Wide area network

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A local area network (LAN) with connection to a wide area network (WAN) LAN WAN scheme.svg
A local area network (LAN) with connection to a wide area network (WAN)

A wide area network (WAN) is a telecommunications network that extends over a large geographic area. Wide area networks are often established with leased telecommunication circuits. [1]

Contents

Businesses, as well as schools and government entities, use wide area networks to relay data to staff, students, clients, buyers and suppliers from various locations around the world. In essence, this mode of telecommunication allows a business to effectively carry out its daily function regardless of location. The Internet may be considered a WAN. [2] Many WANs are, however, built for one particular organization and are private. WANs can be separated from local area networks (LANs) in that the latter refers to physically proximal networks.

Design options

The textbook definition of a WAN is a computer network spanning regions, countries, or even the world. [3] [4] However, in terms of the application of communication protocols and concepts, it may be best to view WANs as computer networking technologies used to transmit data over long distances, and between different networks. This distinction stems from the fact that common local area network (LAN) technologies operating at lower layers of the OSI model (such as the forms of Ethernet or Wi-Fi) are often designed for physically proximal networks, and thus cannot transmit data over tens, hundreds, or even thousands of miles or kilometres.

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 the LAN on one side with a second router within the LAN on the other. Because 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, Multiprotocol Label Switching (MPLS), Asynchronous Transfer Mode (ATM) and Frame Relay are often used by service providers to deliver the links that are used in WANs. It is also possible to build a WAN with Ethernet. [5]

Academic research into wide area networks can be broken down into three areas: mathematical models, network emulation, and network simulation.

Performance improvements are sometimes delivered via wide area file services or WAN optimization.

Private networks

Of the approximately four billion addresses defined in IPv4, about 18 million addresses in three ranges are reserved for use in private networks. Packets addressed in these ranges are not routable on the public Internet; they are ignored by all public routers. Therefore, private hosts cannot directly communicate with public networks, but require network address translation at a routing gateway for this purpose.

Reserved private IPv4 network ranges [6]
Name CIDR blockAddress rangeNumber of addressesObsolete classful description
24-bit block10.0.0.0/810.0.0.0 – 10.255.255.25516777216Single Class A.
20-bit block172.16.0.0/12172.16.0.0 – 172.31.255.2551048576Contiguous range of 16 Class B blocks.
16-bit block192.168.0.0/16192.168.0.0 – 192.168.255.25565536Contiguous range of 256 Class C blocks.

Since two private networks, e.g., two branch offices, cannot directly communicate via the public Internet, the two networks must be bridged across the Internet via a virtual private network (VPN) or other form of IP tunnel that encapsulates packets, including their headers containing the private addresses, for transmission across the public network. Additionally, encapsulated packets may be encrypted to secure their data.

Connection technology

Many technologies are available for wide area network links. Examples include circuit-switched telephone lines, radio wave transmission, and optical fiber. New developments have successively increased transmission rates. In c. 1960, a 110  bit/s line was normal on the edge of the WAN, while core links of 56 or 64 kbit/s were considered fast. Today, households are connected to the Internet with dial-up, asymmetric digital subscriber line (ADSL), cable, WiMAX, cellular network or fiber. The speeds that people can currently use range from 28.8 kbit/s through a 28K modem over a telephone connection to speeds as high as 100 Gbit/s using 100 Gigabit Ethernet.

The following communication and networking technologies have been used to implement WANs.

AT&T conducted trials in 2017 for business use of 400-gigabit Ethernet. [11] Researchers Robert Maher, Alex Alvarado, Domaniç Lavery, and Polina Bayvel of University College London were able to increase networking speeds to 1.125 terabits per second. [12] Christos Santis, graduate student Scott Steger, Amnon Yariv, Martin and Eileen Summerfield developed a new laser that potentially quadruples transfer speeds with fiber optics. [13]

See also

Related Research Articles

<span class="mw-page-title-main">Ethernet</span> Computer networking technology

Ethernet is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1983 as IEEE 802.3. Ethernet has since been refined to support higher bit rates, a greater number of nodes, and longer link distances, but retains much backward compatibility. Over time, Ethernet has largely replaced competing wired LAN technologies such as Token Ring, FDDI and ARCNET.

<span class="mw-page-title-main">Local area network</span> Computer network that connects devices over a limited area

A local area network (LAN) is a computer network that interconnects computers within a single physical location. It is the most common type of computer network, used in homes and buildings including offices or schools, for sharing data and devices between each other, including Internet access. Ethernet and Wi-Fi are the two most common technologies used for local area networks; historical network technologies include ARCNET, Token Ring and AppleTalk.

<span class="mw-page-title-main">Wake-on-LAN</span> Mechanism to wake up computers via a network

Wake-on-LAN is an Ethernet or Token Ring computer networking standard that allows a computer to be turned on or awakened from sleep mode by a network message. It is based upon AMD's Magic Packet Technology, which was co-developed by AMD and Hewlett-Packard, following its proposal as a standard in 1995. The standard saw quick adoption thereafter through IBM, Intel and others.

<span class="mw-page-title-main">Frame Relay</span> Wide area network technology

Frame Relay is a standardized wide area network (WAN) technology that specifies the physical and data link layers of digital telecommunications channels using a packet switching methodology. Originally designed for transport across Integrated Services Digital Network (ISDN) infrastructure, it may be used today in the context of many other network interfaces.

A network switch is networking hardware that connects devices on a computer network by using packet switching to receive and forward data to the destination device.

<span class="mw-page-title-main">Network topology</span> Arrangement of a communication network

Network topology is the arrangement of the elements of a communication network. Network topology can be used to define or describe the arrangement of various types of telecommunication networks, including command and control radio networks, industrial fieldbusses and computer networks.

<span class="mw-page-title-main">Metropolitan area network</span> Computer network serving a populated area

A metropolitan area network (MAN) is a computer network that interconnects users with computer resources in a geographic region of the size of a metropolitan area. The term MAN is applied to the interconnection of local area networks (LANs) in a city into a single larger network which may then also offer efficient connection to a wide area network. The term is also used to describe the interconnection of several LANs in a metropolitan area through the use of point-to-point connections between them.

<span class="mw-page-title-main">VLAN</span> Network communications domain that is isolated at the data link layer

A virtual local area network (VLAN) is any broadcast domain that is partitioned and isolated in a computer network at the data link layer. In this context, virtual refers to a physical object recreated and altered by additional logic, within the local area network. Basically, a VLAN behaves like a virtual switch or network link that can share the same physical structure with other VLANs while staying logically separate from them. VLANs work by applying tags to network frames and handling these tags in networking systems, in effect creating the appearance and functionality of network traffic that, while on a single physical network, behaves as if it were split between separate networks. In this way, VLANs can keep network applications separate despite being connected to the same physical network, and without requiring multiple sets of cabling and networking devices to be deployed.

The data link layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between nodes on a network segment across the physical layer. The data link layer provides the functional and procedural means to transfer data between network entities and may also provide the means to detect and possibly correct errors that can occur in the physical layer.

<span class="mw-page-title-main">Network interface controller</span> Hardware component that connects a computer to a network

A network interface controller is a computer hardware component that connects a computer to a computer network.

The Point-to-Point Protocol over Ethernet (PPPoE) is a network protocol for encapsulating Point-to-Point Protocol (PPP) frames inside Ethernet frames. It appeared in 1999, in the context of the boom of DSL as the solution for tunneling packets over the DSL connection to the ISP's IP network, and from there to the rest of the Internet. A 2005 networking book noted that "Most DSL providers use PPPoE, which provides authentication, encryption, and compression." Typical use of PPPoE involves leveraging the PPP facilities for authenticating the user with a username and password, via the PAP protocol or via CHAP. PAP was dominant in 2007 but service providers have been transitioning to the more secure CHAP, because PAP is a plain-text protocol. Around 2000, PPPoE was also starting to become a replacement method for talking to a modem connected to a computer or router over an Ethernet LAN displacing the older method, which had been USB. This use-case, connecting routers to modems over Ethernet is still extremely common today.

<span class="mw-page-title-main">Internet access</span> Individual connection to the Internet

Internet access is a facility or service that provides connectivity for a computer, a computer network, or other network device to the Internet, and for individuals or organizations to access or use applications such as email and the World Wide Web. Internet access is offered for sale by an international hierarchy of Internet service providers (ISPs) using various networking technologies. At the retail level, many organizations, including municipal entities, also provide cost-free access to the general public. Types of connections range from fixed-line cable to mobile and satellite.

A leased line is a private telecommunications circuit between two or more locations provided according to a commercial contract. It is sometimes also known as a private circuit, and as a data line in the UK. Typically, leased lines are used by businesses to connect geographically distant offices.

<span class="mw-page-title-main">Link aggregation</span> Using multiple network connections in parallel to increase capacity and reliability

In computer networking, link aggregation is the combining of multiple network connections in parallel by any of several methods. Link aggregation increases total throughput beyond what a single connection could sustain, and provides redundancy where all but one of the physical links may fail without losing connectivity. A link aggregation group (LAG) is the combined collection of physical ports.

<span class="mw-page-title-main">Metro Ethernet</span> Metropolitan area network based on Ethernet standards

A metropolitan-area Ethernet, Ethernet MAN, carrier Ethernet or metro Ethernet network is a metropolitan area network (MAN) that is based on Ethernet standards. It is commonly used to connect subscribers to a larger service network or for internet access. Businesses can also use metropolitan-area Ethernet to connect their own offices to each other.

In computer networking, an edge device is a device that provides an entry point into enterprise or service provider core networks. Examples include routers, routing switches, integrated access devices (IADs), multiplexers, and a variety of metropolitan area network (MAN) and wide area network (WAN) access devices. Edge devices also provide connections into carrier and service provider networks. An edge device that connects a local area network to a high speed switch or backbone may be called an edge concentrator.

<span class="mw-page-title-main">Computer network</span> Network that allows computers to share resources and communicate with each other

A computer network is a set of computers sharing resources located on or provided by network nodes. Computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are made up of telecommunication network technologies based on physically wired, optical, and wireless radio-frequency methods that may be arranged in a variety of network topologies.

In a hierarchical telecommunications network, the backhaul portion of the network comprises the intermediate links between the core network, or backbone network, and the small subnetworks at the edge of the network.

<span class="mw-page-title-main">Ethernet physical layer</span> Electrical or optical properties between network devices

The physical-layer specifications of the Ethernet family of computer network standards are published by the Institute of Electrical and Electronics Engineers (IEEE), which defines the electrical or optical properties and the transfer speed of the physical connection between a device and the network or between network devices. It is complemented by the MAC layer and the logical link layer. An implementation of a specific physical layer is commonly referred to as PHY.

<span class="mw-page-title-main">10 Gigabit Ethernet</span> Standards for Ethernet at ten times the speed of Gigabit Ethernet

10 Gigabit Ethernet is a group of computer networking technologies for transmitting Ethernet frames at a rate of 10 gigabits per second. It was first defined by the IEEE 802.3ae-2002 standard. Unlike previous Ethernet standards, 10GbE defines only full-duplex point-to-point links which are generally connected by network switches; shared-medium CSMA/CD operation has not been carried over from the previous generations of Ethernet standards so half-duplex operation and repeater hubs do not exist in 10GbE. The first standard for faster 100 Gigabit Ethernet links was approved in 2010.

References

  1. ↑ Mitchell, Bradley. "What Is a Wide Area Network (WAN)?". Lifewire. Archived from the original on 2018-06-12. Retrieved 2017-04-21.
  2. ↑ Groth, David; Skandler, Toby (2005). Network+ Study Guide, Fourth Edition. Sybex, Inc. ISBN   0-7821-4406-3.
  3. ↑ Forouzan, Behrouz (2012-02-17). Data Communications and Networking. McGraw-Hill. p. 14. ISBN   9780073376226.
  4. ↑ Zhang, Yan; Ansari, Nirwan; Wu, Mingquan; Yu, Heather (2011-10-13). "On Wide Area Network Optimization". IEEE Communications Surveys & Tutorials. 14 (4): 1090–1113. CiteSeerX   10.1.1.459.4653 . doi:10.1109/SURV.2011.092311.00071. ISSN   1553-877X. S2CID   18060. Archived from the original on 2022-02-08. Retrieved 2022-01-29.
  5. ↑ CCNA Data Center DCICN 640-911 Official Cert Guide. Cisco Press. 14 November 2014. ISBN   978-0-13-378782-5.
  6. ↑ Y. Rekhter; B. Moskowitz; D. Karrenberg; G. J. de Groot; E. Lear (February 1996). Address Allocation for Private Internets. Network Working Group IETF. doi: 10.17487/RFC1918 . BCP 5. RFC 1918.
  7. ↑ "Selecting a WAN Technology (1.2) > WAN Concepts | Cisco Press".
  8. ↑ "Selecting a WAN Technology (1.2) > WAN Concepts | Cisco Press".
  9. ↑ "Selecting a WAN Technology (1.2) > WAN Concepts | Cisco Press".
  10. ↑ "Selecting a WAN Technology (1.2) > WAN Concepts | Cisco Press".
  11. ↑ "AT&T Completes Industry-Leading 400 Gb Ethernet Testing, Establishing A Future Network Blueprint for Service Providers and Businesses". www.att.com. September 8, 2017. Archived from the original on January 5, 2022. Retrieved August 20, 2018.
  12. ↑ Maher, Robert; Alvarado, Alex; Lavery, Domaniç; Bayvel, Polina (11 February 2016). "Increasing the information rates of optical communications via coded modulation: a study of transceiver performance". Scientific Reports. 6 (1): 21278. Bibcode:2016NatSR...621278M. doi:10.1038/srep21278. PMC   4750034 . PMID   26864633.
  13. ↑ "A New Laser for a Faster Internet - Caltech". Cal Tech. 19 February 2014. Archived from the original on 2017-05-11. Retrieved 2017-02-05.
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