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    UNIT 2-Introduction To Computer Networks

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    levisqueen26
    Second part of networking

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    UNIT 2-Introduction To Computer Networks

    Uploaded by

    levisqueen26
    7 views12 pages
    Second part of networking

    Original Title

    UNIT 2-Introduction to Computer Networks

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    © © All Rights Reserved

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    PDF, TXT or read online from Scribd

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    Second part of networking

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    7 views12 pages

    UNIT 2-Introduction To Computer Networks

    Uploaded by

    levisqueen26
    Second part of networking

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 12

    IT 121: INTRODUCTION TO COMPUTER NETWORKS

    UNIT TWO: NETWORK ARCHITECTURE


    • Network Architecture: Is the way network devices and
    services are structured to serve the connectivity needs
    of client devices.

    • Network devices typically include switches and routers.


    • Network line configuration: is a method by which two
    or more devices are attached to a link and is also known
    as connection.
    • A network is two or more devices connected through a
    link. A link is a communication pathway that transfers

    INSTRUCTOR: PEng: VIDATE CYRIL MSOKA


    IT 121: UAUT
    data from one device to another. Devices can be a
    computer, printer, or any other device that is capable to
    send and receive data. For visualization purposes,
    imagine any link as a line drawn between two points.

    • For communication to occur, two devices must be


    connected in some way to the same link at the same
    time.

    There are two possible types of connections:


    (i) Point-to-Point Connection
    (ii) Multipoint Connection

    (i) Point-to-Point Connection :


    • A point-to-point connection provides a dedicated link
    between two devices.
    • The entire capacity of the link is reserved for
    transmission between those two devices.
    • Most point-to-point connections use an actual length of
    wire or cable to connect the two ends, but other options
    such as microwave or satellite links are also possible.

    INSTRUCTOR: PEng: VIDATE CYRIL MSOKA


    IT 121: UAUT
    • Point to point network topology is considered to be one
    of the easiest and most conventional networks
    topologies.
    • It is also the simplest to establish and understand.
    • Example: Point-to-Point connection between the
    remote control and Television for changing the
    channels.

    Multipoint Connection:
    1. It is also called Multidrop configuration. In this
    connection, two or more devices share a single link.
    2. If more than two devices share the link then the channel
    is considered as a ‘shared channel’. With shared
    capacity, there can be two possibilities in a Multipoint
    INSTRUCTOR: PEng: VIDATE CYRIL MSOKA
    IT 121: UAUT
    • Line configuration:
    Spatial Sharing: If several devices can share the link
    simultaneously, it’s called spatially shared line
    configuration.
    Temporal (Time) Sharing: If users must take turns using
    the link, then it’s called temporally shared or Time Shared
    Line configuration.

    NETWORKING AND INTERNETWORKING DEVICES


    Below are types of network devices:
    • Repeater:
    Is an electronic device that amplifies the signal it receives.
    You can think of repeater as a device which receives a
    signal and retransmits it at a higher level or higher power
    so that the signal can cover longer distances, more than
    100 meters for standard LAN cables. Repeaters work on
    the Physical layer.

    INSTRUCTOR: PEng: VIDATE CYRIL MSOKA


    IT 121: UAUT
    • Bridges
    A bridge in a computer network is a device used to
    connect multiple LANs together with a larger Local Area
    Network (LAN).
    The mechanism of network aggregation is known as
    bridging.
    The bridge is a physical or hardware device but operates
    at the OSI model’s data link layer and is also known as a
    layer of two switches.

    Many organizations have multiple LANs and wish to


    connect them.
    This is done when the connections are made with devices
    called bridges.
    Bridges operate in the data link layer,

    INSTRUCTOR: PEng: VIDATE CYRIL MSOKA


    IT 121: UAUT
    Will look at how bridges work and are used to join multiple
    physical LANs into a single logical LAN.
    - Uses of Bridges
    We will mention three reasons why a single organization
    may end up with multiple LANs.
    - First, many university and corporate departments
    have their own LANs to connect their own personal
    computers, servers, and devices such as printers.
    Since the goals of the various departments differ,
    different departments may set up different LANs,
    without regard to what other departments are doing.
    Sooner or later, though, there is a need for
    interaction, so bridges are needed
    - Second, the organization may be geographically
    spread over several buildings separated by
    considerable distances. It may be cheaper to have
    separate LANs in each building and connect them
    with bridges and a few long-distance fiber optic links
    than to run all the cables to a single central switch
    - Third, it may be necessary to split what is logically a
    single LAN into separate LANs (connected by bridges)
    to accommodate the load.

    INSTRUCTOR: PEng: VIDATE CYRIL MSOKA


    IT 121: UAUT
    - The topology of two LANs bridged together is shown
    in Figure below:

    (a) Bridge connecting two multidrop LANs.


    (b) Bridges (and a hub) connecting seven point-to-
    point stations.
    Note that bridges are used to improve network
    performance.

    Types of Bridges:

    There are three types of bridges in computer networks,


    which are as follows:
    1. Transparent bridge
    2. Source routing bridge
    3. Translational bridge

    INSTRUCTOR: PEng: VIDATE CYRIL MSOKA


    IT 121: UAUT
    Transparent Bridge:

    Transparent bridges are invisible to other devices on the


    network.
    This bridge doesn’t reconfigure the network on the
    addition or deletion of any station.
    The prime function of the transparent bridge is to block or
    forward the data according to the MAC address.

    Source Routing Bridge:

    Source routing bridges were developed and designed by


    IBM specifically for token ring networks.
    The frame’s entire route is embedded with the data
    frames by the source station to perform the routing
    operation
    So that once the frame is forwarded it must follow a
    specific defined path/route.

    Translational Bridge:

    Translational bridges convert the received data from one


    networking system to another. Or it is used to
    communicate or transmit data between two different
    types of networking systems. Like if we are sending data
    from a token ring to an Ethernet cable, the translational
    INSTRUCTOR: PEng: VIDATE CYRIL MSOKA
    IT 121: UAUT
    cable will be used to connect both the networking system
    and transmit data.
    Advantages:

    • Bridges can be used as a network extension like they can


    connect two network topologies together.
    • It has a separate collision domain, which results in

    increased bandwidth.
    • It can create a buffer when different MAC protocols are

    there for different segments.


    • Highly reliable and maintainable. The network can be

    divided into multiple LAN segments.


    • Simple installation, no requirement of any extra

    hardware or software except the bridge itself.


    • Protocol transparency is higher as compared to other

    protocols.
    Disadvantages:
    • Expensive as compared to hubs and repeaters.

    • Slow in speed.

    • Poor performance as additional processing is required

    to view the MAC address of the device on the network.


    • As the traffic received is in bulk or is broadcasted traffic,

    individual filtering of data is not possible.


    • During the broadcasting of data, the network has high

    broadcast traffic and broadcast storms can be formed.


    •

    INSTRUCTOR: PEng: VIDATE CYRIL MSOKA


    IT 121: UAUT
    Uses of Bridge in Computer Network:
    • Bridges are used to increase the network capacity as

    they can integrate multiple LANs together.


    • On receiving a data frame, databases use the bridge to

    decide whether to accept or reject the data.


    • In the OSI model, it can be used to transmit the data to

    multiple nodes of the network.


    • Used to broadcast the data even if the MAC address or

    destination address is unavailable.


    • It forwards data packets despite faulty nodes.

    • The data packet can be forwarded or discarded by the

    bridge when the MAC address is available.


    Functions of Bridges in the Network
    • The bridge is used to divide LANs into multiple

    segments.
    • To control the traffic in the network.

    • It can interconnect two LANs with a similar protocols.

    • It can filter the data based on destination/MAC

    address.

    Switches
    The primary responsibility of a switch is to examine the
    incoming traffic and determine whether to filter or
    forward it.

    INSTRUCTOR: PEng: VIDATE CYRIL MSOKA


    IT 121: UAUT
    Gateway

    • A gateway is a network node used in


    telecommunications that connects two networks with
    different transmission protocols together. Gateways
    serve as an entry and exit point for a network as all data
    must pass through or communicate with the gateway
    prior to being routed.
    Connection Oriented Service:
    Connection-oriented service entails the establishment and
    termination of a connection for the transmission of data between
    two or more devices.
    Connectionless service does not need the establishment of any
    connection or termination procedure in order to transport data
    across a network.
    Difference between Connection-oriented and Connection-less Services:
    S.NO Connection-oriented Service Connection-less Service

    Connection-oriented service is related to Connection-less service is related to


    1. the telephone system. the postal system.

    Connection-oriented service is preferred Connection-less Service is preferred


    2. by long and steady communication. by bursty communication.

    Connection-less Service is not


    3. Connection-oriented Service is necessary. compulsory.

    Connection-less Service is not


    4. Connection-oriented Service is feasible. feasible.

    INSTRUCTOR: PEng: VIDATE CYRIL MSOKA


    IT 121: UAUT
    In connection-oriented Service, In connection-less Service,
    5. Congestion is not possible. Congestion is possible.

    Connection-oriented Service gives Connection-less Service does not


    6. the guarantee of reliability. give a guarantee of reliability.

    In connection-oriented Service, In connection-less Service, Packets


    7. Packets follow the same route. do not follow the same

    A managed switch enables better control of networks and the


    data frames moving through them. Unmanaged switches, on the
    other hand, enable connected devices to communicate with one
    another in their most basic form.

    INSTRUCTOR: PEng: VIDATE CYRIL MSOKA


    IT 121: UAUT

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