1. ©Brooks/Cole, 2003 Chapter 6 Computer Networks

2. ©Brooks/Cole, 2003 Understand the rationale for the existence of networks. Distinguish between the three types of networks: LANs, MANs, and WANs. After reading this chapter, the reader should be able to: O BJECTIVES List different connecting devices and the OSI layers in which each device operates. Understand client-server models. Understand the OSI model and TCP/IP.

3. ©Brooks/Cole, 2003 NETWORKS, LARGE AND SMALL (LAN, MAN, WAN) NETWORKS, LARGE AND SMALL (LAN, MAN, WAN) 6.1

4. ©Brooks/Cole, 2003 OSI MODEL 6.2

5. ©Brooks/Cole, 2003 The Open Systems Interconnection model is a theoretical model that shows how any two different systems can communicate with each other. Note:

6. ©Brooks/Cole, 2003 Figure 6-1 The OSI model

7. ©Brooks/Cole, 2003 Figure 6-2 Flow of data in the OSI model Bit stream  signal Frames (node  node) Packet (logical address) Entire message Synchronization points Coding methods User  network

8. ©Brooks/Cole, 2003 CATEGORIESOFNETWORKSCATEGORIESOFNETWORKS 6.3

9. Figure 6-3 Categories of networks

10. ©Brooks/Cole, 2003 Figure 6-4 LANs

11. ©Brooks/Cole, 2003 Figure 6-5 MAN

12. ©Brooks/Cole, 2003 Figure 6-6 WAN

13. ©Brooks/Cole, 2003 CONNECTINGDEVICESCONNECTINGDEVICES 6.4

14. Figure 6-7 Connecting devices

15. ©Brooks/Cole, 2003 Figure 6-8 Repeater

16. ©Brooks/Cole, 2003 Repeaters operate at the first layer of the OSI model. Note:

17. ©Brooks/Cole, 2003 Figure 6-9 Bridge

18. ©Brooks/Cole, 2003 Bridges operate at the first two layers of the OSI model. Note:

19. ©Brooks/Cole, 2003 Figure 6-10 Switch

20. ©Brooks/Cole, 2003 Routers operate at the first three layers of the OSI model. Note:

21. ©Brooks/Cole, 2003 Figure 6-11 Routers in an internet

22. ©Brooks/Cole, 2003 Figure 6-12 Connecting devices and the OSI model Router 和 Gateway 現在不太區別了

23. ©Brooks/Cole, 2003 THE INTERNET ANDTCP/IP ANDTCP/IP 6.5

24. ©Brooks/Cole, 2003 Figure 6-13 TCP/IP and OSI model

25. ©Brooks/Cole, 2003 Figure 6-14 IP addresses in dotted-decimal notation

26. ©Brooks/Cole, 2003 Figure 6-15 Client-server model

27. ©Brooks/Cole, 2003 Figure 6-16 FTP

28. ©Brooks/Cole, 2003 Figure 6-17 SMTP

29. ©Brooks/Cole, 2003 Figure 6-18 Email address

30. ©Brooks/Cole, 2003 Figure 6-19 TELNET

31. ©Brooks/Cole, 2003 Figure 6-20 URL

32. ©Brooks/Cole, 2003 Figure 6-21 Browser

33. ©Brooks/Cole, 2003 Figure 6-22 Categories of Web documents