Telecommunications and Networks Chapter 6 Chapter 6

Telecommunications and Networks Chapter 6

Chapter 6, Telecommunications and Networks, describes basic concepts and components of networks used for data communications. After studying chapter 6, you should be able to address the learning objectives described in the following 2 slides. Chapter 6 Principles of Information Systems, Fifth Edition Slide 2

Learning Objectives Define “communications” and “telecommunications”. Describe the components of a telecommunications system. Identify & briefly discuss several telecommunications applications. Identify the benefits of a network. Chapter 6 Principles of Information Systems, Fifth Edition Slide 3

Networks have become the connective tissue of organizations. The effective use of telecommunications is critical for success in today’s world. In an environment where people must take action to seize opportunities or avert problems before their competitors do, having the right information at the right time is critical. Efficient and effective communication is a key to successful business. Chapter 6 Principles of Information Systems, Fifth Edition Slide 4

Learning Objectives Identify 3 basic types of communications media and the characteristics of each. Identify telecommunications hardware and the role each plays. Name 3 distributed processing alternatives & their features. Define “network topology” & identify five alternatives. Chapter 6 Principles of Information Systems, Fifth Edition Slide 5

In telecommunications, the trend is for greater volumes of more types of information to be transmitted more quickly. Understanding the technology that enables this is important. Chapter 6 Principles of Information Systems, Fifth Edition Slide 6

Overview of Telecommunications Systems

Communications is defined as the transmission of a signal over a medium from a sender to a receiver. Chapter 6 Principles of Information Systems, Fifth Edition Slide 8

Fig 6. 1 Principles of Information Systems, Fifth Edition

Fig 6. 2 Principles of Information Systems, Fifth Edition

In a conversation, a sender transmits a signal through the medium of the air. In a two-way conversation, the same person can be both a sender and a receiver. The signal is in words. For effective communication to occur, the sender must encode the signal in a way the receiver can understand. Therefore, in a conversation, both sender and receiver must speak the same language. Chapter 6 Principles of Information Systems, Fifth Edition Slide 11

Communication Flow Synchronous communication Asynchronous communication Chapter 6 Principles of Information Systems, Fifth Edition Slide 12

Telephone conversations are examples of synchronous communication. In synchronous communication, the receiver gets the message immediately. With asynchronous communication, the receiver gets the message at a late time – possibly even days after the message is sent. Sending a letter is an example of asynchronous communication, as is e-mail. Both synchronous and asynchronous communication are important in business. Chapter 6 Principles of Information Systems, Fifth Edition Slide 13

Fig 6. 3 Principles of Information Systems, Fifth Edition

Telecommunications is the electronic communication of signals, such as telephone, radio and television. Data communications is a subset of telecommunications referring to the electronic collection, processing, & distribution of data. Chapter 6 Principles of Information Systems, Fifth Edition Slide 15

Figure 6. 3 shows a model of telecommunications, with a computer as the sender. The computer sends the signal to a telecommunications device which facilitates electronic communication. This device then transmits the signal across a medium to another telecommunications device at the receiving end. This device receives the signal and sends it to the receiving computer. The process can then be reversed. This chapter covers the parts of this telecommunications model in greater detail. Chapter 6 Principles of Information Systems, Fifth Edition Slide 16

Data Transmission Speeds Measured in bits per second (bps) Kilobits per second (kbps) Megabits per second (Mbps) Gigabits per second (Gbps) Chapter 6 Principles of Information Systems, Fifth Edition Slide 17

Data communications is characterized by the speed at which the data is sent, measured in bits per second. The most common data transmission speeds range from thousands to millions of bits per second, or kilobits to megabits per second. Some networks can support transmission of billions of bits, or gigabits, per second. Chapter 6 Principles of Information Systems, Fifth Edition Slide 18

Computer Networks Telecommunications media Telecommunications devices Software Hardware devices Chapter 6 Principles of Information Systems, Fifth Edition Slide 19

A computer network consists of at least two computers or other devices connected by media, telecommunications devices and software that enable users to share data, information, and resources locally and worldwide. This chapter covers each of these components in more detail. Chapter 6 Principles of Information Systems, Fifth Edition Slide 20

Telecommunications Media

Types of Media Twisted Pair Coaxial Cable Fiber-Optic Cable Microwave Transmission Chapter 6 Principles of Information Systems, Fifth Edition Slide 22

The first 3 types of media – twisted pair, coaxial cable, and fiber optic cable – are usually referred to as guided or conducted media. That is, a signal is conducted over a physical medium. Microwave and other forms of wireless transmission are called broadcast media. Generally speaking, there are fewer errors in guided than in broadcast media. Chapter 6 Principles of Information Systems, Fifth Edition Slide 23

Different kinds of communications media have different characteristics, including different speeds and capacities. As with other components of an information system, the choice of medium depends on the purpose of the telecommunications system within the information system. The media selected should be the most adaptive, cost effective media that support these objectives. Media is critical in determining the overall system’s efficiency and effectiveness. Chapter 6 Principles of Information Systems, Fifth Edition Slide 24

Twisted Pair Fig 6. 4 Principles of Information Systems, Fifth Edition

Twisted pair cabling is made of pairs of copper wires twisted together. Twisted pair is used for the phone connection to your house. In networking it is common to see cable consisting of 4 pairs of wires. Each pair is twisted together to reduce electrical interference between neighboring pairs, or crosstalk. The more twists there are per foot, the less interference there will be. Twisted pair is classified by the number of twists per foot. Data grade cable has more twists per foot than does voice grade cable. Chapter 6 Principles of Information Systems, Fifth Edition Slide 26

Shielded twisted pair cabling includes additional shielding against external electro-magnetic interference. Unshielded twisted pair, although it doesn’t have the extra shielding, is used more often because of its lower costs and greater practicality. Chapter 6 Principles of Information Systems, Fifth Edition Slide 27

Coaxial Cable Fig 6. 5 Principles of Information Systems, Fifth Edition

Like twisted pair, coaxial cable, or “co-ax”, is also made from copper. However, because of extra shielding and insulation, coax has less interference, and therefore a higher capacity, or bandwidth, than does twisted pair. Data can be sent over coax at about 500 Mbps, whereas data transmission speeds over twisted pair for long distances are typically well below that, although in a local area network fast speeds can be attained using twisted pair. Chapter 6 Principles of Information Systems, Fifth Edition Slide 29

A type of coaxial cable is used for cable TV to your home. Cable modems can be used for Internet access several hundreds as times as fast as a modem and dialup phone line. Chapter 6 Principles of Information Systems, Fifth Edition Slide 30

Fiber Optic Cable Fig 6. 6 Principles of Information Systems, Fifth Edition

Unlike twisted pair and coax, fiber optic cable is made of thin filaments of glass or plastic, not of copper wire. Whereas a data signal travels over twisted pair or cable as electricity, signals are transmitted as light pulses over fiber. Lasers or LCDs produce the light. A thin coating, called cladding, prevents the light from leaving the strand. Also unlike copper media, fiber is not vulnerable to electro-magnetic interference. Chapter 6 Principles of Information Systems, Fifth Edition Slide 32

Fiber has a much higher bandwidth than does copper media – that is, it can carry more data faster. Fiber can have a capacity of billions of bits per second. Fiber is also the most secure medium around today. The biggest drawback of fiber is that labor costs to install and repair fiber are very high. Chapter 6 Principles of Information Systems, Fifth Edition Slide 33

Microwave Transmission Fig 6. 7 Principles of Information Systems, Fifth Edition

The expense of physical media can be great. Whereas broadcast media, such as microwave, don’t require the purchase of physical media, the hardware required is more expensive. Microwave is a high frequency radio signal. In terrestrial microwave, a signal travels directly between microwave transmission towers. This requires an unobstructed straight path between towers. Also, due to the curvature of the earth, towers must be spaced about 30 miles apart. Chapter 6 Principles of Information Systems, Fifth Edition Slide 35

Satellite Fig 6. 8 Principles of Information Systems, Fifth Edition

Satellite transmission involves sending a signal from a microwave tower to the satellite, which is basically a microwave station, then back to another microwave tower. Although this eliminates the need for a line-ofsight between towers, the delays to upload and download the signal often make satellite transmission impractical for sending signals short distance. Chapter 6 Principles of Information Systems, Fifth Edition Slide 37

Cellular Fig 6. 9 Principles of Information Systems, Fifth Edition

In cellular transmission, a service area is divided into cells. Cellular signals are integrated into the regular telephone network. Chapter 6 Principles of Information Systems, Fifth Edition Slide 39

Infrared Transmission Line of sight Short distances Chapter 6 Principles of Information Systems, Fifth Edition Slide 40

Infrared transmission can be used to send data short distances, for example, from a handheld computer to a desktop or a printer. Infrared transmission can also be used to connect peripherals, such as a mouse, to a computer. Chapter 6 Principles of Information Systems, Fifth Edition Slide 41

Telecommunications Devices

Telecommunications devices are hardware that make an electronic transmission occur or make it more efficient. Modems, multiplexers, and front-end processors are examples of telecommunications devices. Chapter 6 Principles of Information Systems, Fifth Edition Slide 43

Modems Analog signals: continuous Digital signals: discrete Modulation: translating digital data to analog Demodulation: translating analog data to digital Modems modulate & demodulate data Chapter 6 Principles of Information Systems, Fifth Edition Slide 44

Often, data is sent over the regular telephone network, which transmits analog signals. An analog signal is a continuous signal; the transmission line varies smoothly among an infinite number of states. Analog waves can carry a continuous range of data. On the other hand, computers produce digital signals. Digital signals send discrete pulses and represent a limited number of states. In the case of a computer, two states are represented. Chapter 6 Principles of Information Systems, Fifth Edition Slide 45

In order to send a digital signal over an analog line, the signal must first be modulated, or changed to a form that can be carried over an analog line. When the signal is received, it must be demodulated so the computer can understand it. This is what a modem does. Chapter 6 Principles of Information Systems, Fifth Edition Slide 46

Fig 6. 10 Principles of Information Systems, Fifth Edition

Modems are found between the sending computer and the phone line and between the receiving computer and the phone line. Modem transmission speeds are measured in bits per second. Typical modems today can download data at 56, 600 bits per second. Before a modem starts to send a message, it determines the receiving modem’s characteristics and adjusts its own speed to match. For example, if the other modem can only receive at 14. 4 kilobits per second, a faster modem will send at the slower speed. Chapter 6 Principles of Information Systems, Fifth Edition Slide 48

Fig 6. 11 Principles of Information Systems, Fifth Edition

Multiplexers are devices that combine signals from several computers to allow them to be sent over a single transmission line. Chapter 6 Principles of Information Systems, Fifth Edition Slide 50

Fig 6. 12 Principles of Information Systems, Fifth Edition

Front end processors are computers that manage communications to and from a computer system. This relieves the main computer of work so that it can be free to process other tasks. Front end processors are usually mainframes or midrange computers. Chapter 6 Principles of Information Systems, Fifth Edition Slide 52

Carriers and Services

Telecommunications carriers provide the technological infrastructure, such as lines and satellites, that enable data to be sent from one place to another. Carriers may also provide services to customers. Chapter 6 Principles of Information Systems, Fifth Edition Slide 54

Carriers Common carriers l Long distance carriers Value-added carriers Special purpose carriers l Additional services l Chapter 6 Principles of Information Systems, Fifth Edition Slide 55

Common carriers are the long distance telephone companies. Special purpose carriers offer services beyond long distance. Typically these are value-added carriers which are companies that sell services over their telecommunications systems to subscribers. Many common carriers are also value added carriers to some clients. Some value added carriers are third parties. Chapter 6 Principles of Information Systems, Fifth Edition Slide 56

Services Line types Switched l Dedicated l Private Branch Exchange (PBX) Wide-area telecommunications service (WATS) Phone & dialing services Chapter 6 Principles of Information Systems, Fifth Edition Slide 57

Switched lines are available from common carriers. Switches connect the sender’s and receiver’s phones. The call is sent along a specific, unchanging path, and only that call uses that path. When the parties hang up, all or part of the path is used by other calls. Dedicated, or leased, lines continuously connect two devices at fixed points. No dialing is required; the connection is always there. Although dedicated lines are expensive, if there is a lot of use, they are cheaper than dialup lines. Chapter 6 Principles of Information Systems, Fifth Edition Slide 58

A PBX system can manage voice and data within a building. Not only does the PBX internally route calls, but it can be used to connect a few external phone lines to numerous internal lines. WATS refers to the use of toll-free numbers. The company pays a fee to the phone company, depending on the volume of incoming or outgoing calls. WATS is very cost-effective for organizations that frequently make long distance calls. Chapter 6 Principles of Information Systems, Fifth Edition Slide 59

Common carriers provide increasingly more services to residential and commercial customers. For example, automatic number identification, more commonly called caller ID, can be used to display the caller’s phone number. In businesses, this can be integrated with databases to retrieve and display the customer’s record. Intelligent dialing is a service that will call back someone when their line is free after you get a busy signal. Chapter 6 Principles of Information Systems, Fifth Edition Slide 60

Services Digital subscriber lines (DSL) Integrated Services Digital Network (ISDN) T 1 Carrier Chapter 6 Principles of Information Systems, Fifth Edition Slide 61

DSL uses existing phone wires for fast connections for home and business. This means that users can download from the Internet at speeds over 500 kbps; upstream transmission (from the home or business out) may be slower. DSL is not universally available, although usage is growing fast. ISDN also uses existing common carrier lines to digitally send data, video, image or voice at speeds over 64 kilobits per second. A T 1 line is a digital carrier for data and image. T 1 lines are dedicated and costly. Chapter 6 Principles of Information Systems, Fifth Edition Slide 62

Table 6. 1 Principles of Information Systems, Fifth Edition

When choosing telecommunications services, individuals and businesses must consider the cost, speed, reliability and characteristics of each type. Table 6. 1 summarizes this information. T 1 lines are expensive dedicated lines, but cost effective for continual heavy users. They are also very fast, high capacity lines. DSL is more affordable and it is fairly fast; however, its availability is limited. Chapter 6 Principles of Information Systems, Fifth Edition Slide 64

Networks & Distributed Processing

Telecommunications networks are becoming increasingly important since they allow work to be done wherever and whenever it is most advantageous. Data, software, hardware, and other resources are becoming ubiquitous – that is, easily accessible by anyone, anytime, any place. Chapter 6 Principles of Information Systems, Fifth Edition Slide 66

Basic Processing Strategies Centralized processing Decentralized processing Distributed processing Chapter 6 Principles of Information Systems, Fifth Edition Slide 67

There are 3 basic processing strategies when more than 2 computer systems are used. In centralized processing, all processing is done at one location. This is the easiest strategy for the IS department to control and is appropriate when an enterprise needs a high level of security. In decentralized computing, different locations have their own processing devices. Devices at different locations aren’t connected together. This strategy works well when there are independent operating units and no data interchange between units. Chapter 6 Principles of Information Systems, Fifth Edition Slide 68

In distributed processing, computers at different locations are connected by a communications network. Data and processing are located where it is most efficient and effective. For example, data and programs used most by the Miami office would be located in Miami, and those used most by the Boston office would be in Boston. Users at both locations could access data and programs at the other site when needed. Chapter 6 Principles of Information Systems, Fifth Edition Slide 69

Network Concepts & Considerations Network topology Network types Local Area Networks l Wide Area Networks l International networks l Home & small business networks l Chapter 6 Principles of Information Systems, Fifth Edition Slide 70

Network topology describes how a network is logically organized – that is, how the data flows in the network. Depending on the distance between nodes and the services provided, networks may be classified as local area networks or wide area networks. Chapter 6 Principles of Information Systems, Fifth Edition Slide 71

Fig 6. 15 Principles of Information Systems, Fifth Edition

There are 5 main ways to arrange nodes in a network. In a ring network, devices are connected in a ring and message are routed around the ring from one device to the next. A bus network contains devices connected directly in a straight line. Each device can communicate directly with every other device one the network. In bus and ring topologies, there is no central coordinating computer. A hierarchical network is structured as an upside down tree like an organizational chart. Messages are passed to computers along the “branches”. Chapter 6 Principles of Information Systems, Fifth Edition Slide 73

As in the bus and ring networks, there is no coordinating computer. A star network has a central, coordinating device; each computer on the network is directly attached only to the central device. The central device is the vulnerability of the network – it can become a bottleneck under heavy traffic and the whole network fails if it fails. Many organizations use a combination of these various topologies, or a hybrid network. Chapter 6 Principles of Information Systems, Fifth Edition Slide 74

Network Types Logical Area Network (LAN) l Limited geographical area l Any topology possible l Network Interface Card (NIC) l Designs Peer-to-peer l Client-server l Wide Area Network (WAN) Chapter 6 Principles of Information Systems, Fifth Edition Slide 75

Local Area Networks connect processing devices within a limited geographic area and do not usually use common carrier facilities. Devices are attached to the media using network interface cards, also called network adapters. LANs can be designed in any of the topologies previously discussed and communications can be designed so that the network is peer-to-peer or clientserver. In a peer-to-peer network there are no computers dedicated as servers. All computers can be both servers of resources and clients requesting resources. Chapter 6 Principles of Information Systems, Fifth Edition Slide 76

This design is appropriate for small networks that don’t change much. In a client-server network, some computers are dedicated servers and provide applications, files, databases, telecommunications or other services to computers requesting those services, called clients. Client server networks are more appropriate for large, busy or dynamic networks, but do require professional network administration. Chapter 6 Principles of Information Systems, Fifth Edition Slide 77

Wide Area Networks connect devices over large geographic distances using common carrier facilities. Companies may use wide area networks provided by others, such as AT&T long distance service or may deploy their own WAN using enterprise facilities along with common carrier facilities. Chapter 6 Principles of Information Systems, Fifth Edition Slide 78

Network Types International networks Global l Transborder data flows l Infrastructure differences l Chapter 6 Principles of Information Systems, Fifth Edition Slide 79

Some enterprises’ wide area networks are international networks – that is, they connect facilities in different countries. Global networks present some challenges. They must comply with laws regulating the electronic transmission of data across borders. Some countries restrict the nature of information that can be sent electronically. Some countries have no laws about electronic data transmission and serve as data havens – that is, business may perform certain types of processing in those countries to avoid the laws of the countries in which they regularly do business. Chapter 6 Principles of Information Systems, Fifth Edition Slide 80

Another challenge is the inadequate telecommunications infrastructure in some countries that can cause problems or limit a network’s usefulness. Chapter 6 Principles of Information Systems, Fifth Edition Slide 81

Fig 6. 18 Principles of Information Systems, Fifth Edition

More and more individuals are deploying small networks for small businesses or home use. There are some products that try to make that easier by allowing a network to run over existing phone wiring or over existing electrical wiring. In the near future, we should see an increase in wireless LANs for home and small business use. Chapter 6 Principles of Information Systems, Fifth Edition Slide 83

Connecting Computers in a Distributed System Terminal-to-Host File Server Client/Server Chapter 6 Principles of Information Systems, Fifth Edition Slide 84

Terminal to host, file server, & client server systems are the most common ways to configure distributed computing. Chapter 6 Principles of Information Systems, Fifth Edition Slide 85

Fig 6. 19 Principles of Information Systems, Fifth Edition

In a terminal-to-host configuration, users have dumb terminals connected to a host computer. All file access and processing is done on the host. Chapter 6 Principles of Information Systems, Fifth Edition Slide 87

Fig 6. 20 Principles of Information Systems, Fifth Edition

In a file server environment, the file or database resides on a host computer, the file server, and applications, including the database management system, run on the user’s computer. All processing is done on the user’s computer. When an application needs a record, the file server sends the whole file. Chapter 6 Principles of Information Systems, Fifth Edition Slide 89

Fig 6. 21 Principles of Information Systems, Fifth Edition

In a client/server environment, some computers are designated as servers for specific tasks, such as printing, database management, printing, program execution, or communications. Network computers request services from the servers. Processing occurs on both the clients and the servers, so clients receive exactly the data or services needed. Potentially, a client/server environment can result in lower costs and improved performance, although a client/server environment is complex and costly and hard to manage. Chapter 6 Principles of Information Systems, Fifth Edition Slide 91

Communications Software and Protocols

Communications software is necessary for a network to function. Protocols are the rules and standards that allow devices to communicate with one another. Examples of a non-technology protocols are bowing before royalty or shaking hands when introduced at a business meeting. Some protocols are implemented in communications software. Chapter 6 Principles of Information Systems, Fifth Edition Slide 93

Communications Software Error checking Message formatting Security Network Operating System (NOS) Network Management Software Chapter 6 Principles of Information Systems, Fifth Edition Slide 94

Communications software, a necessary part of a network, performs such functions as error checking, message formatting, and communications log maintenance. Network Operating Systems performs the same functions for a network that an operating system does for a computer. When equipment on the network, such as databases or printers, is required, the network operating system intercepts the request and sends it to the network device. When a message is received from the network, the network operating system receives it for the computer. Chapter 6 Principles of Information Systems, Fifth Edition Slide 95

Network management software includes programs that allow a network manager to monitor activity and status of network devices from a single computer. Network management software can check for viruses, manage software licenses, or monitor device usage and traffic. Network management software also allows the manager to install new software and upgrades remotely over the network. Network management software improves efficiency of the network management function. Chapter 6 Principles of Information Systems, Fifth Edition Slide 96

Communications Protocols Fig 6. 22 Principles of Information Systems, Fifth Edition

Protocols are rules or standards that all devices on a network must follow in order to communicate successfully. Protocols are analogous to hardware standards discussed in Chapter 3: they allow interoperability of technology from different manufacturers. There are several different protocol frameworks or models. The Open Systems Interconnection (OSI) model is a standard framework for designing network architectures. The OSI model divides the data communications process into 7 layers. Chapter 6 Principles of Information Systems, Fifth Edition Slide 98

Different protocols handle functions at different layers. Layers allow protocols from different levels to be mixed and matched. The top layer of the OSI model, the Application Layer, defines standards for how the application running on a computer interacts with other applications on the network. The third OSI layer, the Network layer, defines how messages are routed through interconnected networks, such as the Internet. The bottom layer, the physical layer, defines electrical and interface standards that transmit bits over the media. Communicating devices must use the same standards at corresponding levels. Chapter 6 Principles of Information Systems, Fifth Edition Slide 99

The Internet protocol stack, also known as TCP/IP, is another protocol framework. It is commonly used and often replaces the top 5 layers of the OSI model in practice. You may be familiar with HTTP, an application layer protocol belonging to the Internet protocol stack. HTTP is a standard way for web browser software to communicate with web server software. Chapter 6 Principles of Information Systems, Fifth Edition Slide 100

Network Interconnectivity Technology

Most networks have interconnectivity devices – that is, hardware and software that connects them to other networks that use different standards or protocols. Bridges, routers, gateways, and switches are examples of these interconnectivity devices. Chapter 6 Principles of Information Systems, Fifth Edition Slide 102

Fig 6. 23 Principles of Information Systems, Fifth Edition

In its simplest form, a bridge connects two local area networks that use the same protocol at the second layer of the OSI model, the Data Link layer. A bridge forwards all messages that don’t have an address it recognizes as being from its “own” network, to the other network it is attached to. Routers are more complex than bridges, and connect networks that use different data link layer protocols. A router looks at the address on the message and determines which network to send it over. Many different networks can be connected to a router. Chapter 6 Principles of Information Systems, Fifth Edition Slide 104

Routers are the main device connecting the many networks making up the Internet. Gateways operate at OSI layers above the network layer and connect networks that are very dissimilar. Gateways connect networks that use different protocols in the top layers of the OSI stack. Gateways reformat messages so that they can be understood by dissimilar networks. Chapter 6 Principles of Information Systems, Fifth Edition Slide 105

Switches are now replacing bridges and gateways in many places. Switches can examine the address of a message and route it, but are more efficient and adaptable than older devices. Chapter 6 Principles of Information Systems, Fifth Edition Slide 106

Telecommunications Applications

Telecommunications networks are technological infrastructures that enterprises use to achieve business goals. Networks allow data to be accessed at remote locations, employees to communicate electronically with one another, as well as with clients and suppliers. In most companies, networks are necessary for doing business. Chapter 6 Principles of Information Systems, Fifth Edition Slide 108

Telecommunications Applications Voice & electronic mail Electronic software & document distribution Telecommuting Videoconferencing Chapter 6 Principles of Information Systems, Fifth Edition Slide 109

Many of you use voice and electronic mail daily – sometimes it hard to imagine life before e-mail. In electronic software distribution, software is installed on a file server for users to download to their desktop machines. This is much more efficient than having someone go to each computer to load the software. Some companies allow you to download software over the Internet. Telecommuting allows employees to work away from the office using personal computers and networks to stay in contact. Chapter 6 Principles of Information Systems, Fifth Edition Slide 110

Videoconferencing allows individuals to communicate verbally, as well as see one another and view the same documents. Chapter 6 Principles of Information Systems, Fifth Edition Slide 111

Fig 6. 24 Principles of Information Systems, Fifth Edition

Videoconferencing allows face to face meetings to be conducted among individuals in different locations without the time and expense of travel. Although much corporate videoconferencing involves large, specialized rooms and facilities, the technology exists to videoconference from desktop PCs. There also some trials today using videoconferencing between a patient at home and physician or nurse. Chapter 6 Principles of Information Systems, Fifth Edition Slide 113

Fig 6. 25 Principles of Information Systems, Fifth Edition

Electronic Data Interchange, EDI, is the computer-tocomputer exchange of data between companies or trading partners. Consider for example, part of the lifecycle of a purchase order for paint used in the manufacture of widgets at the ABC company. In a manual system, a buyer must create a purchase order (PO) and have it approved by a superior. If the PO wasn’t entered in on the computer, someone must enter it. When the PO arrives at the paint supplier, the order must be entered into the supplier’s computer system. When the order is shipped, an invoice is created, often with additional data entry. Chapter 6 Principles of Information Systems, Fifth Edition Slide 115

When ABC’s accounts payable clerk gets the invoice, he enters the information into the computer system, etc. Using EDI, the PO would be created on the computer and sent directly to the supplier’s computer, which would receive it and initiate the processing. All of the supplier’s computer systems would use the same database of information. The invoicing system, for example, would be notified (by the computer application) when the paint is shipped, and an invoice would automatically be electronically transmitted to ABC’s computer. Chapter 6 Principles of Information Systems, Fifth Edition Slide 116

ABC’s computer would schedule the invoice for payment (which would also be done electronically using electronic funds transfer between banks). The bottom line is that EDI reduces error and time involved in transactions by reducing, if not eliminating, human intervention. Chapter 6 Principles of Information Systems, Fifth Edition Slide 117

The ABC widget example used a direct EDI connection between the supplier and ABC. However, a third-party clearinghouse is sometimes used. In a direct connection, the supplier and customer must have compatible information systems and formatting. This can be costly or inconvenient. By using a thirdparty clearinghouse, data conversion and related services are done by the clearinghouse. Chapter 6 Principles of Information Systems, Fifth Edition Slide 118

Telecommunications Applications Distance learning Public Network Services Chapter 6 Principles of Information Systems, Fifth Edition Slide 119

You are familiar with distance learning as a telecommunications application. Distance learning is now being used for corporate training, as well as by traditional colleges & universities & commercial educational enterprises. It is expected that the use of distance learning will increase. Many of you might also be familiar with public network services. These are online content providers, such as AOL, and offer news, investment information, e-mail, virtual shopping malls, and many other services. Chapter 6 Principles of Information Systems, Fifth Edition Slide 120