Data communications — the sending and receiving of facts, figures, details, and other information over a communications network — support us in our everyday activities both at home and at work. For businesses, data communications have become vital to success in the marketplace, particularly with the increasing trend toward globalization. Communications networks allow both individuals and teams to communicate faster and better, obviate the need for many in-person meetings, and even transfer funds electronically. Through local, metropolitan, or wide area networks, individual computers or workstations can be linked together to enable data sharing and communication. Networks can also be linked with each other to better meet the needs of the organization and the growing demands for communication and data in the Information Age.
Keywords Architecture; Bandwidth; Communications Channel; Communications Network; Data Communications; Server; Wireless Communications System; Workstation
Information Technology: Data Communications
Data communications have become so much a part of our lives that we often take them for granted, yet they provide an infrastructure for the way that we do so much in the 21st century. For example, to postpone the inevitable task of sitting down to write this article, I just ordered a book from a large, online-only bookstore. I was able to search the online database for books on the topic in which I was interested. When I had narrowed down the list to a few books that seemed to meet my requirements, I was not only able to read the book reviews that had been stored in another database, but was also able to read facsimiles of a chapter from each of the books online. Once I made my selection, I was able to place my order online, an activity made easier because the business had my shipping information saved in another database; all I had to do was confirm that the information was still correct. My payment was verified and approved via a secure transaction and funds were electronically transferred from my account to the business for the purchase. I was then sent an automatic e-mail confirming my order. The order request was also sent to the shipping department who will pick my order, pack it, generate a shipping receipt using my stored information to generate a shipping label, and enter the shipment into the system of the carrier. The carrier will then track the shipment — and allow me to do the same from the comfort of my own computer. Upon delivery, the driver for the shipping carrier will enter confirmation into the carrier's database that the package has been delivered. If I have problems with the delivery or the shipment itself, I will be able to contact customer service for the bookstore or the carrier, often communicating with people not only in other states but in other countries in order to get the proper book delivered to my desk. At no time, however, will I have actually talked to a live person. The entire transaction and the sub-steps that make it possible will all have been done through the technology of data communications networks.
Even if I had decided that I would prefer to physically go to a local bookstore and peruse the book over a cup of coffee, data communications networks would have made my task easier. I might have gone to an electronic kiosk in the store or to the information desk to find out what books they had on the topic and where they were located. In either case, I would have received the information from a remote database delivered over their network. When my order was placed with the barista in the coffee shop, it would have been entered into the computerized cash register which would not only have rung up my transaction, but would have most likely also entered it into another database that keeps track of inventory and would either remind the store manager to order more sugar-free hazelnut syrup or have automatically ordered it itself. Sales information on my cup of coffee would also have been transmitted to corporate headquarters at the end of the day. After picking up my purchase, I would have then sat down with my book and coffee, perhaps also tapping into the wireless Internet connection to read my e-mail or compare prices for the book with those of the online bookstore.
Data communications — the sending and receiving of facts, figures, details, and other information over a communications network — is a vital part of our lives today. Information transmission is no longer limited to what we can place on paper. Large computer systems can hold and manipulate quantities of data in ways that just a few decades ago would have seemed impossible. Not only can these be linked together in a myriad of ways, but can also be transmitted nearly instantaneously over communications networks — sets of locations (or nodes) with concomitant hardware, software, and information that are linked together to form a system that transmits and receives information.
There are three types of data communications networks. Local area networks comprise multiple desktop computers that are located near each other and linked into a network that allows the users to share files and peripheral devices such as printers, fax machines, or storage devices. Local area networks are used to connect computers in an office or series of offices, and span distances from a few hundred feet to a few miles. The computers linked into a local area network are also referred to as workstations, clients, or nodes. These are connected to a server — a host computer for the network that provides services to the clients. The server usually has more storage capacity and can process at higher speeds than the client computers.
A second type of network used in many businesses is the metropolitan area network. This type of network transmits data and information citywide (up to 30 miles) and at greater speeds than a local area network. As opposed to local area networks, metropolitan area networks are optimized for both voice and data transmissions and can, therefore, carry more forms of data than can be carried over local area networks. These include combinations of voice, data, image, and video data. Metropolitan area networks typically operate over a city-wide network of fiber optic cables. These networks enable metropolitan area networks to provide high quality multimedia transmissions at higher speeds than is possible over local area networks.
The third type of network is the wide area network. These networks comprise multiple computers that are widely dispersed and that are linked into a network. Wide area networks typically use high speed, long distance communications networks or satellites to connect the computers within the network. There are many uses for a wide area network. A retail chain, for example, may use a wide area network to connect its stores across the country or across the world, allowing them to share inventory and sales data and to send e-mail messages to each other. Similarly, computerized cash registers can be used to collect and transmit sales data at each location and transmit them to the company's corporate headquarters as part of the closing procedure each day.
Wide area networks link their network using services provided by a common carrier — a company that provides public communications transmission services. The speed at which the data are transmitted is determined by the bandwidth. This is the data transfer rate, or the amount of data that can be transmitted within a given time period. The higher the bandwidth of a transmission is, the higher the transfer rate is. Bandwidth is expressed in thousands of bits of information per second (kbps), millions of bits per second (mbps), or billions of bits per second (gbps). For example, a typical page of typed correspondence contains approximately 275 words, which translates to 2000 bytes or 16,000 bits of information. To transmit this amount of data over a 56 kbps modem takes approximately .28 second, whereas sending the same page over a high speed network transmitting at 1.544 mbps would only take .01 second. A small difference if one is only transmitting one page. However, transmission of a 600 page document at 2,400 Bps would take nearly two hours, at 56,000 Bps would take only 5 minutes, and at 1.544 mbps would take a mere 10.8 seconds. Although it is seldom...
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