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 EDI and access
  to the Internet

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Telecommunications Network Basic Components
Modems, switches, routers
Host computers Front-end processors Network
servers
Copper wires, coaxial cables, fiber optical
cables Microwave systems, communications
satellites
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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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How a Modem Works
Modem Modulates a digital signal into an analog
signal for transmission via analog medium, then
demodulates the signal into digital for receiving.
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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-Duples 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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Types of Telecommunications Media Twisted Pair
Wire Cable Coaxial Cable

• Twisted Pair Wire Cable
• Insulated pairs of wires historically used in
  telephone service and to connect computer
  devices.
• Coaxial Cable
• Consists of an inner conductor wire surrounded by
  insulation, called the dielectric. The dielectric
  is surrounded by a conductive shield, which is
  surrounded by a non-conductive jacket. Coaxial
  cable has better data transmission rate than
  twisted pair.

Coaxial cable Figure 6.5
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Types of Telecommunications Media Fiber-optic
Cable

• Fiber-optic Cable
• Many extremely thin strands of glass or plastic
  bound together in a sheathing which transmits
  signals with light beams. Can be used for voice,
  data, and video.

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Types of Telecommunications Media Microwave
Communications
Microwave Communications Line-of-sight devices
which must be placed in relatively high locations.
Microwave Usage Information is converted to a
microwave signal, sent through the air to a
receiver, and recovered.
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Types of Telecommunications Media Satellite
Transmission
Satellite Transmission Communications satellites
are relay stations that receive signals from one
earth station and rebroadcast them to another.
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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 Comples Topologies

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Network Topologies
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NETWORK TYPES

• Computer Telecommunications Network
• Private Branch Exchange (PBX) Network
• Local Area Network (LAN)
• Backbone Network
• Wide Area Network (WAN)
• Intranet

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Local Area Networks cover limited physical areas
A a network interface card
that contains a network operating system
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Wide Area Networks cover large geographic areas
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LANs

• 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 packages 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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Network Architectures and Protocols

• A protocol is the set of rules for communicating,
  including rules for timing of message exchanges,
  the type of electrical connection used by the
  communications devices, error detection
  techniques, means of gaining access to
  communications channels, and so on
• The goal of network architectures is to promote
  an open, simple, flexible, and efficient
  telecommunications environment. This is
  accomplished by the use of
• Standard protocols
• Standard communications hardware and software
  interfaces
• Standard multilevel interface between end users
  and computer systems
• The OSI Model
• The Internets TCP/IP

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Network Protocols The OSI Architecture
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The Internets TCP/IP
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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 organizaton
  employing TCP/IP Ptotocol
• Organization uses same Web browser, 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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Trends in Telecommunications
Open systems using Internet technologies Digital
network Fiber optic lines and satellite
transmissions
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Telecommunications Strategic Capabilities
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Other E-Business Networks
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CHAPTER 4

• Telecommunications Networking