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Chapter 3 Physical Components of a Network


Chapter 3 Physical Components of a Network 3.1 Configuring a Network Interface Card 3.2 Topologies 3.3 Media Types 3.4 Network Devices – PowerPoint PPT presentation

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Title: Chapter 3 Physical Components of a Network

Chapter 3Physical Components of a Network
  • 3.1 Configuring a Network Interface Card
  • 3.2 Topologies
  • 3.3 Media Types
  • 3.4 Network Devices

Configuring a Network Interface Card
What is a NIC?
  • A network interface card (NIC) is a device that
    plugs into a motherboard and provides ports for
    the network media connections.
  • It is the component that interfaces with the
    local-area network (LAN).
  • The following things are important to consider
    when selecting a NIC
  • The type of network
  • The type of media
  • The type of system bus

Setting the IP Address
  • In Windows, the IP address is manually entered
    into the TCP/IP properties dialog box.
  • The configuration box is used to set the address
    settings, or configurations that are entered into
    the host machine TCP/IP dialog box, which
  • An IP address
  • A subnet mask
  • Default gateway address
  • Domain Name System (DNS)
  • Windows Internet Naming Service (WINS)

DHCP Servers
  • DHCP is a software utility that automatically
    assigns IP addresses to PCs.
  • The computer running the software is known as a
    DHCP server.
  • DHCP servers assign the IP addresses and TCP/IP
    configuration information to computers configured
    as DHCP clients.
  • This dynamic process eliminates the need for
    manual IP address assignments.

Domain Name System
  • The Domain Name System (DNS) is used to translate
    the computer names such as to the
    corresponding unique IP address.
  • Address translations are used each time the
    Internet is accessed.
  • The process of translating names to addresses is
    known as name resolution.

Domain Name System
  • The DNS server keeps records that map computer
    (host) names and their corresponding IP address.
  • These record types are combined in the DNS table.
  • When a host name needs to be translated to its IP
    address, the client contacts the DNS server.
  • A hierarchy of DNS servers exists on the
    Internet with different servers maintaining DNS
    information for their own areas of authority,
    called zones.

Default Gateway
  • A computer located on one network segment that is
    trying to talk to another computer on a different
    segment sends the data through a default gateway.
  • The default gateway is the near-side interface of
    the router.
  • It is the interface on the router to which the
    local computer network segment or wire is

The Network Topology
  • The network topology defines the layout of the
  • It shows how devices on the network are
  • Devices on the network are termed nodes.
  • A network has both a physical and a logical

Physical versus Logical Topology
  • Physical topology shows the physical topology of
    a network, which refers to the actual physical
    layout of the devices and media.

Physical versus Logical Topology
  • Logical topology refers to the paths that signals
    travel from one point on the network to another.
  • These two terminologies can be confusing, because
    the word "logical" in this instance has nothing
    to do with the way the network appears to be

Identifying Network Topologies
  • Bus Topology
  • Commonly referred to as a linear bus, all the
    devices on a bus topology are connected by one
    single cable, which proceeds from one computer to
    the next.
  • This topology is rarely used and would only be
    suitable for a home office or small business with
    only a few hosts.

Identifying Network Topologies
  • Advantages of a bus topology
  • The thinnet cabling it uses is quite inexpensive.
  • It uses less cable compared to other physical
    topologies like star or extended star
  • It works well for small networks
  • It does not need a central device, such as a hub,
    switch, or router
  • Disadvantages of a bus topology
  • It results in slower access to the network and
    less bandwidth due to the sharing of the same
    cable by all devices
  • It is challenging to identify and isolate
  • A break at any point in the bus cable can disable
    the entire bus network
  • It needs terminators

Identifying Network Topologies
  • Star Topology
  • The star topology is the most commonly used
    architecture in Ethernet LANs and resembles
    spokes in a bicycle wheel.
  • A star topology generally costs more to implement
    than the bus topology because more cable is used
    and a central device is needed, such as a hub,
    switch, or router.

Identifying Network Topologies
  • Advantages of a Star Topology
  • It is upgradeable, flexible, and reliable
  • It is easy to design and install
  • This topology makes diagnosing problems
    relatively easy since the problem is localized to
    one computer or device
  • This topology allows for more throughput than any
    other topology
  • Disadvantages of a Star Topology
  • It requires a lot of cable to connect computers
    since a cable is required between each device and
    the central location.
  • It is more expensive to build because of the
    additional cost of cables and devices like hubs
    and switches that are needed to run between the
    central device and each computer

Identifying Network Topologies
  • Ring Topology
  • A frame, called a token, travels around the ring
    and stops at each node.
  • If a node wants to transmit data, it adds that
    data and the addressing information to the frame.
  • The frame continues around the ring until it
    finds the destination node, which takes the data
    out of the frame.
  • The advantage of using this method is that there
    are no collisions of data packets.

Identifying Network Topologies
  • Ring Topology
  • With single ring all the devices on the network
    share a single cable, and the data travels in one
    direction only.
  • With dual ring two rings allow data to be sent in
    both directions.
  • This creates redundancy (fault tolerance),
    meaning that in the event of a failure of one
    ring, data will still be transmitted on the other
  • The 802.5 standard is the Token Ring access
    method that is used.
  • FDDI uses light instead of electricity to
    transmit data over a dual ring.

Identifying Network Topologies
  • The mesh topology connects all devices (nodes) to
    each other for redundancy and fault tolerance.
  • It is used in wide-area networks (WANs) to
    interconnect LANs and for critical networks.
  • The mesh topology is expensive and difficult to

Identifying Network Topologies
  • The hybrid topology combines more than one type
    of topology.
  • When a bus line joins two hubs of different
    topologies, the configuration is called a star
  • The bus line is used to transfer the data between
    the star topologies.

Media Types
Networking Media
  • Networking media can be defined simply as the
    means by which signals (data) are sent from one
    computer to another.
  • This includes cable or wireless means.
  • There are a wide variety of networking media in
    the marketplace.

Twisted-Pair cable
  • Twisted-pair is a type of cabling that is used
    for telephone communications and most modern
    Ethernet networks.
  • A pair of wires forms a circuit that can transmit
  • The pairs are twisted to prevent cross talk.
  • Pairs of copper wires that are encased in
    color-coded plastic insulation are twisted

Twisted-Pair cable
  • Shielded twisted-pair (STP) cable combines the
    techniques of cancellation and twisting of wires
    with shielding.
  • Each pair of wires is wrapped in metallic foil to
    further shield the wires from noise.
  • The four pairs of wires are then wrapped in an
    overall metallic braid or foil.
  • STP reduces electrical noise from cable
    (crosstalk) and from outside the cable (EMI and

Twisted-Pair cable
  • Unshielded twisted-pair (UTP) has two or four
    pairs of wires.
  • It relies solely on the cancellation effect
    produced by the twisted wire pairs to limit
    signal degradation caused by electromagnetic
    interference (EMI) and radio frequency
    interference (RFI).
  • UTP is the most commonly used cabling in Ethernet

Fiber-Optic Cable
  • Fiber-optic cable is a networking medium that is
    capable of conducting modulated light
  • To modulate light is to manipulate it so that it
    travels in the way that it transmits data.
  • It refers to cabling that has a core of glass or
    plastic (instead of copper), through which light
    pulses carry signals.

  • Wireless networks use radio frequency (RF),
    laser, infrared (IR), and satellite/microwaves to
    carry signals from one computer to another
    without a permanent cable connection.
  • Wireless signals are electromagnetic waves that
    travel through the air.
  • No physical medium is necessary for wireless
  • Mobile phones are a common application of

Hubs and Repeaters
  • Typical LAN devices include repeaters, hubs,
    bridges, switches, and routers.
  • A repeater receives the signal, regenerates it,
    and passes it on.
  • Repeaters are used mainly at the edges of
    networks to extend the wire so more workstations
    can be added.

Hubs and Repeaters
  • Using a hub changes the network topology from a
    linear bus, where each device plugs directly into
    the wire, to a star.
  • Data arriving over the cables to a hub port is
    electrically repeated on all the other ports
    connected to the same Ethernet LAN, except for
    the port on which the data was received.
  • Hubs come in three basic types
  • Passive
  • Active
  • Intelligent

Bridges and Switches
  • Bridges and switches operate at the data link
    layer of the OSI model.
  • The function of the bridge is to make intelligent
    decisions about whether or not to pass signals on
    to the next segment of a network.
  • When a bridge sees a frame on the network, it
    looks at the destination MAC address and compares
    it to the forwarding table to determine whether
    to filter, flood, or copy the frame onto another

Bridges and Switches
  • Switches learn certain information about the data
    packets that they receive from computers on the
  • They use this to build forwarding tables to
    determine the destination of data being sent by
    one computer to another on the network.
  • They help segment a network and reduce network
    traffic congestion by limiting each port to its
    own collision domain.

  • Routers operate at the Network layer of the OSI
  • They are slower than bridges and switches but
    make "smart" decisions on how to route packets
    received on one port to a network on another
  • Routers are capable of segmenting the network.
  • Routers are capable of segmenting a network into
    multiple collision domains as well as into
    multiple broadcast domains.

  • Routers can be computers with special network
    software installed on them or they can be other
    devices built by network equipment manufacturers.
  • Routers contain tables of network addresses along
    with optimal destination routes to other
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