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CCNA 1 and 2 Companion Guide, Revised (Cisco Networking Academy Program) part 55

Cisco Networking Academy Program CCNA 1 and 2 Companion Guide, Revised part 55 is the Cisco approved textbook to use alongside version 3.1 of the Cisco Networking Academy Program CCNA 1 and CCNA 2 web-based courses. The topics covered provide you with the necessary knowledge to begin your preparation for the CCNA certification exam (640-801, or 640-821 and 640-811) and to enter the field of network administration. | chpt_10.fm Page 510 Tuesday May 27 2003 8 57 AM Objectives Upon completion of this chapter you will be able to Identify different types of WAN connections encapsulations and protocols Know the difference between a WAN and LAN and which type of addresses each uses chpt_10.fm Page 511 Tuesday May 27 2003 8 57 AM Chapter 10 WANs and Routers In this chapter you learn about WAN devices technologies and standards. In addition you learn about the function of a router in a WAN. Please be sure to look at this chapter s e-Labs Videos and PhotoZooms that you will find on the CD-ROM accompanying this book. These CD elements are designed to supplement the material and reinforce the concepts introduced in this chapter. WAN Characteristics A wide-area network WAN is a data communications network that extends across a large geographic area. WANs often use transmission facilities provided by common carriers for example telephone companies. A WAN differs from a local-area network LAN in several ways. For example unlike a LAN which connects workstations peripherals terminals and other devices in a single building or other small geographic area a WAN makes data connections across a broad geographic area. Companies use a WAN to connect various company sites so that information can be exchanged between distant offices. A WAN operates at the physical layer Layer 1 and the data link layer Layer 2 of the OSI reference model. It interconnects LANs that are usually separated by large geographic areas. WANs provide for the exchange of data packets frames between routers switches and the LANs they support. Table 10-1 lists some CPU information indicative of specific examples of data .