TAILIEUCHUNG - Lecture Data communications and networking: Chapter 9 - Behrouz A. Forouzan

Chapter 9 - Using telephone and cable networks for data transmission. This chapter shows how the issues discussed in the previous chapters can be used in actual networks. In this chapter, we first discuss the telephone network as designed to carry voice. We then show how it can be used to carry data. Second, we discuss the cable network as a television network. We then show how it can also be used to carry data. | Chapter 9 Using Telephone and Cable Networks for Data Transmission Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 9. 9-1 TELEPHONE NETWORK Telephone networks use circuit switching. The telephone network had its beginnings in the late 1800s. The entire network, which is referred to as the plain old telephone system (POTS), was originally an analog system using analog signals to transmit voice. Major Components LATAs Signaling Services Provided by Telephone Networks Topics discussed in this section: 9. Figure A telephone system 9. Intra-LATA services are provided by local exchange carriers. Since 1996, there are two types of LECs: incumbent local exchange carriers and competitive local exchange carriers. Note 9. Figure Switching offices in a LATA 9. Figure Point of presences (POPs) 9. The tasks of data transfer and signaling are separated in modern telephone networks: data transfer is done by one network, signaling by another. Note 9. Figure Data transfer and signaling networks 9. Figure Layers in SS7 9. 9-2 DIAL-UP MODEMS Traditional telephone lines can carry frequencies between 300 and 3300 Hz, giving them a bandwidth of 3000 Hz. All this range is used for transmitting voice, where a great deal of interference and distortion can be accepted without loss of intelligibility. Modem Standards Topics discussed in this section: 9. Figure Telephone line bandwidth 9. Modem stands for modulator/demodulator. Note 9. Figure Modulation/demodulation 9. Figure The and constellation and bandwidth 9. Figure Uploading and downloading in 56K modems 9. 9-3 DIGITAL SUBSCRIBER LINE After traditional modems reached their peak data rate, telephone companies developed another technology, DSL, to provide higher-speed access to the Internet. Digital subscriber line (DSL) technology is one of the most promising for supporting high-speed

• Quản trị mạng
• Data communications
• Lecture Data communications
• Physical layer
• Data link layer
• Telephone network
• Dial up modems
• Business data communications
• Network criteria
• Data communications system
• Data communications networks
• Media access control
• Network models
• Network standards
• Application layer
• Application architectures
• Digital transmission
• Network and transport layers
• Transport layers
• Local area networks
• Traditional ethernet
• Wireless local area networks
• Wireless LANs
• Backbone networks
• Backbone network architectures
• Circuit switched networks
• Wide area networks
• Network security
• Risk assessment
• Network design
• Traditional network design
• Network management
• Configuration management