Beyda, W. J., DATA COMMUNICATIONS FROM BASICS TO BROADBAND, 2000 - PowerPoint PPT Presentation

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Beyda, W. J., DATA COMMUNICATIONS FROM BASICS TO BROADBAND, 2000

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A (manufacturer's) strategy for connecting (its) host ... OpenVMS. Novell. Proprietary. Architectures and Protocols. Year 2001.... 40% Will be Windows NT ... – PowerPoint PPT presentation

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Title: Beyda, W. J., DATA COMMUNICATIONS FROM BASICS TO BROADBAND, 2000


1
Beyda, W. J., DATA COMMUNICATIONS FROM BASICS TO
BROADBAND, 2000
  • Electronically reproduced by permission of
    Prentice Hall, Upper Saddle River, New Jersey.

2
Architectures and Protocols
  • What is a communication architecture?

3
Architectures and Protocols
  • A (manufacturers) strategy for connecting (its)
    host computers, terminals, and communication
    equipment.
  • Specifically, it can describe special functions
    that the host computers hardware and software
    must perform to allow application programs to
    communicate amongst themselves and the outside
    world.

4
Architectures and Protocols
  • Thus far in this course and in the book, we have
    only considered computer-to-terminal
    communications. We will now consider
    computer-to-computer communications..

5
Architectures and Protocols
  • Why do we want computers to be able to
    communicate with other computers?

6
Architectures and Protocols
  • So that like computers can share data.
  • So that like computers can share resources.
  • So that unlike computers can share data.
  • So that unlike computers can share resources.

7
Architectures and Protocols
  • How many operating systems are there in use today?

8
Architectures and Protocols
  • Some common ones
  • Windows NT
  • Unix (HP-UX, SunOS, AIX,BSDI,SCO)
  • LiNUX
  • Windows 95
  • Windows 98
  • OpenVMS
  • Novell
  • Proprietary

9
Architectures and Protocols
  • Year 2001.
  • 40 Will be Windows NT
  • 40 Will be Unix
  • 20 Will be others
  • 95 of all businesses will be mixed environment!
  • Source 1999 Oracle presentation, Jacksonville,
    Florida.

10
Architectures and Protocols
  • In the past, if you wanted unlike systems to
    communicate, you would have to purchase something
    (hardware/software/both) to perform the
    conversions.
  • Why not have common communications to solve this
    problem?

11
Architectures and Protocols
  • Enter International Standards Organization (ISO)
    and the Open Systems Interconnect Model (OSI
    model).
  • (Dont get ISO and OSI confused!)

12
Architectures and Protocols
  • What is the OSI Model?

13
Architectures and Protocols
  • It is a universal architecture for computer
    communications.
  • It is non-proprietary.
  • It breaks down the task of communications into
    seven independent layers, each with its own tasks
    and responsibilities.

14
Architectures and Protocols
  • In 1985 the Corporation for Open Systems, COS
    formed.
  • It was non-profit.
  • It consisted of representatives of major host
    computer manufacturers at the time, including
    Control Data, DEC, HP, Honeywell, IBM, NCR,
    Tandem, Unisys, Wang, Xerox, and others.

15
Architectures and Protocols
  • Seven Layers of the ISO model defined
  • Layer 7 (Higher Layer) Away Layer
  • Layer 6 (Higher Layer) Pizza Layer
  • Layer 5 (Higher Layer) Sausage Layer
  • Layer 4 (Higher Layer) Throw Layer
  • Layer 3 (Lower Layer) Not Layer
  • Layer 2 (Lower Layer) Do Layer
  • Layer 1 (Lower Layer) Please Layer

16
Architectures and Protocols
  • Seven Layers of the ISO model defined
  • Layer 7 (Higher Layer) Application Layer
  • Layer 6 (Higher Layer) Presentation Layer
  • Layer 5 (Higher Layer) Session Layer
  • Layer 4 (Higher Layer) Transport Layer
  • Layer 3 (Lower Layer) Network Layer
  • Layer 2 (Lower Layer) Data Link Layer
  • Layer 1 (Lower Layer) Physical Layer

17
Architectures and Protocols
  • Away -gt Application Layer
  • Pizza -gt Presentation Layer
  • Sausage -gt Session Layer
  • Throw -gt Transport Layer
  • Not -gt Network Layer
  • Do -gt Data Link Layer
  • Please -gt Physical Layer

18
Architectures and Protocols
  • More on the OSI model...
  • Each layer represents a particular function.
  • Sometimes, each function is performed by a
    separate piece of hardware or software.
  • Sometimes a single program can perform the
    functions of several layers.

19
Architectures and Protocols
20
Architectures and Protocols
  • Layer 1 Physical Layer
  • responsible for transmission of bits.
  • Implemented in hardware and software drivers
    encompasses the mechanical, electrical, and
    functional interface.
  • Examples RS-232-C (Sync and Async), ethernet,
    X.25, twisted-pair, coaxial cable, fiber optic
    cable, satellites, microwave towers, and radio
    waves.

21
Architectures and Protocols
  • Layer 2 Data Link Layer
  • responsible for ensuring error-free, reliable
    transmission of data.
  • establishes the communication link between
    devices over the physical channel.
  • Responsible for framing, error control, time-out
    levels, and data formatting can request
    retransmissions at this level.
  • Maintains sequence control for frames on the
    communication link.
  • OSI uses the High-level data link control (HDLC)
    protocol for these services. IBM uses Binary
    Synchronous Protocol (BSC) and Synchronous Data
    Link Control (SDLC). DEC uses DDCMP.

22
Architectures and Protocols
  • Layer 3 Network Layer
  • responsible for routing messages throughout a
    network.
  • Internodal traffic control.
  • OSI utilizes Internetwork Protocol (IP) at this
    level.

23
Architectures and Protocols
  • Layers 1-3 (Physical, Data Link, and Network) are
    referred to as the lower levels
  • Layers 4-7 (Transport, Session, Presentation,
    Application) are referred to as the higher or
    upper levels.

24
Architectures and Protocols
  • Layer 4 Transport Layer
  • Responsible for isolating the functions of the
    higher and lower levels. This level will accept
    messages from the higher levels and break them
    down for the lower layers.
  • Two popular protocols have been developed to
    provide transport services Transmission Control
    Protocol (TCP), which as of 1997 was not an
    official OSI protocol, and the OSI Transport
    Protocol (TP).

25
Architectures and Protocols
  • Layer 5 Session Control
  • Formats the data for transfer between end nodes
    of the network.
  • Security (login/passwords) is handled at this
    level.
  • Provides session-to-session restart and recovery,
    and is responsible for maintaining the end-to-end
    connection until a termination request is
    received from either system.

26
Architectures and Protocols
  • Layer 6 Presentation
  • takes data and translates it into a format that
    will enable it to be processed by the receiving
    system(terminal, printer, host computer).
  • Functions include data formatting, code set
    conversions (e.g. ASCII to EBCDIC), text
    compression for higher throughput efficiency, and
    encryption services.

27
Architectures and Protocols
  • Layer 7 Application
  • Provides access to the network for the end user.
  • Some application software may permit remote
    terminals to access a host computer some may
    allow file transfers.
  • Network management, resource sharing, and
    database management services also reside within
    this layer.

28
Architectures and Protocols
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