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This third edition of the best-selling Networking Complete is a one-of-a-kind computer book—valuable for its broad content and its low price. This book contains updated coverage of the essential information you need to know about networking, both in the office and in the home.
With Networking Complete, you'll learn about designing, installing, maintaining, and administering networks using a variety of operating systems, including Windows 2000, Mac OS, NetWare 6, Linux, and UNIX. You'll quickly take advantage of all that networking has to offer. Get up to speed with the basics, then move on to develop intranet systems. Finally, an extensive section on network security and firewalls will help you ensure the reliability and security of your home or business network.
The reference section contains a comprehensive networking glossary, which you'll find to be an invaluable daily tool. Finally, you can examine the exciting IT consulting career opportunities awaiting you.
Networking Complete introduces you to the work of some of Sybex's finest authors, so you'll know where to go to learn even more about what's possible with your network.
* An Introduction to Networking
* Networks in the Workplace
* Topologies and Network Types
* OSI Model and Major Protocol Suites
* Wireless—Cell, Radio, Satellite
Networking Hardware and Software
* Installing Cards and Cables
* Repeaters, Hubs, Routers, Switches, and Bridges
* Network Operating Systems and Client Software
* Networking with Windows 2000 and Windows XP
* Thin Client Networking Using Citrix MetaFrame XP
* Web Applications
Network Design, Maintenance, and Troubleshooting
* Principles of Network Design
* Home Networking Choices
* Managing Windows 2000 Networks
* Network Troubleshooting and Disaster Recovery
Intranets and Interconnecting Networks
* Building an Intranet Infrastructure
* Remote Access Concepts
* Java, E-Commerce, ASP
* Security Concepts and Terminology
* NetWare 6 Network Security
* Unix Security
* Virtual Private Networking
* L2TP, PPTP, RADIUS
* Firewalls, Proxy Servers, and Encryption
* How to Become an IT Consultant
Imagine 20 years ago working in an office with little or no computer equipment. It's hard to imagine now, isn't it? One could say that we take for granted a lot of what we have gained in technology the past few decades. Now, imagine having to send a memo to everyone in the company. Back then we used interoffice mail; today we use e-mail. This is one form of communication that only became available due to the introduction and growth of networks.
This chapter focuses on the basic concepts surrounding how a network works, including the way it sends information and what it uses to send information. This information is covered only to a minor degree by the A+ certification exam. However, if you have interest in becoming a service technician, this information will prove to be very useful, as you will in all likelihood find yourself asked to troubleshoot both hardware and software problems on existing networks. Included in this chapter is information on:
* What is a network?
* Network types
* Media types
* Connectivity devices
If you find that the material in this chapter interests you, you might consider studying for, and eventually taking, CompTIA's Network+ exam. It is a generic networking certification (similar to A+, only it is for network-related topics). You can study for it using Sybex's Network+ Study Guide materials available at sybex.com.
What Is aNetwork?
Stand-alone personal computers, first introduced in the late 1970s, gave users the ability to create documents, spreadsheets, and other types of data and save them for future use. For the small business user or home computer enthusiast, this was great. For larger companies, however, it was not enough. The larger the company, the greater the need to share information between offices, and sometimes over great distances. The stand-alone computer was not enough for the following reasons:
* Their small hard drive capacities were inefficient.
* To print, each computer required a printer attached locally.
* Sharing documents was cumbersome. People grew tired of having to save to a diskette, then taking that diskette to the recipient. (This procedure was called "sneakernet.")
* There was no e-mail. Instead, there was interoffice mail, which was not reliable and frequently was not delivered in a timely manner.
To address these problems, networks were born. A network links two or more computers together to communicate and share resources. Their success was a revelation to the computer industry as well as businesses. Now, departments could be linked internally to offer better performance and increase efficiency.
You have heard the term "networking" in the business context, where people come together to exchange names for future contact and to gain access to more resources. The same is true with a computer network. A computer network allows computers to link to each other's resources. For example, in a network every computer does not need a printer connected locally to print. Instead, one computer has a printer connected to it and allows the other computers to access this resource. Because they allow users to share resources, networks offer an increase in performance as well as a decrease in the outlay for new hardware and software.
LANs vs. WANs
Local area networks (LANs) were introduced to connect computers in a single office. Wide area networks (WANs) came to expand the LANs to include networks outside of the local environment and also to distribute resources across distances. Today, LANs can be seen in many businesses, from small to large. WANs are becoming more widely accepted as businesses are becoming more mobile and as more of them are spanning greater and greater distances. It is important to have an understanding of LANs and WANs as a service professional, because when you're repairing computers, you are likely to come in contact with problems that are associated with the computer being connected to a network.
Local Area Networks (LANs)
The 1970s brought us the minicomputer, which was a smaller version of the mainframe. Whereas the mainframe used centralized processing (all programs ran on the same computer), the minicomputer used distributed processing to access programs across other computers. As depicted in Figure 1.1, distributed processing allows a user at one computer to use a program on another computer as a "back end" to process and store the information. The user's computer is the "front end," performing the data entry. These allowed programs to be distributed across computers rather than centralized. This was also the first time computers used cable to connect rather than phone lines.
By the 1980s, offices were beginning to buy PCs in large numbers. Also, portables were introduced, allowing computing to become mobile. Neither PCs nor portables, however, were efficient in sharing information. As timeliness and security became more important, diskettes were just not cutting it. Offices needed to find a way to implement a better means to share and access resources. This led to the introduction of the first type of PC LAN: ShareNet by Novell. LANs are simply the linking of computers to share resources within a closed environment. The first simple LANs were constructed a lot like Figure 1.2.
After the introduction of ShareNet, more LANs sprouted. The earliest LANs could not cover a great distance. Most of them could only stretch across a single floor of the office and could support no more than 30 users. Further, they were still simple, and only a few software programs supported them. The first software programs that ran on a LAN were not capable of permitting more than one user at a time to use a program (this constraint was known as file locking). Nowadays, we can see multiple users accessing a program at one time, limited only by restrictions at the record level.
Wide Area Networks (WANs)
By the late 1980s, networks were expanding to cover ranges considered geographical in size and were supporting thousands of users. Wide area networks, first implemented with mainframes at massive government expense, started attracting PC users as networks went to this whole new level. Businesses with offices across the country communicated as if they were only desks apart. Soon the whole world would see a change in its way of doing business, across not only a few miles but across countries. Whereas LANs are limited to single buildings, WANs are able to span buildings, states, countries, and even continental boundaries. Figure 1.3 gives an example of a simple WAN.
Networks of today and tomorrow are not limited anymore by the inability of LANs to cover distance and handle mobility. WANs play an important role in the future development of corporate networks worldwide. Although the primary focus of this chapter is LANs, we will feature a section on WAN connectivity. This section will briefly explain the current technologies and what you should expect to see in the future. If you are interested in more information on LANs or WANs, or if you plan on becoming a networking technician, check your local library resources or the Internet.
Primary Network Components
Putting together a network is not as simple as it was with the first PC network. You can no longer consider two computers cabled together a fully functional network. Today, networks consist of three primary components:
* Clients or workstations
No network would be complete without these three components working together.
Servers come in many shapes and sizes. They are a core component of the network, providing a link to the resources necessary to perform any task. The link it provides could be to a resource existing on the server itself or a resource on a client computer. The server is the "leader of the pack," offering directions to the client computers regarding where to go to get what they need.
Servers offer networks the capability of centralizing the control of resources and can thus reduce administrative difficulties. They can be used to distribute processes for balancing the load on the computers and can thus increase speed and performance. They can also offer the departmentalizing of files for improved reliability. That way, if one server goes down, then not all of the files are lost.
Servers perform several tasks. For example, servers that provide files to the users on the network are called file servers. Likewise, servers that host printing services for users are called print servers. (There are other tasks as well, such as remote access services, administration, mail, etc.) Servers can be multi-purpose or single-purpose. If they are multi-purpose, they can be, for example, both a file server and a print server at the same time. If the server is a single-purpose server, it is a file server only or print server only.
Another distinction we use in categorizing servers is whether they are dedicated or nondedicated:
Dedicated Servers These are assigned to provide specific applications or services for the network, and nothing else. Because a dedicated server is specializing in only a few tasks, it requires fewer resources from the computer that is hosting it than a nondedicated server might require. This savings in overhead may translate to a certain efficiency and can thus be considered as having a beneficial impact on network performance.
Nondedicated Servers These are assigned to provide one or more network services and local access. A nondedicated server is expected to be slightly more flexible in its day-to-day use than a dedicated server. Nondedicated servers can be used not only to direct network traffic and perform administrative actions, but often to serve as a front end for the administrator to work with other applications or services. The nondedicated server is not really what some would consider a true server, because it can act as a workstation as well as a server.
Many networks use both dedicated and nondedicated servers in order to incorporate the best of both worlds, offering improved network performance with the dedicated servers and flexibility with the nondedicated servers.
Workstations or Client Computers
Workstations are the computers that the users on a network do their work on, performing activities such as word processing, database design, graphic design, e-mail, and other office or personal tasks. Workstations are basically nothing more than an everyday computer, except for the fact that they are connected to a network that offers additional resources. Workstations can range from a diskless computer system to a desktop system. In network terms, workstations are also known as client computers. As clients, they are allowed to communicate with the servers in the network in order to use the network's resources.
It takes several items to make a workstation into a client. You must install a network interface card (NIC), a special expansion card that allows the PC to talk on a network. You must connect it to a cabling system that connects to another computer (or several other computers). And you must install some special software, called client software, which allows the computer to talk to the servers. Once all this has been accomplished, the computer will be "on the network."
To the client, the server may be nothing more than just another drive letter. However, because it is in a network environment, the client is able to use the server as a doorway to more storage or more applications, or through which it may communicate with other computers or other networks. To a user, being on a network changes a few things:
* They can store more information, because they can now store data on other computers on the network.
* They can now share and receive information from other users, perhaps even collaborating on the same document.
* They can use programs that would be too large for their computer to use by itself.
We now have the server to share the resources and the workstation to use them, but what about the resources themselves? A resource (as far as the network is concerned) is any item that can be used on a network. Resources can include a broad range of items, but the most important ones include:
* Printers and other peripherals
* Disk storage
When an office can purchase paper, ribbons, toner, or other consumables for only one, two, or maybe three printers for the entire office, the costs are dramatically lower than the costs for supplying printers at every workstation. Networks also give more storage space to files. Client computers are not always able to handle the overhead involved in storing large files (for example, database files) because they are already heavily involved in the day-to-day work activities of the users. Because servers in a network can be dedicated to only certain functions, a server can be allocated to store all the larger files that are worked with every day, freeing up disk space on client computers. Similarly, applications (programs) no longer need to be on every computer in the office. If the server is capable of handling the overhead an application requires, the application can reside on the server and be used by workstations through a network connection.
The sharing of applications over a network requires a special arrangement with the application vendor, who may wish to set the price of the application according to the number of users who will be using it. The arrangement allowing multiple users to use a single installation of an application is called a site license.
Network Operating Systems (NOSs)
PCs use a disk operating system that controls the file system and how the applications communicate with the hard disk. Networks use a network operating system (NOS) to control the communication with resources and the flow of data across the network. The NOS runs on the server. Many companies offer software to start a network. Some of the more popular network operating systems at this time include Unix, Novell's NetWare, and Microsoft's Windows NT Server (or Windows 2000). Although several other NOSs exist, these three are the most popular.
Back in the early days of mainframes, it took a full staff of people working around the clock to keep the machines going. With today's NOSs, servers are able to monitor memory, CPU time, disk space, and peripherals, without a baby-sitter. Each of these operating systems allows processes to respond in a certain way with the processor.
With the new functionality of LANs and WANs, you can be sitting in your office in Milwaukee and carry on a real-time electronic "chat" with a coworker in France, or maybe print an invoice at the home office in California, or manage someone else's computer from your own while they are on vacation. Gone are the days of disk-passing, phone messages left but not received, or having to wait a month to receive a letter from someone in Hong Kong. NOSs provide this functionality on a network.
Network Resource Access
Now that we have discussed the makeup of a typical network, let's discuss the way resources are accessed on a network. There are generally two resource access models: peer-to-peer and server-based. It is important to choose the appropriate model. How do you decide what type of resource model is needed? You must first think about the following questions:
* What is the size of the organization?
* How much security does the company require?
* What software or hardware does the resource require?
* How much administration does it need?
* How much will it cost?
* Will this resource meet the needs of the organization today and in the future?
* Will additional training be needed?
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Part I: Networking Fundamentals.
Chapter 1: An Introduction to Networks.
Chapter 2: Networks in the Workplace.
Chapter 3: Network Topologies and Types.
Chapter 4: The OSI Model.
Chapter 5: Major Protocol Suites.
Part II: Network Hardware and Software.
Chapter 6: Installing Cards and Cables.
Chapter 7: Network Connectivity Devices.
Chapter 8: Network Operating Systems.
Chapter 9: Configuring Network Hardware.
Chapter 10: Controlling Network Applications.
Chapter 11: Thin Client Networking.
Chapter 12: Extending Terminal Services.
Part III: Network Design, Maintenance, andTroubleshooting.
Chapter 13: The Principles of Network Design.
Chapter 14: Home Networking Technologies.
Chapter 15: Network Troubleshooting.
Chapter 16: Diagnosing Real-World Problems.
Chapter 17: Disaster Recovery.
Part IV: Intranets and Interconnecting Networks.
Chapter 18: Managing Network Connections.
Chapter 19: Intranet and Internet Services.
Chapter 20: Website Connectivity.
Part V: Network Security.
Chapter 21: Security with Certificates.
Chapter 22: Firewalls and Your Network.
Chapter 23: Securing Your NetWare 6 Network.
Chapter 24: Remote Connectivity.
Appendix A: Beyond Network Administration.
Appendix B: Glossary of Networking Terms.
Appendix C: Information on the Internet.
Appendix D: Certification Programs.
Appendix E: ASCII Character Set.
Appendix F: EBCDIC Character Set.