Cisco® CCNA Exam Cram Notes : WAN Terms

V. WAN Technologies

1. WAN Terms

WANS are connected over serial lines that operate at lower speeds than LANs. Some of the WAN terms are:

1. Modems: Modems connect to public telephone circuits through dial-up.

2. CSU/DSU: Stands for Channel Service Unit / Data Service Unit. CSU/DSUs are used for connecting to Central Office of a Telephone switching company and provides serial WAN connections.

3. Multiplexors (mux): Multiplexors combine two or more signals before transmitting on a single channel. Multiplexing can be done by sharing "time" or "frequency".

4. CPE stands for Customer Premise Equipment. It is any terminal and associated equipment located at a subscriber's premises and connected with a carrier's telecommunication circuit at the demarcation point.

5. Demarc: Demarcation point between carrier equipment and CPE.

Typical WAN interfaces, that one come across frequently are:

EIA 232, EIA 449, EIA 530, V.35, and X.21. The Cisco router serial interface will be a 60-pin D-shell connector. This in turn is connected to service provider equipment, usually through a CSU/ DSU. Therefore, appropriate conversion cable need to be used when interfacing with a WAN device such a CSU/DSU. CSU/ DSU in turn is connected to the service provider through the cable supplied by the service provider.
























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CCNA Cram Notes Contents
  • I. Networking Fundamentals
  • II. Cisco IOS
    • 1. Cisco Router Architecture
    • 2. Cisco Router (25xx series) and its interfaces
  • III. Routing Technologies
  • IV. LAN Switching Technologies
  • V. WAN Technologies
  • VI. Network Access
  • VII. IP connectivity and Services
  • VIII. Security Fundamentals
  • IX. Automation and Programmability
  • X. Appendix
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