Wide area network
Encyclopedia
A wide area network is a telecommunication network that covers a broad area (i.e., any network that links across metropolitan, regional, or national boundaries). Business and government entities utilize WANs to relay data among employees, clients, buyers, and suppliers from various geographical locations. In essence this mode of telecommunication allows a business to effectively carry out its daily function regardless of location.
This is in contrast with personal area network
s (PANs), local area network
s (LANs), campus area network
s (CANs), or metropolitan area network
s (MANs) which are usually limited to a room, building, campus or specific metropolitan area (e.g., a city) respectively.
WANs necessarily do not just connect physically disparate LANs. A CAN, for example, may have a localised backbone of a WAN technology, which connects different LANs within a campus. This could be to facilitate higher bandwidth applications, or provide better functionality for users in the CAN.
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 provider
s, provide connections from an organization's LAN to the Internet. WANs are often built using leased line
s. At each end of the leased line, a router connects the LAN on one side with a second router within the LAN 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 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.
Academic research into wide area networks can be broken down into three areas: mathematical model
s, network emulation
and network simulation
.
Performance improvements are sometimes delivered via wide area file services
or WAN optimization
.
Transmission rates usually range from 1200 bit/s to 24 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.
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
, New Edge Networks and Check Point
offer solutions to create VPN networks.
This is in contrast with personal area network
Personal area network
A personal area network is a computer network used for communication among computer devices, including telephones and personal digital assistants, in proximity to an individual's body. The devices may or may not belong to the person in question. The reach of a PAN is typically a few meters...
s (PANs), local area network
Local area network
A local area network is a computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building...
s (LANs), campus area network
Campus area network
A campus network, campus area network, corporate area network or CAN is a computer network made up of an interconnection of local area networks within a limited geographical area...
s (CANs), or metropolitan area network
Metropolitan area network
A metropolitan area network is a computer network that usually spans a city or a large campus. A MAN usually interconnects a number of local area networks using a high-capacity backbone technology, such as fiber-optical links, and provides up-link services to wide area networks and the...
s (MANs) which are usually limited to a room, building, campus or specific metropolitan area (e.g., a city) respectively.
Design options
The textbook definition of a WAN is a computer network spanning regions, countries, or even the world. However, in terms of the application of computer networking protocols and concepts, it may be best to view WANs as computer networking technologies used to transmit data over long distances, and between different LANs, WANs and other localised computer networking architectures. This distinction stems from the fact that common LAN technologies operating at Layer 1/2 (such as the forms of Ethernet or Wifi) are often geared towards physically localised networks, and thus cannot transmit data over tens, hundreds or even thousands of miles or kilometres.WANs necessarily do not just connect physically disparate LANs. A CAN, for example, may have a localised backbone of a WAN technology, which connects different LANs within a campus. This could be to facilitate higher bandwidth applications, or provide better functionality for users in the CAN.
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 provider
Internet service provider
An Internet service provider is a company that provides access to the Internet. Access ISPs directly connect customers to the Internet using copper wires, wireless or fiber-optic connections. Hosting ISPs lease server space for smaller businesses and host other people servers...
s, provide connections from an organization's LAN to the Internet. WANs are often built using leased line
Leased line
A leased line is a service contract between a provider and a customer, whereby the provider agrees to deliver a symmetric telecommunications line connecting two or more locations in exchange for a monthly rent . It is sometimes known as a 'Private Circuit' or 'Data Line' in the UK or as CDN in Italy...
s. At each end of the leased line, a router connects the LAN on one side with a second router within the LAN on the other. Leased lines can be very expensive. Instead of using leased lines, WANs can also be built using less costly circuit switching
Circuit switching
Circuit switching is a methodology of implementing a telecommunications network in which two network nodes establish a dedicated communications channel through the network before the nodes may communicate. The circuit guarantees the full bandwidth of the channel and remains connected for the...
or packet switching
Packet switching
Packet switching is a digital networking communications method that groups all transmitted data – regardless of content, type, or structure – into suitably sized blocks, called packets. Packet switching features delivery of variable-bit-rate data streams over a shared network...
methods. Network protocols
Communications protocol
A communications protocol is a system of digital message formats and rules for exchanging those messages in or between computing systems and in telecommunications...
including TCP/IP deliver transport and addressing functions. Protocols including Packet over SONET/SDH
Packet over SONET/SDH
Packet over SONET/SDH, abbreviated POS, is a communications protocol for transmitting packets in the form of the Point to Point Protocol over SDH or SONET, which are both standard protocols for communicating digital information using lasers or light emitting diodes over optical fibre at high...
, MPLS
Multiprotocol Label Switching
Multiprotocol Label Switching is a mechanism in high-performance telecommunications networks that directs data from one network node to the next based on short path labels rather than long network addresses, avoiding complex lookups in a routing table. The labels identify virtual links between...
, ATM
Asynchronous Transfer Mode
Asynchronous Transfer Mode is a standard switching technique designed to unify telecommunication and computer networks. It uses asynchronous time-division multiplexing, and it encodes data into small, fixed-sized cells. This differs from approaches such as the Internet Protocol or Ethernet that...
and Frame relay
Frame relay
Frame Relay is a standardized wide area network technology that specifies the physical and logical link layers of digital telecommunications channels using a packet switching methodology...
are often used by service providers to deliver the links that are used in WANs. X.25
X.25
X.25 is an ITU-T standard protocol suite for packet switched wide area network communication. An X.25 WAN consists of packet-switching exchange nodes as the networking hardware, and leased lines, Plain old telephone service connections or ISDN connections as physical links...
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
X.25
X.25 is an ITU-T standard protocol suite for packet switched wide area network communication. An X.25 WAN consists of packet-switching exchange nodes as the networking hardware, and leased lines, Plain old telephone service connections or ISDN connections as physical links...
are still in use today (with upgrades) by Frame Relay.
Academic research into wide area networks can be broken down into three areas: mathematical model
Mathematical model
A mathematical model is a description of a system using mathematical concepts and language. The process of developing a mathematical model is termed mathematical modeling. Mathematical models are used not only in the natural sciences and engineering disciplines A mathematical model is a...
s, network emulation
Network emulation
Network emulation is a technique where the properties of an existing, planned and/or non-ideal network are simulated in order to assess performance, predict the impact of change, or otherwise optimize technology decision-making.-Methods of emulation:...
and network simulation
Network simulation
In communication and computer network research, network simulation is a technique where a program models the behavior of a network either by calculating the interaction between the different network entities using mathematical formulas, or actually capturing and playing back observations from a...
.
Performance improvements are sometimes delivered via wide area file services
Wide area file services
Wide area file services 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 back up and manage data that previously...
or WAN optimization
WAN Optimization
WAN optimization is a collection of techniques for increasing data-transfer efficiencies across wide-area networks. In 2008, the WAN optimization market was estimated to be $1 billion , and it will grow to $4.4 billion according to Gartner, a technology research firm.The most common measures of...
.
Connection technology options
Several options are available for WAN connectivity:| Option: | Description | Advantages | Disadvantages | Bandwidth range | Sample protocols used |
|---|---|---|---|---|---|
| Leased line Leased line A leased line is a service contract between a provider and a customer, whereby the provider agrees to deliver a symmetric telecommunications line connecting two or more locations in exchange for a monthly rent . It is sometimes known as a 'Private Circuit' or 'Data Line' in the UK or as CDN in Italy... |
Point-to-Point connection between two computers or Local Area Networks (LANs) | Most secure | Expensive | PPP Point-to-Point Protocol In networking, the Point-to-Point Protocol is a data link protocol commonly used in establishing a direct connection between two networking nodes... , HDLC, SDLC Synchronous Data Link Control Synchronous Data Link Control is a computer communications protocol. It is the layer 2 protocol for IBM's Systems Network Architecture . SDLC supports multipoint links as well as error correction. It also runs under the assumption that an SNA header is present after the SDLC header... , HNAS |
|
| Circuit switching Circuit switching Circuit switching is a methodology of implementing a telecommunications network in which two network nodes establish a dedicated communications channel through the network before the nodes may communicate. The circuit guarantees the full bandwidth of the channel and remains connected for the... |
A dedicated circuit path is created between end points. Best example is dialup connections | Less Expensive | Call Setup | 28 - 144 kbit/s | PPP Point-to-Point Protocol In networking, the Point-to-Point Protocol is a data link protocol commonly used in establishing a direct connection between two networking nodes... , ISDN |
| Packet switching Packet switching Packet switching is a digital networking communications method that groups all transmitted data – regardless of content, type, or structure – into suitably sized blocks, called packets. Packet switching features delivery of variable-bit-rate data streams over a shared network... |
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 X.25 X.25 is an ITU-T standard protocol suite for packet switched wide area network communication. An X.25 WAN consists of packet-switching exchange nodes as the networking hardware, and leased lines, Plain old telephone service connections or ISDN connections as physical links... Frame-Relay |
||
| Cell relay Cell relay In computer networking, cell relay refers to a method of statistically multiplexing small fixed-length packets, called "cells", to transport data between computers or kinds of network equipment. It is an unreliable, connection-oriented packet switched data communications protocol.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 Overhead Overhead may be:* Overhead , the ongoing operating costs of running a business* Engineering overhead, ancillary design features required by a component of a device... can be considerable |
ATM Asynchronous Transfer Mode Asynchronous Transfer Mode is a standard switching technique designed to unify telecommunication and computer networks. It uses asynchronous time-division multiplexing, and it encodes data into small, fixed-sized cells. This differs from approaches such as the Internet Protocol or Ethernet that... |
|
Transmission rates usually range from 1200 bit/s to 24 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.
Recently with the proliferation of low cost of Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
connectivity many companies and organizations have turned to VPN to interconnect their networks, creating a WAN in that way. Companies such as Cisco
Cisco
Cisco may refer to:Companies:*Cisco Systems, a computer networking company* Certis CISCO, corporatised entity of the former Commercial and Industrial Security Corporation in Singapore...
, New Edge Networks and Check Point
Check Point
Check Point Software Technologies Ltd. is a global provider of IT security solutions. Best known for its firewall and VPN products, Check Point first pioneered the industry with FireWall-1 and its patented stateful inspection technology...
offer solutions to create VPN networks.
See also
- Computer networkComputer networkA computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....
- Storage area network (SAN)Storage area networkA storage area network is a dedicated network that provides access to consolidated, block level data storage. SANs are primarily used to make storage devices, such as disk arrays, tape libraries, and optical jukeboxes, accessible to servers so that the devices appear like locally attached devices...
- InternetInternetThe Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
- Leased lineLeased lineA leased line is a service contract between a provider and a customer, whereby the provider agrees to deliver a symmetric telecommunications line connecting two or more locations in exchange for a monthly rent . It is sometimes known as a 'Private Circuit' or 'Data Line' in the UK or as CDN in Italy...
- Circuit SwitchingCircuit switchingCircuit switching is a methodology of implementing a telecommunications network in which two network nodes establish a dedicated communications channel through the network before the nodes may communicate. The circuit guarantees the full bandwidth of the channel and remains connected for the...
- Packet SwitchingPacket switchingPacket switching is a digital networking communications method that groups all transmitted data – regardless of content, type, or structure – into suitably sized blocks, called packets. Packet switching features delivery of variable-bit-rate data streams over a shared network...
- Cell Switching
- Label SwitchingLabel switchingLabel switching is a technique of network relaying to overcome the problems perceived by traditional IP-table switching...
- X.25X.25X.25 is an ITU-T standard protocol suite for packet switched wide area network communication. An X.25 WAN consists of packet-switching exchange nodes as the networking hardware, and leased lines, Plain old telephone service connections or ISDN connections as physical links...
- Frame RelayFrame relayFrame Relay is a standardized wide area network technology that specifies the physical and logical link layers of digital telecommunications channels using a packet switching methodology...
- ATMAsynchronous Transfer ModeAsynchronous Transfer Mode is a standard switching technique designed to unify telecommunication and computer networks. It uses asynchronous time-division multiplexing, and it encodes data into small, fixed-sized cells. This differs from approaches such as the Internet Protocol or Ethernet that...
- SONET/SDH
- Wireless Wide Area Network (WWAN)
- Wide Area File Services (WAFS)Wide area file servicesWide area file services 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 back up and manage data that previously...
- Wide Area Application Services (WAAS)Wide area application servicesCisco Wide Area Application Services is technology developed by Cisco Systems that optimizes the performance of any TCP-based application operating in a wide area network environment while preserving and strengthening branch security...