate according to some basic reference models that are considered to be standards in the industry such as the seven layer OSI reference model and the four layer Internet Protocol Suite model. ... The term communications is used in a number of disciplines: Communications, also known as communication studies is the academic discipline which studies communication, generally seen as a mixture between media studies and linguistics. ... In telecommunications a link is the communications channel that connects two or more communicating devices. ... A personal area network (PAN) is a computer network used for communication among computer devices (including telephones and personal digital assistants) close to one person. ... “LAN” redirects here. ... In the case of a university campus-based campus area network the network is likely to link a variety of campus buildings including academic departments, the university library and student residence halls. ... Metropolitan area networks, or MANs, are large computer networks usually spanning a city. ...


WANs are used to connect LANs and other types of networks together, so that users and computers in one location can communicate with users and computers in other locations. Many WANs are built for one particular organization and are private. Others, built by Internet service providers, provide connections from an organization's LAN to the Internet. WANs are often built using leased lines. At each end of the leased line, a router connects to the LAN on one side and a hub within the WAN on the other. Leased lines can be very expensive. Instead of using leased lines, WANs can also be built using less costly circuit switching or packet switching methods. Network protocols including TCP/IP deliver transport and addressing functions. Protocols including Packet over SONET/SDH, MPLS, ATM and Frame relay are often used by service providers to deliver the links that are used in WANs. X.25 was an important early WANSACHMO protocol, and is often considered to be the "grandfather" of Frame Relay as many of the underlying protocols and functions of X.25 are still in use today (with upgrades) by Frame Relay. “ISP” redirects here. ... A leased line is a symmetric telecommunications line connecting two locations together. ... This article is about a computer networking device. ... In telecommunications, a circuit switching network is one that establishes a dedicated circuit (or channel) between nodes and terminals before the users may communicate. ... In computer networking and telecommunications, packet switching is a communications paradigm in which packets (messages or fragments of messages) are individually routed between nodes, with no previously established communication path. ... This article concerns communication between pairs of electronic devices. ... The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet runs. ... Packet over SONET/SDH, abbreviated POS, is communications protocol for transmitting packets over SDH or SONET, which are both circuit switched protocols. ... In computer networking and telecommunications, Multi Protocol Label Switching (MPLS) is a data-carrying mechanism that belongs to the family of packet-switched networks. ... Asynchronous Transfer Mode (ATM) is a cell relay, packet switching network and data link layer protocol which encodes data traffic into small (53 bytes; 48 bytes of data and 5 bytes of header information) fixed-sized cells. ... In the context of computer networking, frame relay consists of an efficient data transmission technique used to send digital information quickly and cheaply in a relay of frames to one or many destinations from one or many end-points. ... X.25 is an ITU-T standard protocol suite for wide area networks using leased lines, the phone or ISDN system as the networking hardware. ... X.25 is an ITU-T standard protocol suite for wide area networks using leased lines, the phone or ISDN system as the networking hardware. ...


Academic research into wide area networks can be broken down into three areas: Mathematical models, network emulation and network simulation. A mathematical model is an abstract model that uses mathematical language to describe the behaviour of a system. ... Network emulation is a technique where the properties of a non-ideal network are simulated. ... In computer network research, network simulation is a technique where a program simulates the behavior of a network. ...


Performance improvements are sometimes delivered via WAFS or WAN Optimization. Wide Area File Services (WAFS) products allow remote office users to access and share files globally at LAN speeds over the WAN. Distributed enterprises that deploy WAFS solutions are able to consolidate storage to corporate datacenters, eliminating the need to backup and manage data that previously resided in their remote... WAN optimization products seek to accelerate a broad range of applications accessed by distributed enterprise users via eliminating redundant transmissions, staging data in local caches, compressing and prioritizing data, and streamlining chatty protocols (e. ...

Contents

WAN connectivity options

Several options are available for WAN connectivity: [2]

Option: Description Advantages Disadvantages Bandwidth range Sample protocols used
Leased line Point-to-Point connection between two computers or Local Area Networks (LANs) Most secure Expensive PPP, HDLC, SDLC, HNAS
Circuit switching A dedicated circuit path is created between end points. Best example is dialup connections Less Expensive Call Setup 28 Kb/s - 144 Kb/s PPP, ISDN
Packet switching Devices transport packets via a shared single point-to-point or point-to-multipoint link across a carrier internetwork. Variable length packets are transmitted over Permanent Virtual Circuits (PVC) or Switched Virtual Circuits (SVC) Shared media across link X.25 Frame-Relay
Cell relay Similar to packet switching, but uses fixed length cells instead of variable length packets. Data is divided into fixed-length cells and then transported across virtual circuits best for simultaneous use of Voice and data Overhead can be considerable ATM

Transmission rate usually range from 1200 bits/second to 6 Mbit/s, although some connections such as ATM and Leased lines can reach speeds greater than 156 Mbit/s . Typical communication links used in WANs are telephone lines, microwave links & satellite channels. A leased line is a symmetric telecommunications line connecting two locations together. ... In computing, the Point-to-Point Protocol, or PPP, is commonly used to establish a direct connection between two nodes. ... It has been suggested that the section HDLC from the article Measuring_data_throughput be merged into this article or section. ... Synchronous Data Link Control (SDLC) is a computer communications protocol. ... In telecommunications, a circuit switching network is one that establishes a dedicated circuit (or channel) between nodes and terminals before the users may communicate. ... In telecommunication, the term dial-up has the following meanings: Dial-up access, typically to the Internet A service feature in which a user initiates service on a previously arranged trunk or transfers, without human intervention, from an active trunk to a standby trunk. ... In computing, the Point-to-Point Protocol, or PPP, is commonly used to establish a direct connection between two nodes. ... ISDN is also short for isosorbide dinitrate Integrated Services Digital Network (ISDN) is a type of circuit switched telephone network system, designed to allow digital (as opposed to analog) transmission of voice and data over ordinary telephone copper wires, resulting in better quality and higher speeds, than available with analog... In computer networking and telecommunications, packet switching is a communications paradigm in which packets (messages or fragments of messages) are individually routed between nodes, with no previously established communication path. ... A virtual circuit (VC) is a communications arrangement in which data from a source user may be passed to a destination user over more than one real circuit configuration during a single period of communication, but the switching is hidden from the users. ... A virtual circuit (VC) is a communications arrangement in which data from a source user may be passed to a destination user over more than one real circuit configuration during a single period of communication, but the switching is hidden from the users. ... X.25 is an ITU-T standard protocol suite for wide area networks using leased lines, the phone or ISDN system as the networking hardware. ... In the context of computer networking, frame relay consists of an efficient data transmission technique used to send digital information quickly and cheaply in a relay of frames to one or many destinations from one or many end-points. ... In telecommunications, cell relay refers to a method of statistically multiplexing fixed-length packets, i. ... In computer science, and moreso in computer programming, overhead is generally considered any combination of excess or indirect computation time, memory, bandwidth, or other resources that are required to be utilized or expended to enable a particular goal. ... Asynchronous Transfer Mode (ATM) is a cell relay, packet switching network and data link layer protocol which encodes data traffic into small (53 bytes; 48 bytes of data and 5 bytes of header information) fixed-sized cells. ...


Recently with the proliferation of low cost of Internet connectivity many companies and organizations have turned to VPN to interconnect their networks, creating a WAN in that way. Companies such as Cisco and Check Point offer solutions to create VPN networks. A Virtual Private Network, or VPN, is a private communications network usually used within a company, or by several different companies or organizations, communicating over a public network. ... Cisco may refer to: Cisco Systems, a computer networking company Cisco IOS, an internet router operating system CISCO Security Private Limited, a security company in Singapore Commercial and Industrial Security Corporation, a statutory board in Singapore Abbreviation for San Francisco, California Cisco (wine) The Cisco Kid, a fictional character created... Check Point Software Technologies Ltd. ...


References

  1. ^ a b Groth, David; Toby Skandier (2005). 'Network+ Study Guide, Fourth Edition'. Sybex, Inc.. ISBN 0-7821-4406-3. 
  2. ^ McQuerry, Steve (November 19, 2003). 'CCNA Self-Study: Interconnecting Cisco Network Devices (ICND), Second Edition'. Cisco Press. ISBN 1-58705-142-7. 

. is the 323rd day of the year (324th in leap years) in the Gregorian calendar. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ...


See Also

Computer networks may be classified according to the network layer at which they operate according to some basic reference models that are considered to be standards in the industry such as the seven layer OSI reference model and the four layer Internet Protocol Suite model. ... A personal area network (PAN) is a computer network used for communication among computer devices (including telephones and personal digital assistants) close to one person. ... “LAN” redirects here. ... In computing, a storage area network (SAN) is an architecture to attach remote computer storage devices such as disk array controllers, tape libraries and CD arrays to servers in such a way that to the operating system the devices appear as locally attached devices. ... In the case of a university campus-based campus area network the network is likely to link a variety of campus buildings including academic departments, the university library and student residence halls. ... Metropolitan area networks, or MANs, are large computer networks usually spanning a city. ... A leased line is a symmetric telecommunications line connecting two locations together. ... In telecommunications, a circuit switching network is one that establishes a dedicated circuit (or channel) between nodes and terminals before the users may communicate. ... In computer networking and telecommunications, packet switching is a communications paradigm in which packets (messages or fragments of messages) are individually routed between nodes, with no previously established communication path. ... In telecommunication, a cell relay is a statistically multiplexed interface protocol for packet switched data communications that uses fixed_length packets, i. ... Label switching is a form of network relaying to overcome the problems perceived by traditional IP-table switching. ... X.25 is an ITU-T standard protocol suite for wide area networks using leased lines, the phone or ISDN system as the networking hardware. ... In the context of computer networking, frame relay consists of an efficient data transmission technique used to send digital information quickly and cheaply in a relay of frames to one or many destinations from one or many end-points. ... ATM or atm may refer to: Look up ATM, atm in Wiktionary, the free dictionary. ... Synchronous optical networking, is a method for communicating digital information using lasers or light-emitting diodes (LEDs) over optical fiber. ... MPLS is a common abbreviation for Multiprotocol Label Switching. ... WWAN, which stands for Wireless Wide Area Network, is a form of wireless network. ... Wide Area File Services (WAFS) products allow remote office users to access and share files globally at LAN speeds over the WAN. Distributed enterprises that deploy WAFS solutions are able to consolidate storage to corporate datacenters, eliminating the need to backup and manage data that previously resided in their remote... Cisco Wide Area Application Services (WAAS) is technology developed by Cisco Systems that optimizes the performance of any TCP-based application operating in a wide area network (WAN) environment while preserving and strengthening branch security. ...

External Links

  • Cisco - Introduction to WAN Technologies
  • TechFest - Wide Area Network (WAN)

  Results from FactBites:
 
Wide area network - Wikipedia, the free encyclopedia (280 words)
A wide area network or WAN is a computer network covering a wide geographical area, involving a vast array of computers.
WANs are used to connect local area networks (LANs) together, so that users and computers in one location can communicate with users and computers in other locations.
X.25 was an important early WAN protocol, and is often considered to be the "grandfather" of Frame Relay as many of the underlying protocols and functions of X.25 are still in use today (with upgrades) by Frame Relay.
  More results at FactBites »

 
 

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