CHAPTER 7 NOTES
Networking is an intriguing
concept, yet many of you do not realize that they take advantage of networking
daily. They may feel this subject is an unknown area. This chapter is best
handled with practical examples of networks the students use without their
knowledge, such as the telephone, ATM machines, and fax machines.
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1. A network
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a.
A network is computer equipment connected together to share resources.
Communications, the transmission of data across communications lines, is the key
to sharing. Basic components are a sending device, a communications link, and a
receiving device. The connection can be shared so that all processing is
performed at a central location, or to permit distributed processing by all
computers.
b. Activity: Make a list of various places where you believe a network is used. Which ones have you personally used without realizing they were commanding a network?
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2. Data transmission
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a. Analog
data transmission requires conversion between digital and analog signals. This
is accomplished by a modem. Our basic phone lines are analog. Digital
transmission requires digital phone lines. It is faster than analog. There are
many types of connections available. These include external and internal modems,
ISDN, DSL, cable modems, and cellular modems.
b. Activity: For each different connection types. research the availability, speed, and price to connect. Investigate the benefits and availability in your local area. Prepare a marketing flyer for your favorite connection.
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3. Types of transmission
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a.
Asynchronous and synchronous transmission help computers coordinate their
communications by providing signals to mark the start/stop of a message or by
coordinating the timing of the transmission. Once connected, transmission can be
simplex, half-duplex, or full-duplex.
b. Activity: Compare asynchronous transmission to taking turns to speak in the classroom. Each turn has a specific start (you are called upon) and end. Synchronous transmission might be a conversation in a crowded room. Conversation is coming in continuous streams. To insure you heard correctly, you might error-check: “If I understand you properly….” Have students identify simplex communication in school—a lecture class (teacher speaks, students listen); half-duplex transmission—teacher asks a question and student responds (communication both ways but one at a time); and full-duplex communication—a project has been assigned and students are whispering about their contribution and listening to instructions at the same time.
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4. Transmission medium
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a. Data can be transmitted via various media. These include twisted pairs, coaxial cables, fiber optics, microwave transmission, and satellite transmission. Bandwidth is a measure of the capacity of the link.
b. Activity: Compare bandwidth to a highway. The wider the highway, the more vehicles it can move at once.
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5. Protocols
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a.
A protocol is a set of rules governing communication. Networks must use
the same protocol to share data. Networks that use different protocols need a
translator. Bridges, routers, IP switches, and gateways connect networks. The
most common type of network protocol today is TCP/IP, which is used on the
Internet.
b. Activity: Determine if you know some people who speak a foreign language. Ask if they have relatives who do not speak English. What happens when their relatives need to communicate with a sales clerk for a purchase? The problems of multiple natural languages are the same as using different protocols.
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6. Topology
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a. Topology is the physical layout of the network. Review the three main configurations: bus, star, and ring.
b. Activity: Have some people arrange themselves in each configuration and pretend to pass data. Demonstrate what happens if one person fails to pass their data.
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7. WAN and LAN
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a. Wide area networks (WAN) connect computers over large distances. The connections can be via dedicated or dial-up lines. Local area networks (LAN) connect PCs to enable sharing. They are connected via cables or wireless transmission. The PCs need a NIC.
b. Activity: If you are in a networked lab, point out the NIC and the cable. If possible, trace the cables to see how they are connected. Note that most networks will have cables hidden in the walls. Ask the network administrator for a diagram of the network layout.
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8. Configuration
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a. Networks can be configured based on the interaction of computers with each other. Typical configurations include client/server and peer-to-peer. Networks generally use either Ethernet or token ring controls.
b. Activity: Divide your friends into two groups and assign 10 math problems. One group is to operate as a peer-to-peer network and take advantage of distributed processing. Every one does a portion of the problems. They need to determine how to combine the results into one list that is available to all. The second group is to use a client/server configuration. While all of your friends know the problems, only one can do the math and he/she will distribute the results to the others. Determine the benefits and shortcomings of each configuration.
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The Networked Home
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Networks aren’t just for businesses anymore. As more and more families become multiple-PC households, the need for home networking grows. Evaluate their home settings and see, in their opinion, which of the following three approaches to home networking would be suitable to them.
i. You can connect all your computers with cables and set up a miniature Ethernet or you can set up a wireless Wi-Fi network using low-power, high-frequency radio transceivers on each PC. However, if you find stringing a mess of cables all over the house unappealing and the wireless approach is too pricey, consider the following two alternatives that use existing home wiring.
ii. One approach uses the phone lines in your house to transmit data between computers without interfering with normal telephone use.
iii. If you don’t have telephone jacks near all your computers, you can use your home’s electrical wiring to connect your computers. Special adapters plug into the computer’s parallel or USB port, then into any wall outlet.
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Planet Internet - Online Privacy
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1. Read the section.
2. Do the exercises listed.