Chapter 6 Telecommunications & Networks

Communication Model Message is communicated via a signal Transmission medium (communication channel) “carries” the signal Feedback Encode Decode Chapter 6 IS for management

Telecommunications Electronic transmission of signals, e.g., telephone, radio, television Telecommunication medium: Anything that carries an electronic signal & interfaces between a sending device & a receiving device Data Communications: A subset of telecommunications referring to the sending, transmission, & receiving of data -- typically between computer systems Chapter 6 IS for management

Communications & Telecommunications In human speech, signals are transmitted through the air; in telecommunications, signals are transmitted through various media Chapter 6 IS for management

Elements of Telecommunications Chapter 6 IS for management

Types of telecommunication Media (1) Twisted Pair Insulated copper wire Electrical signals Coaxial Cable Inner wire core surrounded by shielding Higher transmission speeds than twisted pair Fiber-optic Cable Extremely thin strands of glass bound together Light pulse signals Very high transmission speeds Chapter 6 IS for management

Types of Telecommunication Media (2) Microwave Satellite Chapter 6 IS for management

Types of Telecommunication Media (3) Cellular transmission signals are transmitted to receivers & integrated into the regular network. Chapter 6 IS for management

Modems Translate digital signals to analog for transmission over the Public Switched Telephone Network (PSTN) Chapter 6 IS for management

Carriers & Services (1) Common Carriers: Long distance telephone companies (AT&T, Sprint) Value-Added Carriers: Private telecom systems offering enhanced services for a fee Switched Lines: Circuits that use switching equipment to allow one device to connect to other devices (typical phone lines) Dedicated Lines: Point-to-point circuits with no switching or dialing Chapter 6 IS for management

Carriers & Services (2) Private Branch Exchange (PBX) Telecommunications switching equipment that allows users within an organization to share outside lines Capable of handling both voice & data traffic Integrated Services Digital Network (ISDN) Uses existing telecommunications infrastructure to simultaneously transmit digital voice, data, & video Being phased out in North America (cable & ADSL are replacing this service) T1 Circuits High speed dedicated lines (1.54 Mbps) Equivalent to 24 regular voice lines Chapter 6 IS for management

Types of Network Configurations Ring Bus Hierarchical Star Chapter 6 IS for management

LANs & WANs Local Area Network (LAN): Connects computer systems & devices in the same geographic area (can be ring, bus, hierarchical, star, hybrid) Wide Area Network (WAN): Ties together large geographic regions using microwave & satellite transmission or telephone lines International Network (Global Area Network: GAN): Links systems between countries Chapter 6 IS for management

Types of Computing Connectivity (1) Terminal-to-Host Applications & databases reside on host mainframe computer User accesses applications via a “dumb” terminal File Server File server transfers data & programs to PCs on the network where the PCs perform most processing. “Dumb” terminal Chapter 6 IS for management

Types of Computing Connectivity (2) Client/Server Applications & databases reside on specialized host computers (servers) Processing is shared between the host server & the client Client & server may be different types of computers Chapter 6 IS for management

Advantages & Disadvantages of Client/Server Computing Reduced costs Improved performance Increased security Disadvantages Increased costs Loss of control Complex multi-vendor environment Chapter 6 IS for management

Communication Software Communications Software: Provides error checking, message formatting, communication logs, data security/privacy, & translation capabilities for networks Network Operating System (NOS): Systems software that controls the devices on a network & allows them to communicate with each other Network Management Software: Monitors the use of network resources, scans for viruses, & ensures compliance with software licenses Chapter 6 IS for management

Communication Protocols Protocol: Rules that ensure communications among different types of computers from multiple manufacturers Open Systems Interconnection (OSI): Leading protocol “model”; comprised of 7 layers Transmission Control Protocol/Internet Protocol (TCP/IP): Two communication protocols of the Internet that work together (rapidly overtaking OSI) Systems Network Architecture (SNA): IBM’s proprietary communication protocol Ethernet: Protocol standard developed for LANs using a bus topology X.400 & X.500: Standards for message handling & network directories Chapter 6 IS for management

Bridges, Routers, Gateways, & Switches Bridge: Connects two or more networks that use the same protocol at the media control sublayer of the data link layer Router: Operates at the network level of the OSI model with more sophisticated addressing software than bridges; can determine preferred paths Gateway : Operates at or above the OSI transport layer & links LANs or networks that employ different architectures & use dissimilar protocols Switch: Switches data to its destination by a point-to-point (rather than shared) connection Chapter 6 IS for management

Telecommunications Applications (1) Linking computers & data terminals: Download & upload information Voice Mail: Enables users to send, receive, & save verbal messages, including sending the same message to a “group” E-mail: Enables users to send, receive, & save text messages & attached documents Telecommuting: Enables employees to work away from the office using PCs & networks to communicate electronically Chapter 6 IS for management

Telecommunications Applications (2) Videoconferencing Allows participants to conduct long-distance meetings “face to face” while eliminating travel Chapter 6 IS for management

Telecommunications Applications (3) Electronic Data Interchange (EDI) Uses networks to allow output from one organization’s system to be processed directly as input to another organization’s systems, without human intervention; follows standards & procedures Chapter 6 IS for management

Case: Nav Canada, pages 284-285 Next Class: Chapter 7 IS for management