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Chapter 1: Networking and The OSI Reference Model
In this chapter, you will learn about important networking terms and concepts. In addition, you will learn about two different types of networks: Local-area networks (LANs), which make it possible for businesses using computer technology to efficiently share such things as files and printers m Wide-area networks (WANs), which make it possible for businesses to communicate with each other even though they are geographically distant from each other Finally, you will learn about the Open System Interconnection (OSI) reference model and the communication process between the lower layers of the OSI reference model.
Networking is the interconnection of workstations, peripherals (such as printers, hard drives, scanners, and CD-ROMs), and other devices. In networking, it is possible for different types of computers to communicate. It is not important what type of computer is used on a network. It may be a Macintosh, a PC, or a mainframe. In networking, what is important is that all the devices speak the same language, or protocol, which is a formal description of a set of rules and conventions that govern how devices on a network exchange information. For example, if a group of people are assigned to work as a team to complete a project, it does not matter if those people are French, German, Italian, American, Chinese, or Mexican. What is important is that they be able to communicate through a common language. In today's world, the team most likely would speak English. In computing, a protocol would function like English in this example because, like English, the protocol is a common language that can be understood by all devices on a network.
Why and How Did Networking Start?
Early computers were standalone devices. In other words, each computer operated on its own, independently from other computers. It soon became apparent that this was not an efficient or cost-effective way for businesses to operate. A solution was needed that would successfully address three problems:
- Duplication of equipment and resources
- Inability to communicate efficiently
- Lack of network management
- Operate within a limited geographic area
- Allow many users to access high-bandwidth media
- Provide full-time connectivity to local services
Businesses needed a way to move information efficiently and quickly from one LAN to another. The solution was the creation of WANs. WAlVs interconnect LANs to provide access to computers or file servers in other locations. Because WANs connect networks that serve users across a large geographic area, they make it possible for businesses to communicate with each other even though they are geographically distant.
By networking or connecting computers, printers, and other devices on a WAN so they can communicate with each other, as shown in Figure 1-1, it is possible to share information and resources, as well as to access the Internet.
The Need for Standards
During the past two decades there has been a tremendous expansion of WANs. As organizations realized how much money they could save and how much productivity they could gain by using network technology, they began adding networks and expanding existing networks almost as rapidly as new network technologies and products were introduced. Consequently, many of the networks were built using different hardware and software implementations...