Telecommunications

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CHAPTER 4

• Telecommunications Networking

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TELECOMMUNICATIONS NETWORKING

• TELECOMMUNICATIONS Communications (both voice
  and data) at a distance
• NETWORKING Electronic linking of geographically
  dispersed devices

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THE NEED FOR NETWORKING

• SHARING OF TECHNOLOGY RESOURCES
• SHARING OF DATA
• DISTRIBUTED DATA PROCESSING AND CLIENT/SERVER
  SYSTEMS
• ENHANCED COMMUNICATIONS, INCLUDING ELECTRONIC
  DATA INTERCHANGE (EDI) AND ACCESS TO THE INTERNET

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KEY ELEMENTS OF TELECOMMUNICATIONS NETWORKING

• ANALOG SIGNALS Continuous waveform, passes thru
  system. Example voice communications
• DIGITAL SIGNALS Discrete waveform two discrete
  states (1-bit 0-bit, on / off pulse). Data
  communication. Uses modem to translate analog to
  digital, digital to analog

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MODEM

• ABBREVIATION FOR MODULATOR/ DEMODULATOR
• DEVICE THAT CONVERTS DATA FROM DIGITAL FORM TO
  ANALOG FORM TO BE SENT OVER ANALOG TELEPHONE
  NETWORK (RECONVERTS DATA AFTER IT HAS BEEN
  TRANSMITTED)

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SPEED OF TRANSMISSION

• BANDWIDTH Difference between highest and lowest
  frequencies (cycles per second) that can be
  transmitted on a particular medium a capacity
  measure
• HERTZ Cycles per second
• BAUD Signals sent per second
• BITS PER SECOND (bps) Common measure

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TYPES OF TRANSMISSION LINES

• PRIVATE, OR DEDICATED, LINES
• SWITCHED LINES
• SIMPLEX TRANSMISSION
• HALF-DUPLEX TRANSMISSION
• FULL-DUPLEX TRANSMISSION

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TRANSMISSION MEDIA

• TWISTED PAIR
• COAXIAL CABLE Baseband and broadband
• WIRELESS Cordless phone, cellular phone,
  wireless LAN, infrared devices
• SATELLITE Microwave, line of sight
• FIBER OPTICS

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ORBITING SATELLITES
MICROWAVE TRANSMISSION
UPLINK
DOWNLINK
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NEW SATELLITES

• OVER A DOZEN NEW PROJECTS PROPOSED
• LOW EARTH ORBIT (LEO) SATELLITES Only 400 to
  1000 miles above the earth, compared to
  geosynchronous satellites at 22,000 miles above
  the equator. 1,700 satellites to be launched by
  2006

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NEW SATELLITES

• IRIDIUM 66 satellites offered mobile telephony,
  paging, and data communications. Bankrupt by
  1999.
• TELEDESCIC Will include 288 LEO to provide
  low-cost, high-speed Internet access, networking,
  teleconferencing

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TELECOMMUNICATIONS TRANSMISSION SPEEDS

• Twisted pair - voice telephone 14.4 kbps -56 kbps
• Twisted pair - conditioned 56 kbps - 144 kbps
• Twisted pair - LAN 4 mbps - 100 mbps
• Coaxial cable - baseband 10 mbps - 2 gbps
• Coaxial cable - broadband 10 mbps - 550 mbps
• Radio frequency wireless LAN 1 mbps - 11 mbps
• Infrared light wireless LAN 4 mbps - 16 mbps
• Microwave / Satellite 64 kbps - 100 mbps
• Fiber optic cable 100 mbps - 100
  gbps

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TOPOLOGY OF NETWORKS

• BUS TOPOLOGY
• RING TOPOLOGY
• STAR TOPOLOGY
• TREE, OR HIERARCHICAL, TOPOLOGY
• MESH TOPOLOGY
• MORE COMPLEX TOPOLOGIES

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NETWORK TYPES

• COMPUTER TELECOMMUNICATIONS NETWORK
• PRIVATE BRANCH EXCHANGE (PBX) NETWORK
• LOCAL AREA NETWORK (LAN)

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NETWORK TYPES

• BACKBONE NETWORK
• WIDE AREA NETWORK (WAN)
• INTERNET

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LOCAL AREA NETWORKS

• CONTENTION BUS NETWORK Uses CSMA/CD protocol.
  Example Ethernet
• TOKEN BUS NETWORK Central to Manufacturing
  Automation Protocol (MAP)
• TOKEN RING NETWORK Used in LAN unidirectional
  data flow

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NEW LAN TECHNOLOGY

• FAST ETHERNET Ethernet operating at speeds up
  to 100 mbps
• FIBER DISTRIBUTED DATA INTERFACE (FDDI) Token
  ring architecture delivered on a dual ring at
  speeds up to 100 mbps

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BACKBONE NETWORKS

• MIDDLE DISTANCE NETWORKS Interconnect LANs in a
  single organization with each other and with the
  organizations WAN and Internet
• EMPLOY HIGH-END LAN TECHNOLOGY, OFTEN OPERATING
  AT 100 MBPS OR MORE

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BACKBONE NETWORK TERMINOLOGY

• HUB Simple device connecting one section of a
  LAN to another
• BRIDGE Connects two LAN segments when the LANs
  use the same protocols
• ROUTER, OR GATEWAY Connects two or more LANs
  together. Networks may use different protocols
• SWITCH Connects more than two LANs that use the
  same protocol into a backbone network

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WIDE AREA NETWORKS

• DIRECT DISTANCE DIALING (DDD)
• WIDE AREA TELEPHONE SERVICE (WATS)
• LEASED LINE Most common, T-1 lines
• SATELLITE C-Band, KU-Band
• VALUE ADDED NETWORK (VAN)
• INTEGRATED SERVICES DIGITAL NETWORK (ISDN)

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VALUE ADDED NETWORK (VAN)

• DATA-ONLY, PRIVATE, NONREGULATED
  TELECOMMUNICATIONS NETWORK Uses packet switching
• AN ORGANIZATION MAY CHOOSE TO BUY SERVICES OF A
  VAN TO IMPLEMENT ITS WIDE AREA NETWORK (WAN)

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PACKET SWITCHING

• INFORMATION DIVIDED INTO PACKETS OF SOME FIXED
  LENGTH, SENT OVER NETWORK SEPARATELY
• PERMITS MORE EFFICIENT USE OF THE NETWORK

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INTEGRATED SERVICES DIGITAL NETWORK (ISDN)

• EMERGING SET OF INTERNATIONAL STANDARDS
• USING PUBLIC TELEPHONE NETWORK
• EXTENSIVE NEW TELECOMMUNICATIONS CAPABILITIES
• SIMULTANEOUS TRANSMISSION OF VOICE AND DATA OVER
  SAME LINE TO TELEPHONE USERS WORLDWIDE

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USES OF ISDN

• CUSTOMER SERVICE APPLICATION Customers records
  automatically sent to service representatives
  workstation when customer calls in
• SOLVES DIAL-IN PROBLEMS INTO CORPORATE NETWORK
  FOR TELECOMMUTERS, BRANCH OFFICES

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NEW WAN AND LAN TECHNOLOGY

• ASYNCHRONOUS TRANSFER MODE (ATM) Switching
  technology employing fast packet switching.
  Emerging standard for broadband ISDN. Speeds from
  1.544 mbps to 622 mbps. Represents the future for
  both LANs and WANs

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PROTOCOL

• RULES PROCEDURES
• TO GOVERN TRANSMISSION
• BETWEEN COMPONENTS
• IN A NETWORK

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NETWORK PROTOCOLS

• OPEN SYSTEMS INTERCONNECTION (OSI) Reference
  model, emerging standard
• TRANSMISSION CONTROL PROTOCOL / INTERNET PROTOCOL
  (TCP/IP) Standard used on the Internet
• SYSTEMS NETWORK ARCHITECTURE (SNA) IBM standard
• FILE TRANSFER PROTOCOL (FTP) Allows file
  transfer on Internet

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INTERNET

• NETWORK OF NETWORKS THAT USE THE TCP/IP PROTOCOL,
  WITH GATEWAYS (CONNECTIONS) TO OTHER NETWORKS
  THAT DO NOT USE TCP/IP
• INTERNET APPLICATIONS e-mail, Usenet newsgroups,
  listserv, FTP, Gopher, Archie, Veronica, World
  Wide Web

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CONNECTIONS TO INTERNET

• PHONE LINE MODEM
• CABLE MODEM
• DIGITAL SUBSCRIBER LINE (DSL)
• T-1 DATA PHONE LINE
• SATELLITE
• FIBER OPTICS

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INTRANET

• A NETWORK OPERATING WITHIN AN ORGANIZATION
  EMPLOYING TCP/IP PROTOCOL
• ORGANIZATION USES SAME WEB BROWSER, CRAWLER,
  SERVER SOFTWARE AS IT WOULD ON THE INTERNET, BUT
  INTRANET IS NOT ACCESSIBLE FROM OUTSIDE THE
  ORGANIZATION

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CONNECTIVITY

• MEASURE OF ABILITY OF COMPUTING DEVICES TO PASS
  SHARE INFORMATION WITHOUT HUMAN INTERVENTION
• OPEN SYSTEMS Software able to function on
  different computer platforms. Nonproprietary
  operating systems, applications, protocols

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INTERNET 2

• WILL REPLACE INTERNET
• LEADING-EDGE NETWORK CAPABILITY
• HIGH-PERFORMANCE APPLICATIONS
• RAPID TRANSFER OF SERVICES, APPLICATIONS TO
  BROADER INTERNET COMMUNITY

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CHAPTER 4

• Telecommunications Networking