Chapter 4: Chapter 4: Telecommunications and Telecommunications and

NetworkingNetworking

Telecommunications & Telecommunications & NetworkingNetworking

TelecommunicatioTelecommunications - ns - communications communications (both voice and (both voice and data) at a distance data) at a distance

Networking - the Networking - the electronic linking electronic linking of geographically of geographically dispersed devicesdispersed devices

The Need for NetworkingThe Need for Networking

Sharing of technology resourcesSharing of technology resources Sharing of dataSharing of data Distributed data processing and Distributed data processing and

client/server systemsclient/server systems Enhanced communications, Enhanced communications,

including Electronic Data including Electronic Data Interchange (EDI) and access to the Interchange (EDI) and access to the InternetInternet

Telecommunications & Telecommunications & Networking: The Big Networking: The Big PiecesPieces Analog vs. digital Analog vs. digital

signalssignals MediaMedia TopologyTopology Network typesNetwork types ProtocolsProtocols

ModemModem

An abbreviation for An abbreviation for momodulator/ dulator/ demdemodulatorodulator

A device that converts data from A device that converts data from digital form to analog form so that digital form to analog form so that it can be sent over the analog it can be sent over the analog telephone network (as well as telephone network (as well as reconverts data after it has been reconverts data after it has been transmitted)transmitted)

Speed of Transmission Speed of Transmission

bandwidth - difference between highest bandwidth - difference between highest and lowest frequencies (cycles per and lowest frequencies (cycles per second) that can be transmitted on a second) that can be transmitted on a particular medium - a capacity particular medium - a capacity measuremeasure

Hertz - cycles per secondHertz - cycles per second baud - signals sent per secondbaud - signals sent per second common measure - bits per second common measure - bits per second

(bps)(bps)

Types of Transmission Types of Transmission LinesLines Private, or dedicated linesPrivate, or dedicated lines Switched lines Switched lines

-------------------------------------------------------------------------- Simplex transmissionSimplex transmission Half-duplex transmissionHalf-duplex transmission Full-duplex transmissionFull-duplex transmission

Transmission MediaTransmission Media

Twisted pair Twisted pair Coaxial cable - baseband and Coaxial cable - baseband and

broadbandbroadband Wireless, including microwave , Wireless, including microwave ,

radio frequency, infrared lightradio frequency, infrared light Satellite Satellite Fiber opticsFiber optics

New SatellitesNew Satellites

Over a dozen new projects proposedOver a dozen new projects proposed 1,700 satellites to be launched in the 1,700 satellites to be launched in the

next ten years, compared to the next ten years, compared to the present 150 commercial satellitespresent 150 commercial satellites

Low earth orbit (LEO) satellites - only Low earth orbit (LEO) satellites - only 400 to 1000 miles above the earth, 400 to 1000 miles above the earth, compared to geosynchronous compared to geosynchronous satellites at 22,000 miles above the satellites at 22,000 miles above the equatorequator

New Satellites (continued)New Satellites (continued)

Iridium -- 66 satellites to offer Iridium -- 66 satellites to offer mobile telephony, paging, and mobile telephony, paging, and data communications (Motorola, data communications (Motorola, Lockheed Martin, Sprint)Lockheed Martin, Sprint)

Loral’s Globalstar - 48 satellites, Loral’s Globalstar - 48 satellites, similar services to Iridiumsimilar services to Iridium

New Satellites (continued)New Satellites (continued)

Teledesic - 840 Teledesic - 840 satellites, Internet satellites, Internet access, corporate access, corporate networking, networking, desktop desktop videoconferencinvideoconferencing (Craig McCaw, g (Craig McCaw, Bill Gates) Bill Gates)

Telecommunications Telecommunications Transmission SpeedsTransmission Speeds Twisted pair - voice telephoneTwisted pair - voice telephone 14,400 bps -14,400 bps -

56,000 bps56,000 bps Twisted pair - conditionedTwisted pair - conditioned 56 kbps - 144 kbps56 kbps - 144 kbps Twisted pair - LANTwisted pair - LAN 4 mbps - 100 mbps4 mbps - 100 mbps Coaxial cable - basebandCoaxial cable - baseband 10 mbps - 264 mbps10 mbps - 264 mbps Coaxial cable - broadbandCoaxial cable - broadband 10 mbps - 550 mbps10 mbps - 550 mbps Radio frequency wireless LANRadio frequency wireless LAN 2 mbps - 8 mbps2 mbps - 8 mbps Infrared light wireless LANInfrared light wireless LAN 4 mbps - 16 mbps4 mbps - 16 mbps Microwave / SatelliteMicrowave / Satellite 64 kbps - 50 mbps64 kbps - 50 mbps Fiber optic cableFiber optic cable 100 mbps - 30 gbps100 mbps - 30 gbps

Topology of NetworksTopology of Networks

Bus topologyBus topology Ring topologyRing topology Star topologyStar topology Tree, or hierarchical, topologyTree, or hierarchical, topology Mesh topologyMesh topology More complex topologiesMore complex topologies

Network TypesNetwork Types

Computer telecommunications Computer telecommunications networknetwork

Private branch exchange (PBX) Private branch exchange (PBX) networknetwork

Local area network (LAN)Local area network (LAN) Backbone networkBackbone network Wide area network (WAN)Wide area network (WAN) InternetInternet

Local Area NetworksLocal Area Networks

Contention bus network (e.g., Contention bus network (e.g., Ethernet) - uses CSMA/CD protocolEthernet) - uses CSMA/CD protocol

Token bus networkToken bus network Token ring networkToken ring network

New LAN TechnologyNew LAN Technology

Fast EthernetFast Ethernet: Ethernet : Ethernet (contention bus) operating at (contention bus) operating at speeds up to 100 mbps speeds up to 100 mbps

Fiber Distributed Data Interface Fiber Distributed Data Interface (FDDI):(FDDI): Token ring architecture Token ring architecture delivered on a dual ring at speeds delivered on a dual ring at speeds up to 100 mbpsup to 100 mbps

Backbone NetworksBackbone Networks

Middle distance networks that Middle distance networks that interconnect LANs in a single interconnect LANs in a single organization with each other and organization with each other and with the organization’s WAN and with the organization’s WAN and the Internetthe Internet

Employ high-end LAN technology, Employ high-end LAN technology, often operating at 100 mbps or often operating at 100 mbps or moremore

Backbone Network Backbone Network TerminologyTerminology

Hub - simple Hub - simple device connecting device connecting one section of a one section of a LAN to anotherLAN to another

Bridge - connects Bridge - connects two LAN two LAN segments when segments when the LANs use the the LANs use the same protocolssame protocols

Backbone Network Backbone Network TerminologyTerminology(continued)(continued) Router, or gateway - connects two Router, or gateway - connects two

or more LANs together; networks or more LANs together; networks may use different protocols may use different protocols

Switch - connects more than two Switch - connects more than two LANs that use the same protocol LANs that use the same protocol into a backbone networkinto a backbone network

Wide Area NetworksWide Area Networks

Direct Distance Dialing (DDD)Direct Distance Dialing (DDD) Wide Area Telephone Service (WATS)Wide Area Telephone Service (WATS) Leased line (most common, T-1 lines)Leased line (most common, T-1 lines) Satellite (C-band, KU-band)Satellite (C-band, KU-band) Value added network (VAN)Value added network (VAN) Integrated Services Digital Network Integrated Services Digital Network

(ISDN)(ISDN)

Value Added Network, or Value Added Network, or VANVAN A data-only, private, nonregulated A data-only, private, nonregulated

telecommunications network that telecommunications network that uses packet switchinguses packet switching

An organization may choose to buy An organization may choose to buy the services of a VAN to implement the services of a VAN to implement its wide area network (WAN)its wide area network (WAN)

Packet SwitchingPacket Switching

A method of operating a digital A method of operating a digital telecommunications network in telecommunications network in which information is divided into which information is divided into packets of some fixed length that packets of some fixed length that are then sent over the network are then sent over the network separatelyseparately

Permits more efficient use of the Permits more efficient use of the networknetwork

ISDN - Integrated Services ISDN - Integrated Services Digital NetworkDigital Network An emerging set of international An emerging set of international

standards by which the public standards by which the public telephone network will offer telephone network will offer extensive new telecommunications extensive new telecommunications capabilities - including capabilities - including simultaneous transmission of voice simultaneous transmission of voice and data over the same line - to and data over the same line - to telephone users worldwidetelephone users worldwide

ISDN - Integrated Services ISDN - Integrated Services Digital NetworkDigital Network Offered over twisted pair wiring - Offered over twisted pair wiring -

“B” or bearer channels, “D” or data “B” or bearer channels, “D” or data channelschannels

Basic rate - two B channels of 64 kbps Basic rate - two B channels of 64 kbps (thousand bits per second), one 16 kbps (thousand bits per second), one 16 kbps D channel - all over one twisted pairD channel - all over one twisted pair

Primary rate - 23 B channels of 64 kbps, Primary rate - 23 B channels of 64 kbps, one 64 kbps D channel - all over two one 64 kbps D channel - all over two twisted pairstwisted pairs

ISDN - UsesISDN - Uses

Customer service application - Customer service application - customer’s records automatically customer’s records automatically sent to service representative’s sent to service representative’s workstation when a customer calls inworkstation when a customer calls in

Economical and efficient way to Economical and efficient way to solve dial-in headaches into a solve dial-in headaches into a corporate network for corporate network for telecommuters, branch officestelecommuters, branch offices

New WAN and LAN New WAN and LAN Technology Technology Asynchronous Transfer Mode Asynchronous Transfer Mode

(ATM)(ATM): Switching technology : Switching technology employing fast packet switching; an employing fast packet switching; an emerging standard for broadband emerging standard for broadband ISDN, with speeds from 1.544 mbps ISDN, with speeds from 1.544 mbps up to 622 mbps; many up to 622 mbps; many prognosticators believe that ATM prognosticators believe that ATM represents the future for both LANs represents the future for both LANs and WANsand WANs

InternetInternet

Network of networks that use the Network of networks that use the TCP/IP protocol, with gateways TCP/IP protocol, with gateways (connections) to even more (connections) to even more networks that do not use TCP/IPnetworks that do not use TCP/IP

Internet applications - e-mail, Internet applications - e-mail, Usenet newsgroups, listserv, FTP, Usenet newsgroups, listserv, FTP, Gopher, Archie, Veronica, World Gopher, Archie, Veronica, World Wide WebWide Web

IntranetIntranet

A network operating within an A network operating within an organization which employs the organization which employs the TCP/IP protocolTCP/IP protocol

The organization uses the same Web The organization uses the same Web browser, Web crawler, and Web browser, Web crawler, and Web server software as it would on the server software as it would on the Internet, but the intranet is not Internet, but the intranet is not accessible from outside the accessible from outside the organizationorganization

Network ProtocolsNetwork Protocols

An agreed-upon set An agreed-upon set of rules or of rules or conventions conventions governing governing communications communications among elements of among elements of a network (or, to a network (or, to be more precise, be more precise, among layers or among layers or levels of a network)levels of a network)

Network ProtocolsNetwork Protocols

OSI (Open Systems Interconnection) OSI (Open Systems Interconnection) Reference Model - an emerging Reference Model - an emerging standardstandard

TCP/IP (Transmission Control TCP/IP (Transmission Control Protocol/Internet Protocol) - standard Protocol/Internet Protocol) - standard used on the Internet and IU networkused on the Internet and IU network

SNA (Systems Network Architecture) - SNA (Systems Network Architecture) - an IBM standardan IBM standard

Changing Nature of Changing Nature of Telecommunications/NetwTelecommunications/Networkingorking Decreasing price/performance ratio Decreasing price/performance ratio

-- faster transmission, cheaper -- faster transmission, cheaper More wireless optionsMore wireless options Increased standardizationIncreased standardization Increased usage of TCP/IP protocolIncreased usage of TCP/IP protocol Greater management complexity due Greater management complexity due

to anytime/anywhere access and to anytime/anywhere access and supportsupport