Chapter 1: Wide-Area Networking Basics
Defining wide-area networking
Explaining WAN connection types
Describing WAN protocol encapsulation methods
Introducing Cisco router cabling standards
Identifying AUX and COM port connectors
Understanding popular DSL technologies
Recognizing the differences between DCE and DTE devices
A wide-area network (WAN) is a connection between two or more local-area networks (LANs) spanning across a large, spread-out geographical area. A single LAN is usually considered to be confined to the same building or office that does not communicate over public transportation methods. A metropolitan-area network (MAN) limits its communications to a specific city function or campus area, while a WAN uses dedicated leased lines from telephone companies to establish links between geographically dispersed LANs and/or MANs. WAN technologies are generally represented by the three lower layers of the OSI model, namely, the network, data link, and physical layers.
The Internet is the best example of a WAN and is the largest public network on the planet. As you can see in Figure 1-1, private WANs are used to establish permanent communications links between company sites and branch offices. Using routers, traffic is managed and sent to the proper destination LAN. The traffic is then transferred to LAN switching devices until the data reaches the intended recipient. Private WANs may use a number of methods to connect to remote sites, ...