CCENT/CCNA ICND1 Official Exam Certification Guide - Chapter 1

Chương này cung cấp cho bạn một cái nhìn nhẹ nhàng về mạng, làm thế nào họ ban đầu được tạo ra, và lý do tại sao mạng lưới làm việc theo cách họ làm. Mặc dù không có thực tế cụ thể từ chương này xảy ra được trên bất kỳ của các kỳ thi CCNA, chương này sẽ giúp bạn chuẩn bị cho chiều sâu của chủ đề mà bạn sẽ bắt đầu đọc trong Chương 2, "The TCP / IP và mô hình Mạng OSI" Nếu bạn là thương hiệu mới để kết nối mạng, chương giới...
Nội dung trích xuất từ tài liệu:
CCENT/CCNA ICND1 Official Exam Certification Guide - Chapter 1 1828xbook.fm Page 3 Thursday, July 26, 2007 3:10 PM Part I: Networking Fundamentals Chapter 1 Introduction to Computer Networking Concepts Chapter 2 The TCP/IP and OSI Networking Models Chapter 3 Fundamentals of LANs Chapter 4 Fundamentals of WANs Chapter 5 Fundamentals of IP Addressing and Routing Chapter 6 Fundamentals of TCP/IP Transport, Applications, and Security 1828xbook.fm Page 4 Thursday, July 26, 2007 3:10 PM 1828xbook.fm Page 5 Thursday, July 26, 2007 3:10 PM 1 CHAPTER Introduction to Computer Networking Concepts This chapter gives you a light-hearted perspective about networks, how they were originally created, and why networks work the way they do. Although no specific fact from this chapter happens to be on any of the CCNA exams, this chapter helps you prepare for the depth of topics you will start to read about in Chapter 2, “The TCP/IP and OSI Networking Models.” If you are brand new to networking, this short introductory chapter will help you get ready for the details to follow. If you already understand some of the basics of TCP/IP, Ethernet, switches, routers, IP addressing, and the like, go ahead and skip on to Chapter 2. The rest of you will probably want to read through this short introductory chapter before diving into the details. Perspectives on Networking So, you are new to networking. You might have seen or heard about different topics relating to networking, but you are only just now getting serious about learning the details. Like many people, your perspective about networks might be that of a user of the network, as opposed to the network engineer who builds networks. For some, your view of networking might be based on how you use the Internet, from home, using a high-speed Internet connection. Others of you might use a computer at a job or at school, again connecting to the Internet; that computer is typically connected to a network via some cable. Figure 1-1 shows both perspectives of networking. End-User Perspective on Networks Figure 1-1 CATV Ethernet Home User Cable Cable PC with Ethernet Card The Internet Office User Ethernet Cable PC with Ethernet Card The top part of the figure shows a typical high-speed cable Internet user. The PC connects to a cable modem using an Ethernet cable. The cable modem then connects to a cable TV (CATV) outlet on the wall using a round coaxial cable—the same kind of cable used to connect your TV to the CATV wall outlet. Because cable Internet services provide service 1828xbook.fm Page 6 Thursday, July 26, 2007 3:10 PM 6 Chapter 1: Introduction to Computer Networking Concepts continuously, the user can just sit down at the PC and start sending e-mail, browsing websites, making Internet phone calls, and using other tools and applications as well. Similarly, an employee of a company or a student at a university views the world as a connection through a wall plug. Typically, this connection uses a type of local-area network (LAN) called Ethernet. Instead of needing a cable modem, the PC connects directly to an Ethernet-style socket in a wall plate (the socket is much like the typical socket used for telephone cabling today, but the connector is a little larger). As with high-speed cable Internet connections, the Ethernet connection does not require the PC user to do anything first to connect to the network—it is always there waiting to be used, similar to the power outlet. From the end-user perspective, whether at home, at work, or at school, what happens behind the wall plug is magic. Just as most people do not really understand how cars work, how TVs work, and so on, most people who use networks do not understand how they work. Nor do they want to! But if you have read this much into Chapter 1, you obviously have a little more interest in networking than a typical end user. By the end of this book, you will have a pretty thorough understanding of what is behind that wall plug in both cases shown in Figure 1-1. The CCNA exams, and particularly the ICND1 (640-822) exam, focus on two major ...