A Wide Area Network (WAN) is a collection of computers and computer-related equipment interconnected to perform a given function or functions and typically using local and long-distance telecommunications systems. WANs operate beyond a local area network’s (LAN) geographic scope by using serial connections of various types of access bandwidth over wide area geographic demography. Some of the data transmission carriers that operate or offer services over WAN include Sprint, MCI, Verizon, etc. The types of computers used within a wide area network range from microcomputers to mainframes. The telecommunications lines can be as simple as a standard telephone line or as advanced as a satellite system. WANs are typically used to transfer bulk data between two end points and provide users with electronic mail services, access to database systems, and access to the Internet. WANS can also assist with specialized operations in many fields, such as manufacturing, medicine, navigation, education, entertainment, and telecommunications.

The wide area networks cross-continents and are the backbone of the Internet, which supports the World Wide Web (WWW). And the most common WAN devices that make it possible for it to extend over this wide geographical area include: routers, which offer support internetworking and WAN interface ports; WAN bandwidth switches, which connect to WAN bandwidth for voice, data, and video communication; communication servers, which facilitate dial-in and dial-out user communication; and modems, which interface voice-grade services. Connections between networks frequently use a telephone system service called T1, which provides a transfer rate of 1.544 megabits per second over a leased line. For sites requiring faster access (Internet access), T1s are collected into multiple-T1 units that work in parallel to provide more throughput. For instance, T3 is composed of 28T1 connections and has a transfer rate of 45 mbps. And the routers control the path each message takes through the network.

WAN standards are defined and managed by a number of recognized authorities, such as International Organization of Standardization (ISO), Internet Engineering Task Force (IETF), Electronic Industries Association (EIA), and so forth. WAN standards basically describe both physical-layer and data-link-layer. The WAN physical-layer etiquette describes how to provide electrical, mechanical, operational, and functional connections for WAN services obtained from WAN providers, such as telephone and telegraph agencies. In addition, there are several physical-layer interface standards that facilitate communication, such as EIA/TIA-449, a physical-layer interface developed by EIA and TIA, which is a faster version of EIA/TIA-232 and capable of longer cable runs. Another example is the X.21, an ITU-T standard primarily used in Japan and Europe for serial communications over synchronous digital lines.

While data-link-layer set of rules describe how frames are carried between systems on a single data link, designed to operate over dedicated point-to-point, multipoint, and multi-access switched services, such as Frame Relay, High-Level Data Link (HDLC), ISDN, and so forth. For example the Point-t-point protocol (PPP) provides router-to-router and host-to-network connections over synchronous and asynchronous circuits. Likewise, High-Level Data Link (HDLC) that was developed by ISO specifies data encapsulation method on synchronous serial links using frame characters and checksum.  HDLC supports both point-to-point and multipoint configurations.

WAN uses a mesh design (in which only the neighbors are connected to neighbors) and require routing (or telephone switching) to transfer data across the network. Thus, to transmit data across a mesh network, the data has to be passed along a route from workstation to workstation. That is, all WANs are collections of at least two basic types of equipment: a station and a node. A station is a device like workstation, terminal, or telephone that a user interacts with to access a network, and it contains the software application that allows someone to use the network for a particular purpose. While a node is a device like router that allows one or more stations to access the physical network and is a transfer point for passing information through the network. When data or information travels through a network, the information is transferred from node to node through the network. When the information arrives at the proper destination, the destination node delivers it to the destination station.

The support structure of a wide area network is the communications network, which is a collection of nodes and interconnecting telecommunications links. The communications network is the underlying physical interconnection of nodes/computers and communication lines that transfer the data from one location to another. There are three main WAN types of communications network that may be categorized according to the way they transfer information from one end of the communications network to another.  The types of communications networks include: circuit-switched networks, packet-switched networks, and broadcast networks. In Circuit-switched network communications, a dedicated circuit is established between the sender and receiver, and all data passes over a circuit. An example is a circuit established between a telephone caller and recipient of the call in a dial-up telephone system.

While, with packet-switched network communication, data being transmitted is broken down into fixed-sized packages called packets, and no dedicated physical path is established. An example is data transmitted over the Internet. There are at least two types of packet-switched network, namely: datagram packet-switched network and virtual circuit packet-switched network. The broadcast network, though rare now, is when a node on a WAN transmits data and all the nodes receive the data. This system uses radio frequency to broadcast to all node/workstations. Some of the wireless Internet access services such as Multi-channel Multipoint Distribution Services are based on a broadcast network.

Lastly, the logical infrastructure of WAN includes applications such as email, web browsing, and so forth. These applications fall under connection-oriented network application and connectionless-oriented network application. Connection-oriented network application is the more reliable of the two and one that performs file transfer using FTP with a guarantee that information traveling through the network will not get lost and all information will be received at the final destination. While connectionless-oriented network application like the email program does not guarantee the delivery of information to the intended destination since there is no connection negotiation.

The technologies in WAN have advanced over the years and the best is yet to come.


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