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Title: Telecommunications and Networks


1
Telecommunications and Networks
  • Chapter 6

2
Telecommunications and Networks
  • telecommunications
  • the components of a telecommunications system.
  • several telecommunications applications.
  • the benefits of a network.
  • basic types of communications media
  • telecommunications hardware and the role
  • network topology five alternatives.

3
Communications
  • Telecommunication
  • The electronic transmission of signals for
    communications, such as telephone, radio and
    television
  • Data communications
  • a subset of telecommunications involving
    computerized data, but not voice communications.

Sender
Receiver
Signal
4
Overview of Telecommunications Systems
5
Telecommunications
6
  • The hardware and software that transmits
    information from one location to another
  • Components
  • Hardware Modems, switches, routers, front-end
    processors, so on.
  • Media Twisted-pair wire, cable, microwave radio,
    so on
  • Networks Internet, intranet, wide area, local
    are, client/server,
  • Software Network operating systems,
    telecommunications software
  • Data communication providers AOL, CompuServe,..
  • Protocols TCP/IP, ..
  • applications

7
Telecommunications Media
8
Basic Communications Channel Characteristics
  • Simplex channel
  • Half-duplex
  • Full-duplex channel
  • Bandwidth
  • The range of frequencies that an electronic
    signal occupies on a given transmission medium.
  • The broader the bandwidth, the more information
    that can be carried
  • Broadband
  • Telecommunications in which a wide band of
    frequencies is available to transmit information,
    allowing more information to be transmitted in a
    given amount of time.

9
Communication Media and Channels
  • Anything that carries an electronic signal and
    interfaces between a sending device and a
    receiving device

10
Types of Media
  • Twisted-Pair
  • Coaxial Cable
  • Fiber-Optic Cable
  • Microwave Transmission

11
(No Transcript)
12
Telecommunications Devices
13
Telecommunication Signals
  • Analog signals
  • Continuous waves
  • Information conveyed by changing wave
    characteristics (amplitude and frequency)
  • Digital signals
  • Discrete pulses
  • Information conveyed in binary form (on or off
    pulses)
  • Easily understood by computer

14
Communication Processors
  • Hardware devices utilized in data transmission
    and reception
  • Modem
  • Multiplexor
  • Front-end processor

15
Modems
  • Analog signals continuous
  • Digital signals discrete
  • Modulation translating digital data to analog
  • Demodulation translating analog data to digital
  • Modems modulate demodulate data

16
  • Multiplexers
  • devices that combine signals from several
    computers to allow them to be sent over a single
    transmission line.
  • Front end processors
  • computers that manage communications to and from
    a computer system. This relieves the main
    computer of work so that it can be free to
    process other tasks. Front end processors are
    usually mainframes or midrange computers.

17
Carriers and Services
18
Telecomm Carriers and Services
  • Telecomm carriers provide telecomm technology
    and services for data communication
  • Common carriers long-distance phone companies
  • Value-added carriers companies that have
    developed private telecommunications systems and
    offer their services for a fee.

19
Telecomm Carriers and Services (continued)
  • Telecomm services
  • Switched lines transmission is routed along
    path to destination
  • Dedicated lines continuous connection is
    established
  • Wide-area Telecomm Service (WATS) lower cost
    long distance telephone service, refers to the
    use of toll-free numbers
  • Integrated Services Digital Network (ISDN) high
    speed data transmission over existing phone lines
  • Digital Subscriber Lines (DSL) - high speed
    digital transmission over existing phone lines
  • Phone dialing services - caller ID, Intelligent
    dialing
  • T1 Carrier

20
Transmission Speeds
21
Networks Distributed Processing
22
  • What is a network?
  • A collection of computers and devices connected
    by communications channels
  • Facilitates communications among users and allows
    users to share resources with other users
  • share data and information
  • share hardware
  • share software

23
Basic Processing Strategies
  • Centralized processing
  • all processing is done at one location.
  • When
  • High level of control required
  • Security is a key issue
  • Remote sites do not have expertise to operate
    system
  • Decentralized processing
  • different locations have their own processing
    devices. Devices at different locations arent
    connected together.
  • When
  • Local independence is required
  • Efficiency, based on local needs, is requirement
  • Remote sites possess individualized skills
    required for local computing tasks
  • Distributed processing
  • computers at different locations are connected by
    a communications network

24
Network Concepts Considerations
  • Network topology
  • Network types
  • Local Area Networks
  • Wide Area Networks
  • International networks
  • Home small business networks

25
  • What is a network topology?
  • The configuration, or physical arrangement, of
    the devices in a communications network
  • Networks usually use combinations of five
    topologies
  • Ring
  • Bus
  • Star
  • Hierarchical
  • Hybrid

26
Fig 6.15
27
Computer Network Type
  • Networks may be classified by size
  • Local Area Networks (LANs)
  • Wide Area Networks (WANs)
  • The Internet
  • Connections to the Internet are through
  • LANS
  • Internet Service Providers (ISP)

28
Local Area Network (LAN)
  • Limited geographical area such as a home, school
    computer laboratory, office building
  • Any topology possible
  • Designs
  • Peer-to-peer
  • Client-server

29
Local Area Networks
30
LAN Components
  • Network cabling physically connects each
    component to the network
  • Hub a device that allows cables to be connected
    together
  • Network interface card allows network cabling
    to be connected to a computer
  • Network Operating System software that controls
    the network
  • Bus a main cable to which all clients and
    servers are connected
  • Ethernet - protocol for transmitting packets over
    a bus

31
  • What is a network operating system?
  • The system software that organizes and
    coordinates the activities on a local area
    network
  • Also called a network OS or NOS
  • Functions
  • AdministrationAdding, deleting, and organizing
    users and performing maintenance tasks
  • File management locating and transferring files
  • Printer management Prioritizing print jobs and
    reports sent to specific printers on the network
  • Security Monitoring and, when necessary,
    restricting access to network resources

32
  • What is a peer-to-peer LAN?
  • A simple, inexpensive network that typically
    connects less than 10 computers together
  • Each computer on a peer-to-peer network can share
    the hardware, data, or information located on any
    other computer in the network
  • Each computer stores files on its own storage
    devices

33
  • What is a client/server LAN?
  • A network in which one or more computers act as a
    server and the other computers on the network can
    request services from the server

34
  • Wide Area Network (WAN)
  • A network that covers a large geographic area
    using a communications channel that combines many
    types of media
  • Can be one large network or can consist of two or
    more LANs connected together
  • The Internet is the worlds largest WAN

35
WAN
Ontario
California
Norway
Wide Area Network
Belgium
Manitoba
Pennsyl- vania
British Columbia
Japan
Dominican Republic
Chile
36
  • What is a metropolitan area network (MAN)?
  • A backbone network that connects local area
    networks in a metropolitan area such as a city or
    town
  • Handles the bulk of communications activity, or
    traffic, across that region

37
Network Types
  • International networks
  • Home and small business networks
  • HomePLC (powerline cable) network
  • Uses the same lines that bring electricity and
    power into your home.
  • Phoneline network
  • Uses existing telephone lines in the home.
  • HomeRF (radio frequency) network
  • Uses radio waves, instead of cables, to transmit
    data.

38
Connecting Computers in a Distributed System
  • Terminal-to-Host
  • In a terminal-to-host configuration, users have
    dumb terminals connected to a host computer. All
    file access and processing is done on the host
  • File Server
  • In a file server environment, the file or
    database resides on a host computer, the file
    server, and applications, including the database
    management system, run on the users computer.
    All processing is done on the users computer.
    When an application needs a record, the file
    server sends the whole file.
  • Client/Server

39
  • Client/server processing
  • Applications can be divided into presentation,
    applications, and data management components
  • Components can be partitioned between the server
    and the clients to form different
    implementations.
  • Peer-to-peer processing
  • Simplified form of client/server
  • Devices attached to network have access to all
    other devices
  • No file server involved
  • Simple set up and maintenance
  • Implemented in many operating systems such as
    Windows 2000 and Windows XP

40
Communications Software and Protocols
41
Network Communication Software
  • Needed to provide a number of network functions
  • Check for errors
  • Format messages
  • Maintain communication logs
  • Ensure data security and privacy
  • Provide message translation

42
Network Communication Software (continued)
  • Components
  • Network Operating System enables all devices on
    network to communicate
  • Network Management Software simplifies human
    network management tasks
  • Protocols specify rules that govern device
    communication over the network and ensure
    communications among computers of different types
    and from different manufacturers

43
Network Communication Software (continued)
  • Types of Protocols
  • Ethernet
  • Transmission Control Protocol/Internet Protocol
    (TCP-IP)
  • SNA

44
Ethernet
  • A LAN network protocol that allows personal
    computers to contend for access to the network
  • Based on a bus topology, but can be wired in a
    star pattern
  • The most popular LAN because it is relatively
    inexpensive and easy to install and maintain
  • original Ethernet standard not very fast by
    todays standards, but works well for small to
    medium networks
  • Fast Ethernet transmits data and information at
    speeds up to 10 times faster than the original
    standard
  • Gigabit Ethernet provides an even higher speed
    of transmission, with speeds up to 10 times
    faster than Fast Ethernet

45
TCP/IP(Transmission Control Protocol/Internet
Protocol)
  • Sends large files accurately over different
    systems
  • The primary communications protocol of the
    Internet
  • A technology that manages the transmission of
    data by breaking it up into packets
  • Packets Data is divided into small pieces called
    packets
  • Routers Devices that direct packets along the
    fastest available path
  • packet switching Technique of breaking a message
    into packets, sending the packets, and then
    reassembling the data

46
Switching and Routing
  • Circuit Switching
  • Physical end-to-end circuit
  • Phone voice service
  • Packet Switching
  • Connectionless
  • Division of data into packets
  • Packets have data and addressing information
  • Packets handled individually by routers
  • Data is reassembled at the destination

47
Packet Switching
To Algae Gush ltgush_at_republicrats.orggt From Gal
Bore ltbore_at_democlicans.orggt Congratulations on
your victory, chump!
125.99.3333
To Algae Gush ltgush_at_republicrats.orggt From Gal
Bore ltbore_at_democlicans.orggt Congratulations on
your victory, chump!
125.99.3333 gushmemo251
125.99.3333 gushmemo252
125.99.3333 gushmemo253
125.99.3333 gushmemo254
48
SNA
  • Systems Network Architecture (SNA)
  • Introduced by IBM in 1974
  • IBM proprietary communications architecture and
    protocols.
  • The structure of SNA is a layered architecture
    much like OSI. But it does not provide full
    scale support of the OSI protocols.

49
Communication Between Protocols
  • Open Systems Interconnection (OSI) model
  • A standard model for network architectures that
    divides data communications functions into seven
    distinct layers to promote the development of
    modular networks that simplify the development,
    operation, and maintenance of complex
    telecommunications networks

50
Open Systems Interconnection (OSI) model
  • Application Layer
  • Presentation Layer (HTTP)
  • Session Layer
  • Transport Layer (TCP)
  • Network Layer (Internet Protocol)
  • Data Link Layer
  • Physical Layer (Packet switching, Router)

51
Internet Protocol andthe Protocol Stack
Network layers
Web Browser
Web Server
Upper Level Application info.
Middle Level Data description
Lower Level Network hardware
Network Card
Network Card
52
Bridge, Routers, and Gateways
53
  • Bridges
  • a bridge connects two local area networks that
    use the same protocol at the second layer of the
    OSI model, the Data Link layer.
  • Routers
  • connect networks that use different data link
    layer protocols. A router looks at the address on
    the message and determines which network to send
    it over.
  • Gateways
  • connect networks that use different protocols in
    the top layers of the OSI stack. Gateways
    reformat messages so that they can be understood
    by dissimilar networks.
  • Switches
  • are now replacing bridges and gateways in many
    places.

54
Typical Topologies
  • Several LANs can be connected via bridges
  • LANs can be connected to external networks via
    gateways

Star
Star
Backbone
Star
Network Access Point
Network Access Point
Ring
Bus
WAN
LANs
55
Telecommunications Applications
56
Telecomm Applications
  • Electronic Mail computer-based messaging
  • Videoconferencing group meetings between
    separate locations
  • Electronic Data Interchange electronic
    transmission of routine business transactions
  • Electronic Funds Transfer electronic processing
    of financial transactions
  • Facsimiles electronic document transmittal
  • Telecommuting working at home via telecomm
    links
  • Distance Learning classes offered on same
    time/different place, or different time/
    different place basis

57
Electronic Data Interchange, (EDI)
  • The computer-to-computer exchange of data between
    companies or trading partners
  • For example,
  • Using EDI, the a purchase order would be created
    on the computer and sent directly to the
    suppliers computer, which would receive it and
    initiate the processing. All of the suppliers
    computer systems would use the same database of
    information. The invoicing system, for example,
    would be notified (by the computer application)
    when the paint is shipped, and an invoice would
    automatically be electronically transmitted to
    ABCs computer. ABCs computer would schedule the
    invoice for payment (which would also be done
    electronically using electronic funds transfer
    between banks).

58
Chapter Summary
  • Components of a telecomm system
  • Types of communication media used in telecomm
    systems
  • Types of networks
  • Ways to organize network processing
  • Ways to utilize networks in businesses today
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