Chapter 6

Module 6A Telecommunications Module 6B Networks Chapter 6

Telecommunications Understanding the Telephone System Modems: From Digital to Analog & Back Digital Telephony: Living with Twisted Pair Alternatives to Digital Telephony Convergence: Is It a Phone or a Computer? Module A

Understanding the Telephone System Telecommunications Understanding the Telephone System Module A Public switched telephone network (PSTN) analog system based on standards that date back more than a century Learn more about the PSTN and fast-breaking new telecommunications technologies? PhoneZone.com’s tutorials.

Understanding the Telephone System Telecommunications Understanding the Telephone System Quality of Service (QoS) Local Exchange Carriers (LECs) local access & transport area (LATA) twisted pair local loop Module A Fiber Optics Online is a trade journal specializing in fiber optics industry; this is a great site to learn about new technologies.

Long-Distance Transmission Media Telecommunications Long-Distance Transmission Media If you place a call outside the local transport area, an interchange carrier (IXC)—a long-distance telephone company—comes into play Module A Transmission facilities copper wire fiber-optic cables microwaves satellites Fiber optic cables consist of thin strands of glass that transmit data by means of pulses of light.

Standards and Regulations Telecommunications Standards and Regulations Standards International Telecommunications Union (ITU) Universal service Common carrier immunity Deregulation Regional Bell Operating Companies (RBOCs) Module A The home page of Pacific Bell, a RBOC, is packed with information and tutorials about cutting-edge telecommunications services.

More Ways to Access the System Telecommunications More Ways to Access the System Private Branch Exchange (PBX) Cellular telephones Leased lines Module A Cellular telephones enable subscribers to place calls via a wireless communications system.

The PSTN in Perspective Telecommunications The PSTN in Perspective Module A Sender of call receiver of call As a caller moves from one area to another, a new cell site steps in to keep the signal strong. The sites are connected to a Mobile Telephone Switching Office (MTSO), which is connected to the standard PSTN telephone system.

Modems: From Digital to Analog & Back Telecommunications Modems: From Digital to Analog & Back Telephone lines use analog transmission receiver sender Module A Modem 2 Modem 1 How modems work modulation demodulation internal modem external modem A modem transforms the computer's digital signals into analog tones that can be conveyed through the telephone system.

Modems: From Digital to Analog & Back Telecommunications Modems: From Digital to Analog & Back Asynchronous Communication asynchronous: used by modems synchronous Modulation Protocols data transfer rate bits per second (bps) V.90 maximum rate of 56 Kbps V.34 maximum rate of 28800 bps fall back Module A

Telecommunications Fax Module A Facsimile transmission enables you to send an image of a document over the telephone lines to anyone who has a fax machine. If your computer has a fax modem, you can send and receive faxes from your computer.

Digital Telephony: Living with Twisted Pair Telecommunications Digital Telephony: Living with Twisted Pair Bandwidth measured in Kbps, Mbps, or Gbps Last mile technologies Integrated Services Digital Network (ISDN) Digital Subscriber Line (DSL) Synchronous Optical Network (SONET) Module A BellSouth is one of the first RBOCs to offer ADSL service. Follow the links to FastAccess to learn more.

Alternatives to Digital Telephony Telecommunications Alternatives to Digital Telephony Direct Broadcast Satellite (DBS) Cable Modems coaxial cable Electrical Power Systems Module A In contrast to twisted pair, it’s easy to achieve very high bandwidth data communication with coaxial cable.

Convergence: Is It a Phone or a Computer Telecommunications Convergence: Is It a Phone or a Computer Digitization enables convergence, a process of technological “morphing” in which previously distinct devices lose their sharply-defined boundaries, and blend together. Module A

Convergence: Is It a Phone or a Computer? Telecommunications Convergence: Is It a Phone or a Computer? The everything PC TV Internet set-tops Personal Communication Service (PCS) Internet telephony Internet faxing Module A WebTV allows you to access the Internet using your television set as a display. Visit their web site for more information.

Networks Introducing Computer Networks Network Fundamentals Local Area Networks (LANs) Wide Area Networks (WANs) Module B

Introducing Computer Networks: Synergy at Work What is a computer network? Types of computer networks: LANs & WANs local area network metropolitan area network wide area network Networking synergies in a nutshell reducing hardware costs enabling shared applications building massive information resources connecting people Module B

Introducing Computer Networks: Synergy at Work Module B Computer networks enable users to share software and to create common pools of data.

Network Fundamentals Physical media Switching & routing techniques Networks Network Fundamentals Physical media Switching & routing techniques circuit switching packet switching which is best Module B

Network Fundamentals Protocols Network layers proprietary protocols Networks Network Fundamentals Protocols proprietary protocols open protocols protocol suite Network layers the protocol stack Module B stack protocol layers A message starts at the "top" of a stack of layers and moves down through the various layers (protocol stack) until it reaches the "bottom" or physical media.

Local Area Networks (LANs): Limited Reach, Fast Connections Keyboard & monitor for server Module B Computer 3 Personnel Computer 4 Server - Daily sales Computer 2 Accounting Computer 1 Sales & marketing Laser printer LANs transform an organization's hardware into what seems to users like one gigantic computer system.

Local Area Networks (LANs): Limited Reach, Fast Connections Networking hardware: Network Interface Cards (NICs) workstation node Networking software peer-to-peer networks client/server networks Clients Module B

Local Area Networks (LANs): Limited Reach, Fast Connections Media twisted pair coaxial cable fiber-optic cable infrared radio LAN topologies bus (daisy chain) star ring Module B

Local Area Networks (LANs): Limited Reach, Fast Connections Module B Most networks use a bus, star, or ring topology.

By far the most popular LAN standard is Ethernet Networks LAN Technologies Module B By far the most popular LAN standard is Ethernet Like to know the latest news about LANs? Check out LAN Times, the premiere LAN trade journal Like to learn more about the Ethernet? Check out Charles Spurgeon’s Ethernet Web Site which covers all the Ethernet technologies used today and includes a practical guide for do-it-yourselfers.

LAN Protocals AppleTalk IPX/SPX NetBEUI TCP/IP B Networks LAN Protocals AppleTalk IPX/SPX NetBEUI TCP/IP Module B Like AppleTalk, TCP/IP can be used with a variety of lower- level protocols, such as Ethernet. A LAN that uses TCP/IP is called an intranet, a term that suggests that it’s an Internet designed for internal use within an organization.

Wide Area Networks (WANs): Long-Haul Carriers WANs are like long-distance telephone systems Module How WANs work Point of Presence (POP) backbones B The Internet is a WAN of massive proportions. Backbone provider UUNET offers local access from more than 1,000 locations worldwide.

Wide Area Networks (WANs): Long-Haul Carriers How WANs are organized public data network (PDN) virtual private network (VPN) WAN protocals oldest is X.25 WAN Applications LAN-LAN connections transaction acquisition electronic data interchange (EDI) Module B To explore cutting-edge WAN technologies such as SDMS and ATM, a good place to start is Pacific Bell’s FasTrak Data and Video Services page