Networks and Networking Chapter 4 Copyright Prentice-Hall, Inc. 2001

6-2 Get Wired!! MonthlyTechnologyUpdate Surfing Online Books

6-3 What is it all about? Computer networks simply enhance the efficiency and effectiveness of interactions between people, whether they are knowledge workers or Internet surfers.

6-4 Digital Convergence l DVDs l Telephones l Televisions l Computers l Newspapers l College courses l Textbooks on CD-ROM l Banking/Finance Becoming digitally compatible!!

6-5 Connectivity Seeking ways to interface, or connect, a diverse set of hardware, software, and databases.

6-6 Cooperative Processing l E-commerce (electronic commerce) l Intercompany Networking l Electronic Data Interchange (EDI) l Intranets l Extranets

6-7 Data Communications Data Communications l Data Communications = Telecommunications l Special hardware transmits the digital information between computers

6-8 Data Communications Hardware Data Communications Hardware l Modem u Digital to Analog to Digital u Internal & External u Fax Modems l Network Interface Cards (NIC) l Special Function Communications Devices l Routers (backbone hardware)

6-9 Data Communications Messaging Data Communications Messaging l Message is distributed among: u Host or Server computer - in control u Front-end Processor - establishes handshake u Multiplexor - collects data from multiple devices and sends it along l Network Address

6-10 Serendipitous Surfing: Government Communications Protocols l Rules that govern the way data are transmitted l Communication between networks using incompatible protocols (use of routers)

6-11 Data Communications Channel The medium through which digital information must pass to get from one location in a computer network to the next. The medium through which digital information must pass to get from one location in a computer network to the next. Also called the Line, Link or Pipe Transmission Media

6-12 Transmission Media l Wires & Wireless Media l Channel Capacity (Bandwidth) l Bits per Second (BPS) vs. Baud l Types: u Twisted-Pair Wire u Coaxial Cable u Fiber Optic Cable u High-Speed Wireless Transmission Media

6-13 Twisted-Pair Wire l Carries data as electrical signals l POTS (plain old telephone service) 56 K bps l ISDN - Line & Modem 128 K bps l ADSL - Line & Modem 1.5 to 9 M bps u Downstream rate u Upstream rate u Will compete with cable Transmission Media

6-14 Coaxial Cable l Carries data as electrical signals l Hundreds of times faster than POTS l 100 times faster than ISDN l Need a cable modem

6-15 Fiber Optic Cable l Carries data as laser- generated pulses of light l Foundation transmission medium for Internet backbone l Better for data security Courtesy of International Business Machines Corporation

6-16 High-Speed Wireless l Carries data via microwave or radio signals l Geosynchronous Orbit Satellites l Wireless Transceivers

6-17 Common Carriers l AT&T, MCI, Sprint, etc. l Private Line (or Leased Line) l Switched Line (or Dial-Up Line)

6-18 Is it time to GO yet?

6-19 Network Topologies Network Topology is a description of the possible physical connections within a network. It is a configuration of hardware and it shows which pairs of nodes can communicate. Networks

6-20 Network Topologies Networks Star Ring Bus

6-21 Client/Server Computing l Centralized Computing l Trend to Decentralizing & Downsizing u Server Computer u Client Computer u Proxy Server Computer u Front-end Applications u Back-end Applications

6-22 Network Line Control l Communications Protocols (TCP/IP) l Two Classifications: u Asynchronous Transmission (low speed) u Synchronous Transmission (high speed)

6-23 Types of Networks Wide Area Network WAN Metropolitan Area Network MAN Local Net LAN Tiny Area Network TAN

6-24 Sharing Resources on a LAN l Applications software l Links to mainframes l Communications capabilities l I/O devices l Storage devices l Add-on boards

6-25 Local Area Networks l l LAN Access Methods u u Token Access Method u u Ethernet l l LAN Servers u u File Server u u Print Server u u Communications Server

6-26 LAN Software l Operating Systems u Peer to Peer LANs u LANs with dedicated servers l Applications Software u Shared software u Groupware l Networks on the Fly

End of Chapter 4 Copyright Prentice-Hall, Inc Interactive Study Guide