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    3-Network Models M

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    3-Network Models M

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    3-Network Models m

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    5 views6 pages

    3-Network Models M

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    of 6

    Network Basics

    1
    Network Models

    Network Models
    Levels like application and device controls took place over the
    communication network. Those are usually bounded by structural model and
    framework wherein each part of it has its own work to do for completing the
    resource sharing or exchange. The ISO has created a standard way or models
    of how the things should communicate within the network.
    Upon completion of this module, the students should be able to:
    1. Differentiate Protocol Model and a Reference Model
    2. Define the TCP/IP Model and The OSI Model
    3. Discuss the function of the Layers of the OSI Model and TCP/IP Model
    4. Compare the OSI Model with the TCP/IP Model

    Protocol and Reference Models


    Protocol Model
    Protocol model provides a model that is closely equivalent to the structure
    of a certain protocol.
    Reference Model
    Reference model provides a common reference for maintaining consistency
    within all types of network protocols and services. It is not intended to be an
    implementation specification

    Network Models
    Network Models Defined
    A Network Model is a set of network layers and how they interact. The
    following are the two most important and well-known network models:
    1. OSI Model
    OSI stands for Open Systems Interconnect.
    a. This is a system that breaks down network function.
    b. This is the most popular type of internetwork reference model.
    c. Consist of seven layers.

    2. TCP/IP Model
    TCP/IP stands for Transmission Control Protocol/Internet Protocol.
    a. Also known as the DOD (Department of Defense) Model.
    b. This is the protocol that is used in the internet.

    Course Module
    The OSI Model
    As mentioned above, the OSI model is a network model widely used today.
    This section discusses OSI in detail.
    Layers of the OSI Model
    The OSI Model has the following layers:
    1. Application Layer
    2. Presentation Layer
    3. Session Layer
    4. Transport Layer
    5. Network Layer
    6. Data-link Layer
    7. Physical Layer
    Below is a diagram showing the OSI Model and its equivalent layer:

    Figure 1: The OSI Model


    Source: http://www.omnisecu.com/tcpip/osi-model.php
    Function of the OSI Model Layers
    The following are the functions of each layer in the OSI Model.
    1. Application Layer (Layer 7)
    Application layer is the topmost layer of the OSI Model. This layer
    provides a means for the user to interact with the software application.
    Everything at this layer is application-specific. This layer provides
    application services such as: file transfers, e-mail, and other network
    software services.

    2. Presentation Layer (Layer 6)


    This layer provides proper common data format that is sent across
    ApplicationLayer services.

    3. Session Layer(Layer 5)
    Network Basics
    3
    Network Models

    This layer establishes, manages and terminates connections between


    applications. This layer provides services to the presentation layer.

    4. Transport Layer (Layer 4)


    This layer defines services to segment, transfer, and reassemble data
    individual communications between the end-devices. This layer basically
    describes how data is sent across the network.

    5. Network Layer (Layer 3)


    This layer provides services to exchange the individual pieces of data
    over the network between identified network devices.

    6. Data Link Layer (Layer 2)


    This layer provides methods for exchanging data over a common media.

    7. Physical Layer (Layer 1)


    This layer describes the mechanical, electrical, functional, and procedural
    means to activate, maintain, and deactivate physical connections for bit
    transmission and to and from a network device.

    ISO and the OSI Layer


    The International Organization for Standardization (ISO) released the OSI
    reference model in 1984 and it was the descriptive scheme they ever created.
    According to www.iso.ch:
    “ISO. A network of national standards institutes from 140 countries working in
    partnership with international organizations, governments, industry, business
    and consumer representatives. A bridge between public and private sectors.”

    Figure 2: ISO Online Website


    Source: https://www.iso.ch/iso/en/ISOOnline.openerpage

    Course Module
    The TCP/IP Model
    This section discusses TCP/IP in detail.
    Layers of the TCP/IP Model
    1. Application
    2. Transport
    3. Internet
    4. Network Access

    Figure 3: The TCP/IP Model


    Source: http://4.bp.blogspot.com/_KjNkTh3VA1Y/S-
    a6pRCSk9I/AAAAAAAAAS4/0njdhJERAw4/s1600/tcp-ip-model.jpg
    Function of the TCP/IP Layers
    The following are the functions of each layer in the TCP/IP Model.
    1. Application Layer (Layer 4)
    This layer represents data to the user plus encoding and dialog
    control

    2. Transport Layer (Layer 3)


    Supports communication between diverse devices across diverse
    networks

    3. Internet Layer (Layer 2)


    Determines the best part through the network

    4. Network Access Layer (Layer 1)


    Controls the hardware devices and media that make up the network

    Protocol Data Unit (PDU)


    The form that a piece of data takes at any layer at each stage of the process, a
    PDU has a different name to reflect its new appearance. PDUs are named
    according to the protocols of the TCP/IP suite. These are the following such
    as:
    a. Data
    The general term for the PDU used at the Application layer
    b. Segment
    Transport Layer PDU
    Network Basics
    5
    Network Models

    c. Packet
    Internetwork Layer PDU
    d. Frame
    Network Access Layer PDU
    e. Bits
    A PDU used when physically transmitting data over the medium

    OSI Model vs TCP/IP Model


    OSI Model and TCP/IP Model Comparison
    a. OSI lost out to TCP/IP as the protocol suite of the Internet.
    b. The TCIP/IP Model is mapped to the OSI Model.
    c. TCP/IP is the protocol used today but OSI Model is often used to
    describe network communication.

    Figure 4: The TCP/IP Model and OSI Model Comparison


    Source: http://www.omnisecu.com/images/tcpip/comparison-tcpip-osi.jpg
    As you can see from the diagram above:
    a. The Application layer of the TCP/IP Model is consisting of the Application,
    Presentation, and Session Layers of the OSI Model;
    b. Both Layers have their equivalent Transport Layer;
    c. The Network Layer in the TCP/IP Model is equivalent to the Network
    Layer of the OSI Model; and
    d. The Network Access Layer of the TCP/IP Model is equivalent to the Data
    Link and Physical Layers of the OSI Model.

    Glossary
    International Organization for Standardization (ISO): This is a network of
    national standards institutes from 140 countries working in partnership with
    international organizations, governments, industry, business and consumer
    representatives. A bridge between public and private sectors.
    Course Module
    Protocol model: This provides a model that is closely equivalent to the
    structure of a certain protocol.
    Network Model: This is a set of network layers and how they interact.
    OSI (Open Systems Interconnect): This is a system that breaks down
    network function. This is the most popular type of internetwork reference
    model.
    Protocol Data Unit (PDU): The form that a piece of data takes at any layer at
    each stage of the process, a PDU has a different name to reflect its new
    appearance.
    Reference model: This provides a common reference for maintaining
    consistency within all types of network protocols and services. It is not
    intended to be an implementation specification
    TCP/IP (Transmission Control Protocol/Internet Protocol): Also known
    as the DOD (Department of Defense) Model. This is the protocol that is used
    in the internet.

    References
    Books and Journals
    Cisco Networking Academy; 2016; Introduction to Networks v6 Companion
    Guide1st Edition; United States of America: Amazon Digital Services LLC.
    Tetz, Edward;2016; Cisco Networking All-in-One For Dummies1st
    Edition;United States of America: For Dummies
    Troy, McMillan; 2016; Cisco Networking Essentials 2nd Edition; United
    States of America:Sybex
    Online Supplementary Reading Material
    An OSI layer model for the 21st century;
    http://davidad.github.io/blog/2014/04/24/an-osi-layer-model-for-the-
    21st-century/; September 4, 2017
    The OSI Model: Understanding the Seven Layers of Computer Network;
    http://ru6.cti.gr/bouras-old/WP_Simoneau_OSIModel.pdf ; September 4,
    2017
    Online Instructional Videos
    Networking Basic: Network Model;
    https://www.youtube.com/watch?v=upkhFoM3AEA; September 4, 2017
    Network Layers - OSI, TCP/IP Models -Part 1;
    https://www.youtube.com/watch?v=SII38b0RJr8; September 4, 2017
    Network Layers - OSI, TCP/IP Models -Part 2;
    https://www.youtube.com/watch?v=W74H0FVXY_w; September 4, 2017

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