Chapter 1: Introduction to NetworkingLesson 1: What Is a NetworkLesson Checkup1. What is a computer network? A computer network is a system in which a number of independent computers are linked together to share data and peripherals, such as hard disks and printers. 2. What are three advantages of using a computer network? Three advantages of using a computer network are the ability to share information (or data), to share hardware and software, and to centralize administration and support. 3. Give two examples of a LAN configuration. The most basic version of a LAN is two computers that are connected by a cable. An example of a more complex LAN is hundreds of connected computers and peripherals scattered throughout a large organization, such as a municipality. In both cases, the LAN is confined to a limited geographic area. 4. Give two examples of a WAN configuration. Because a WAN has no geographical limitations, it can connect computers and other devices in separate cities or on opposite sides of the world. A multinational corporation with linked computers in different countries is using a WAN. Probably the ultimate WAN is the Internet.
Lesson 2: Network ConfigurationLesson Checkup1. List three factors that can influence the choice of whether to implement a peer-to-peer or server-based network configuration. Three factors that can influence the choice of whether to implement a peer-to-peer or server-based network configuration are the size of the organization, the level of security required, and the type of business being conducted. Other factors include the level of administrative support available, the amount of network traffic, the needs of the network users, and the network budget.
2. Describe the advantages of a peer-to-peer network. Peer-to-peer networks are relatively simple and inexpensive. They require no dedicated servers and no administrators, and are connected by a simple, easily visible cabling system. 3. Describe the advantages of a server-based network. Server-based networks have a number of advantages over peer-to-peer networks. They can accommodate a larger number of users; they have servers which can be specialized to accommodate the expanding needs of users; and they offer greater security. Server-based networks also support e-mail systems along with application and fax servers.
Exercise 1.1: Case Study Problem1. Which type of network would you suggest for this company? o Peer-to-peer o Server-based There is no completely right or wrong answer to this problem, but a server-based network is suggested. Although there are only seven people in the entire company at present, and thus a peer-to-peer network seems adequate, the company is experiencing growth. Additionally, some of the information that will be sent over the network is confidential. It is better to invest in a server-based network that can accommodate growth and provide centralized security than to choose a peer-to-peer network that growth will render obsolete in a year or two. 2. Which network topology would be most appropriate in this situation? o Bus o Ring o Star o Mesh o Star bus o Star ring There is no single correct answer. The most commonly installed networks currently are the star bus and the bus. A hub-centered star bus seems to be the best choice because of the ease of troubleshooting and reconfiguration. Although a bus network might be chosen for its low cost or ease of installation, it does not offer the centralized troubleshooting or administrative advantages of a hub. A ring is probably more complex than is necessary for this network.
Exercise 1.2: Troubleshooting Problem1. Why are problems arising concerning who has which document? Suggest at least one reason. The network has clearly outgrown the friendly, trusting, give-and-take style of the workgroup. The number of new users, the undefined nature of their responsibilities on the network, and the increased traffic of network-intensive applications make the peer-to-peer approach inadequate. 2. What one change could you make that would give you centralized control of the access to these documents? Add a dedicated server and administrator, and implement a network operating system that can provide extensive, centralized security. 3. Describe one change that your solution will bring to the users' operating environment. Changing from peer-to-peer to server-based networking will disrupt the organization's routine, present everyone with the challenge of adjusting to a new communications milieu, and change the entire personality of the work environment. However, the change is required in order for the organization to network successfully. This is why planning is so important in implementing a network. Network planners need to stay current with evolving networking technologies, anticipate future changes in the number of devices, and make purchasing decisions that are cost-effective.
Exercise 1.3: Network Planning Problem/Part 1The following answer pertains to Questions 1 through 8: An appropriate choice between peer-to-peer and server-based networking can be made only after careful consideration of:o o o o
The projected number of users The users' need for access to data Network management The number of computers acting as servers
A server-based network imposes a greater cost than a peer-to-peer network because at least one of the computers on the network is dedicated to serving data, applications, or both. But a server-based network also makes the best use of a centralized, coherent administration of resources. This centralized administration can regulate access to data, making it secure.
Exercise 1.3: Network Planning Problem/Part 2The following answer pertains to Questions 1 through 5: If some of your servers are going to support more than one of these applications and the number of users is large (25 users or more), you should consider adding more servers and dedicating them to specialized tasks. Some of these tasks, such as database, e-mail, or application serving, can be resource-intensive. Each of these often requires its own server in order to provide acceptable performance. Other server tasks, such as user directories and general data storage, are not usually so demanding of resources and may be combined on a single computer. And some tasks, such as backup, are usually scheduled in such a way that their impact on network performance occurs during periods of low network activity.
Exercise 1.3: Network Planning Problem/Part 3The following answer pertains to questions 1 through 10: Choosing an appropriate topology for your network is often difficult. The most common network being installed today is the star bus, but that might not meet your needs. There are several criteria you can usebased on the information you generated in Part 3 of the Network Planning Problemto help you make this decision. Again, there is no one completely correct choice.o o
If you need an extremely reliable network with redundancy built in, you might want to consider either a ring or a star-wired ring network. There are at least three considerations involved in estimating the cost of implementing a certain topology: Installation Troubleshooting Maintenance Eventually, topology translates into cabling, and the installation phase is where theoretical topology meets the real world of the actual network. If cost is an overriding factor, then perhaps you should choose the topology that you can install at the lowest cost. Ninety percent of the cost of wiring is applied to labor. Anytime cabling has to be permanently installed in any kind of structure, the initial cost multiplies rapidly because of the high cost of labor and expertise. When a network requires installing cable in a structure, a star bus is usually less expensive to install than a bus. To illustrate this, imagine the task of wiring a large building for a bus network. Then, imagine what it would take to reconfigure that network six months later to add eight new computers. Finally, imagine how much more economically and efficiently those same operations could be performed if the installation were a star bus.
For a small network (5-10 users), a bus is usually economical to install initially but may be expensive to maintain because troubleshooting and reconfiguring take time. However, on a larger network (20 or more users), installing a star bus may cost more initially than installing a bus, owing to the cost of the equipment (a hub); but a star bus will be significantly less expensive to maintain in the long run. Finally, if there is installed network cabling that you can reuse, you might choose the existing topology if it meets your needs.
Exercise SummaryBased on the information generated in the three parts of this Network Planning Problem, your network components should be: Type of network: server-based Type of topology: Star
Chapter Review1. Describe the difference between a LAN and a WAN. A LAN, or local area network, is the basic building block of any computer network. It can consist of a simple network (two computers connected by a cable and sharing information) or up to several hundred computers connected and sharing information and resources. A LAN has geographical limits, but a WAN has no geographical limits. A WAN can connect several departments within the same building or buildings on opposite sides of the world. Today, the ultimate WAN is the World Wide Web. 2. What are the two basic network configurations? The two basic network configurations are peer-to-peer and server-based. 3. A primary reason for implementing a network is to _______ resources. share 4. Name three key resources often shared on a network. There are many resources to be shared on a network; among them are printers, scanners, applications, files, and network access to the World Wide Web.
5. In a