Introduction One major characteristic of a WAN is that the network operates beyond the local LAN's geographic scope. It uses the services of carriers such as regional Bell operating companies (RBOCs), Sprint, and MCI.
WANs use serial connections of various types to access bandwidth over wide-area geographies. By definition, the WAN connects devices separated by wide areas. WAN devices include the following:
Routers, which offer many services, including internetworking and WAN interface ports. Switches, which connect to WAN bandwidth for voice, data, and video communication. Modems, which interface voice-grade services; channel service units/digital service units. (CSU/DSUs) that interface Tl/EI services; and Terminal Adapters/Network Termination 1. TA/NT 1s) that interface Integrated Services Digital Network (ISDN) services. Communication servers which concentrate on dial-in and dial-out user communication.
Concept Questions
Demonstrate your knowledge of these concepts by answering the following questions in the space provided.
A WAN is used to interconnect local-area networks (LANs) that are typically separated by a large geographic area.
A WAN operates at the OSI reference model physical and data link layers.
The WAN provides for the exchange of data packets/frames between routers/bridges and the LANs that they support. Draw a WAN that includes three LANs.
Compare and contrast WANs and LANs layer by layer.