Indian railways also has its own wan which links its

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Unformatted text preview: xperience fewer data transmission errors than WANs do. Typically, bit error rates are in the range of 10-5 to 10-7 with WANs. 4. Communication link. The most common communication links used in LANs are twisted pair, coaxial cable, and fiber optics. On the other hand, since the sites in a WAN are physically distributed over a large geographic area, the communication links used are by default relatively slow and unreliable. Typical communication links used in WANs are telephone lines, and microwave links satellite channels. 5. Ownership. A LAN is typically owned by a single organization because of its limited geographic coverage. A WAN, however, is usually formed by interconnecting multiple LANs each of which may belong to a different organization. Therefore, administrative and maintenance complexities and costs for LANs are usually much lower than for WANs. 6. Communication cost. The overall communication cost of a LAN is usually much lower than that of a WAN. The main reasons for this are lower error rates, simple (or absence of) routing algorithms, and lower administrative and maintenance costs. Moreover, the cost to transmit data in a LAN is negligible since the transmission medium is usually owned by the user organization. However, with a WAN, this cost may be very high because the transmission media used are leased lines or public communication systems, such as telephone lines, microwave links, and satellite channels. Networks that share some of the characteristics of both LANs and WANs are sometimes referred to as metropolitan area networks (MANs). The MANs usually cover a wider geographic area (up to about 50 km in diameter) than LANs and frequently operate at speeds very close to LAN speeds. The main objective of MANs is to interconnect LANs located in an entire city or metropolitan area. Communication links commonly used for MANs are coaxial cable and microwave links. Ethernet is the most widely used LAN technology because it is relatively fast and economical. It was introduced by DEC (Digital Equip...
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This document was uploaded on 04/07/2014.

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