Data Communication Netwroks

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mmTASK 1
a) Explain the following types of data communication networks and their applications * Public switched telephone network (PSTN)
* Local area networks (LANs)
* Metropolitan area networks (MANs)
* Wide area networks (WANs)
* Packet switched data network (PSDN),
* Integrated services digital network (ISDN)

Public switched telephone network (PSTN)
Public Switched telephone network (PSTN) is the global collection of interconnects originally designed to support circuit-switched voice communication. The PSTN provides traditional Plain Old Telephone Service (POTS), also known as "landline phone" service, to residences and many other establishmenADD MORE INFORMATION OF PSTN DIAGRAM?

ts. Parts of the PSTN are also utilized for DSL, VoIP and other Internet-based network technologies. One PSTN link supports 64 kilobits per second (Kbps) of bandwidth for data. In residences, the PSTN phone line typically carries this bandwidth over a copper cable. Traditional dial-up network modems utilize nearly 56 Kbps of this bandwidth when connected to a phone line. Local area networks (LANs)

A local area network (LAN) supplies networking capability to a group of computers in close proximity to each other such as in an office building, a school, or a home. A LAN is useful for sharing resources like files, printers, games or other applications. A LAN in turn often connects to other LANs, and to the Internet or other WAN. Most local area networks are built with relatively inexpensive hardware such as Ethernet cables, network adapters, and hubs. Wireless LAN and other more advanced LAN hardware options also exist.

Metropolitan area networks (MANs)
A Metropolitan Area Network (MAN) is one of a number of types of networks (see also LAN and WAN). A MAN is a relatively new class of network, it serves a role similar to an ISP, but for corporate users with large LANs. There are three important features which discriminate MANs from LANs or WANs: * The network size falls intermediate between LANs and WANs. A MAN typically covers an area of between 5 and 50 km diameter. Many MANs cover an area the size of a city, although in some cases MANs may be as small as a group of buildings or as large as the North of Scotland. * A MAN (like a WAN) is not generally owned by a single organization. The MAN, its communications links and equipment are generally owned by either a consortium of users or by a single network provider who sells the service to the users. This level of service provided to each user must therefore be negotiated with the MAN operator, and some performance guarantees are normally specified. * A MAN often acts as a high speed network to allow sharing of regional resources (similar to a large LAN). It is also frequently used to provide a shared connection to other networks using a link to a WAN. A typical use of MANs to provide shared access to a wide area network is shown in the figure below:

Wide area networks (WANs)
Wide area networks(WAN) is a collection of computers and network resources connected via a network over a geographic area. Wide-Area Networks are commonly connected either through the Internet or special arrangements made with phone companies or other service providers. A WAN is different from a MAN because of the distance between each of the networks. In a WAN, one network may be anywhere from several hundred miles away, to across the globe in a different country. The term Wide Area Network (WAN) usually refers to a network which covers a large geographical area, and use communications circuits to connect the intermediate nodes. A major factor impacting WAN design and performance is a requirement that they lease communications circuits from telephone companies or other communications carriers. Transmission rates are typically 2 Mbps, 34 Mbps, 45 Mbps, 155 Mbps, 625 Mbps (or sometimes considerably more). Numerous WANs have been constructed, including public...
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