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VERBAL QUESTION OF THE DAY |
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Two switching mechanisms are used for data transfer: circuit-switched and packet-switched. Circuit-switched networks establish a physical connection between the two communicating parties. This connection is maintained for the duration of the connection and cannot be used by ay other parties. Landline telephone networks are circuit-switched. When you make a telephone call, you are granted a connection to the person you are talking to. The line becomes available again only after the conversation is finished and one party hangs up. Thus, for every conversation, a dedicated line is required.
Circuit-switching works well for voice communication where there is a constant stream of data being transferred, but is very inefficient for many forms of data communication where information is requested in bursts, such as when browsing Web pages, because even when no data is being transferred, the connection has to be maintained. This adds additional cost to consumers, as they pay according to the time connected to the network, not by the amount of data downloaded. From the wireless operators' perspective it is also wasteful, as they cannot use that connection for any other purpose. Additionally, if the connection is lost, the user has to establish a new connection, a process that takes anywhere from 5 to 40 seconds.
Packet-switched networks solve these problems. They do not require dedicated connections, but rather allow several users to share a single connection to maximize spectrum. Internet traffic uses packet-based networks for data transmission. This works by dividing data into small units called packets. These packets are then assigned a destination address that they carry around as they are being routed through the network. Multiple users can share the same data path since the data packets do not have to follow any specific path to get to their destination. This allows them to take the optimal path for bandwidth efficiency. At the receiving end, the data packets are then reassembled into their original format.
[Mallick, Martyn. Mobile and Wireless Design Essentials. Indianapolis, IN. Wiley Technology Publishing. © 2003 p. 66]
2. Packet switched networks offer the ability to:
a. Share the resources of the network among any number of users.
b. Provide private connections to each desired end-point.
c. Monopolize the resources of the network for short periods of time.
d. Bill users on a per-connection basis.
e. Provide full-duplex connections in 5 to 40 seconds.
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 Answer |
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