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Title: Telecommunications, the Internet, Intranets, and Extranets


1
Telecommunications, the Internet, Intranets, and
Extranets
  • Chapter 4

2
Learning Objectives
  • Define the term telecommunications and identify
    and describe the function of the components of a
    telecommunications system.
  • Identify and briefly describe three basic data
    processing strategies, including their advantages
    and disadvantages.

3
Learning Objectives
  • Briefly describe how the Internet works,
    including alternatives for connecting to it and
    the role of Internet service providers.
  • Identify and briefly describe common Internet
    services.

4
Learning Objectives
  • Describe the World Wide Web and the way it works,
    including the use of Web browsers, search
    engines, Java, and other Web tools.
  • Define the terms intranet and extranet and
    discuss how organizations are using them.
  • Identify several control and management issues
    associated with the use of networks.

5
Telecommunication
  • Electronic transmission of signals for
    communications
  • Telecommunications device is a hardware component
    that allows electronic communication to occur
  • Telecommunications medium carries an electronic
    signal and interfaces between a sending device
    and a receiving device

6
Elements of a Telecommunications System
7
Media Types (1)
  • Twisted-pair wire cable Twisted pairs of copper
    wire
  • Used in telephone service
  • Slow transmission
  • Coaxial cable Conductor wire is insulated
  • Faster than twisted-pair
  • Fiber-optic cable Thin strands of glass bound
    together
  • Uses light beams
  • Faster than coaxial cable

8
Media Types (2)
  • Microwave transmission High-frequency radio
    signal
  • Must have unobstructed line of sight between
    sender and receiver
  • Possible to intervene
  • Cellular transmission Divide area into cells
  • Each cell has a mobile telephone subscriber unit
  • Possible to intervene
  • Infrared transmission Signals as light waves

9
Common Wiring and Cabling Types
10
Common Telecommunications Devices
  • Modem Translates data from digital form into
    analog form (for ordinary phones) and back
  • MOdulation and DEModulation
  • Fax modem Facsimile device but also a modem
  • Multiplexer Allow several signals to be
    transmitted over the same line
  • PBX Manages both voice and data transfer
  • Switching equipment routes phone calls and
    messages within the building

11
Carriers and Services
  • Common carriers Turk Telecom, ATT
  • Switched lines
  • Use switching equipment to connect one phone to
    another
  • Switch Special purpose circuit that directs
    messages in certain directions
  • Digital subscriber lines (DSL)
  • Use existing lines to transmit signals over
    500Kbps
  • Faster Internet access

12
Costs, Advantages, and Disadvantages of Several
Line and Service Types
Line/Service Speed Cost per month Advantages Disadvantages
Standard phone line 56Kbps 10-40 Broadly available Too slow
ISDN 64-128Kbps 50-150 Faster Not available everywhere
DSL 500Kbps-1.5Mbps 20-120 Use standard line Expensive not available ew.
Cable modem 500Kbps-1.5Mbps 20-120 Use existing cable
T1 1.544 Mbps 600-1200 FAST used by corporations EXPENSIVE
Satellite 60-800Kps 30-120 Instead of cable or DSL Expensive installation
13
Networks and Distributed Processing
  • Computer network - communications media, devices,
    and software needed to connect two or more
    computer systems.
  • Centralized processing - processing occurs in a
    single location or facility.
  • Decentralized processing - processing devices are
    placed at various locations.
  • Distributed processing - computers are placed at
    remote locations but are connected to each other
    via telecommunications devices.

14
Terminal-to-Host Connection
  • Host computer has the data and the processing
    power
  • Dumb terminal contacts host computer for jobs

15
File Server Connection
  • The application and database reside in host
    computer.
  • Files transferred as a whole and processed by the
    user

16
Client/Server Connection
  • Servers have special functionalities (database
    server, program execution, etc.)
  • Clients request services from servers
  • Clients process service results

17
Network Types
  • Local area network (LAN)
  • Same geographic area
  • Wired into office buildings (unshielded
    twisted-pair)
  • Wide area network (WAN)
  • Microwave and satellite transmission
  • Long-distance calls
  • International network
  • Transborder data flow
  • International laws

18
A Typical LAN
19
A Wide Area Network
20
Connecting Computing Devices Using a Home Network
21
Communications Software and Protocols
  • Communications software - provides a number of
    important functions in a network
  • Network operating system - controls the computer
    systems and devices on a network and allows them
    to communicate with each other
  • Network management software - a manager can
    monitor the use of individual computers and
    shared hardware
  • Communications protocol - rules and standards
    that make communications possible

22
Common Communications Protocols
Protocol Description
Open Systems Interconnection (OSI) Divides data communication into seven layers for maintenance
Transport control protocol/Internet Protocol (TCP/IP) Primary communication protocol of the Internet
Ethernet Used in LANs
Asynchronous transfer mode (ATM) Organizes data into 53-byte cells for fast transmission
802.11a Supports wireless ATM devices
Bluetooth Wireless communication for cell phones, handheld computers
802.11b (Wi-fi) Wireless communication for cell phones, handheld computers
23
Use and Functioning of the Internet
24
Routing Messages Over the Internet
25
How the Internet Works
  • Internet Protocol (IP) Set of rules to pass
    packets from one computer to another
  • Transport Control Protocol (TCP) Set of rules to
    establish and break connections
  • Internet Protocol Address Unique address for
    each computer on the Internet
  • Static vs. dynamic

26
U.S. Top-Level Domain Affiliations
27
Three Ways to Access the Internet
28
Internet Service Providers
  • Organizations that provide access to the Internet
  • Choose based on price, reliability, other
    features (e-mail address)
  • Examples Superonline, E-kolay

29
Internet and Telecommunications Services
30
Summary of Internet Services (1)
  • E-mail
  • Instant messaging
  • Telnet/SSH
  • FTP
  • Chat rooms
  • Internet phone
  • Internet video conferencing

31
Summary of Internet Services (2)
  • Shop on the Web
  • Auctions http//www.gittigidiyor.com/
  • Distance learning
  • Music, radio on the Internet

32
Common Abbreviations Used in Personal E-Mail
33
Two Approaches to Electronic Data Interchange
34
Public Network and Specialized Services
35
The World Wide Web
36
The World Wide Web
  • An Internet service comprising tens of thousands
    of independently owned computers that work
    together as one.
  • Home page Cover page with text and graphics
  • Hypertext markup language (HTML) Standard
    language to describe Web pages

37
Several Interesting Web Sites
38
Sample HTML
39
Search Engine
40
Intranets and Extranets
41
Intranets and Extranets
  • Intranet an internal corporate network built
    using Internet and WWW standards and products
  • Extranet - a network that links selected
    resources of the intranet of a company with its
    customers, suppliers, or other business partners
  • Virtual private network - a secure connection
    between two points across the Internet
  • Firewall - a device that sits between your
    internal network and the outside Internet

42
Summary of Internet, Intranet, and Extranet Users
43
Virtual Private Network
44
Net Issues
45
Privacy and Security
  • Cookie Text that is put on user computer to
    track Web site usage
  • Cryptography Converting a message into a secret
    code and then back into the message
  • Encryption
  • Digital Signature Who sent the message, did the
    message change on the way?

46
Cryptography
47
Summary
  • Networks - used to share hardware, programs, and
    databases across the organization.
  • Internet - transmits data from one computer
    (called a host) to another.
  • The Web - a collection of tens of thousands of
    independently owned computers that work together
    as one in an Internet service.
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