Hands On Networking Essentials

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					Networking Media (Tangible)




                          1
Learning Objectives
   Define and understand technical terms
    related to cabling, including attenuation,
    crosstalk, shielding, and plenum
   Identify three major types of both network
    cabling and wireless network technologies
   Understand baseband and broadband
    transmission technologies and when to use
    each



                                                 2
                                           continued
Learning Objectives
   Decide what kinds of cabling and connections
    are appropriate for particular network
    environments
   Describe wireless transmission techniques
    used in LANs
   Describe signaling technologies for mobile
    computing




                                              3
Network Cabling:
Tangible Physical Media
   Provides a medium across which network
    data can travel in the form of a physical
    signal, whether it is a type of electrical
    transmission or some sequence of light
    pulses




                                                 4
Primary Cable Types
   Coaxial cable
   Twisted-pair (TP) cable
     Unshielded (UTP)
     Shielded (STP)
   Fiber-optic




                              5
    General Cable Characteristics
   Bandwidth rating
      Number of bits that can be transferred per
       second
   Maximum segment length
      Signals weakens along with the distance they
       travel
      Weakened signals should be restored
   Maximum number of segments per internetwork
      Networks are subject to some kind of
       maximum tolerable delay, after which it’s
       assumed signals can no longer arrive

                                                      6
                                                continued
    General Cable Characteristics
   Maximum number of devices per segment
      Each  device insertion will typically cause
      signal attenuation on a cable segment and
      this is called insertion loss
   Interference susceptibility
      Each  type of cable may be susceptible to
       other signals that may be present in the
       environment, e.g., electromagnetic
       interference (EMI) or radio frequency
       interference (RFI)
      We assume 4 levels of susceptibility,
       namely, none, low, moderate, and high
                                                           7
                                                     continued
General Cable Characteristics
   Connection hardware
     Differentcables are associated with different
      connectors
   Cable grade
     The  rate of a cable in transferring data
     Building and fire codes may require specific
      cabling requirements such as the
      combustibility and toxicity of the sheath
      material of a cable, as well as the insulation
      that cover the cable
     Plenum-rated cable is of low combustibility
      and it generates relatively nontoxic fumes
      when burned                                       8
                                                  continued
General Cable Characteristics
    Bend radius
      Bending  of cable of certain types is more
       prone to damage than others
    Material costs
      Some     cable is more expensive to build than
       others
    Installation costs
      Labor and auxiliary equipment can easily
       cost more than the cable when installing a
       network


                                                        9
Primary Techniques for
Sending Signals across a Cable
   Baseband transmission
   Broadband transmission

   This has nothing to do with broadband and
    narrowband internet connections.




                                                10
Baseband Transmission
   Uses digital signals sent over a cable without
    modulation
   Sends binary values (0s and 1s) as pulses of
    different voltage levels (i.e., digital
    transmission)
   Entire bandwidth of the cable is used to
    transmit a single data signal
   Limits any single cable strand to half-duplex
    transmission

                                                  11
                                             continued
Baseband Transmission
   Signal flow can be bi-directional
   Uses repeaters to restore the signal to its
    original strength and quality before
    retransmitting it to another cable




                                                  12
Broadband Transmission
   An analog transmission technique which may
    use multiple communication channels
    simultaneously
   Each data channel is represented by
    modulation on a particular frequency band,
    for which sending or receiving equipment
    must be tuned, like a TV set
   Signal flow is one-way only; two channels
    are necessary for computers to send/receive
    data


                                                13
                                           continued
Broadband Transmission
   Primary approaches to supporting two-way
    broadband communications
     Mid-splitbroadband
     Dual-cable broadband
   Uses amplifiers to detect weak signals,
    strengthen those signals, and then
    rebroadcast them; noise may be amplified
    too
   Offers higher bandwidths, but generally
    more expensive than baseband systems

                                               14
Coaxial Cable
   Uses a center
    conductor – wrapped
    by an insulating
    layer, surrounded by
    a braided wire mesh
    and an outer jacket
    or sheath -- to carry
    high-bandwidth
    signals such as
    network traffic or
    broadcast television
    frequencies
                            15
Coaxial Cable
   Uses shielding to increase the viability of the
    signals that pass through a cable by
    absorbing stray electronic signals or fields
   Less susceptible to interference and
    attenuation than twisted-pair cabling, but
    more so than fiber-optic
   A connector must cap each end of the cable,
    and a terminator must screw into each end



                                                 16
Types of Coaxial Cable for
Ethernet
   Thin Ethernet (thinnet, thinwire, cheapernet,
    10Base2)
   Thick Ethernet (thicknet, thickwire, 10Base5)




                                               17
Thinwire Ethernet
   Thin, flexible cable about 0.2” in diameter
   Easy to work with
   Relatively inexpensive to build or buy
   Well suited for small or constantly changing
    networks
   Uses BNC T-connectors to attach directly to
    networking devices and computers’ network
    adapter cards


                                               18
Thinwire Ethernet




                    19
Radio Government (RG)
Specifications
   Coaxial cable designation that reflects coaxial
    cable’s original use as a conveyance for radio
    frequency data and signals




                                                 20
Radio Government (RG)
Specifications




                        21
Thinwire Ethernet Cable




                          22
Thickwire Ethernet
   Uses a rigid cable about 0.4” in diameter
    (“frozen yellow garden hose”)
   Rarely used except as a backbone for a new
    network installation (due to expense, large
    diameter, and lack of flexibility)
   Uses a vampire tap to attach a device to the
    cable, which in turn attaches to a
    transceiver; transceiver attaches to a drop or
    transceiver cable that plugs into an
    attachment unit interface (AUI)


                                                23
Attaching to
Thinwire Ethernet Cable




                          24
Attaching to
Thickwire Ethernet Cable




                           25
Running Thickwire Cable




                          26
Thickwire Ethernet Cable




                           27
Coaxial Cable Characteristics
   Can handle moderate to serious bandwidth
   Supports intermediate to moderately long
    cable runs
   Relatively affordable
   Resistant to interference; relatively safe from
    electronic “eavesdropping”




                                                 28
Twisted-pair Cable
   Consists of one or more pairs of insulated
    strands of copper wire twisted around one
    another
   Importance of twists
     Improve  resistance to interference
     Limit the influence of crosstalk




                                                 29
Types of TP Cable
   Unshielded twisted-pair (UTP)
       Contains one or more pairs of insulated wires within an
        enclosing insulating sheath
       Follows the ANSI/EIA/TIA 568 standard
       Prone to crosstalk
   Shielded twisted-pair (STP)
       Encloses each pair of wires within a foil shield, as well
        as within an enclosing insulating sheath
       Supports higher bandwidth over longer distances than
        UTP
       Has no set of standards


                                                                30
Types of TP Cable




                    31
UTP cable (1/3)
   Most popular form of local area network cable
   UTP cables are classified to a number of categories
    such that each of them is associated with a different
    specification which include its maximum data
    transmission speeds




                                                            32
UTP cable (2/3)
   Category 6 UTP cable can support up to 1 gigabit per
    second, with signaling rates up to 250 MHz;
    specification of category 7 UTP cable is being drafted
   UTP is particularly prone to crosstalk and the
    shielding included with STP is designed specifically to
    alleviate the problem
   Like STP, it employs RJ-45 telephone connectors to
    plug into computer network interfaces or other
    networked devices




                                                         33
UTP cable (3/3)
   Keep cables run within 295 feet
   For more information and FAQs about UTP cable, see
    http://www.lanshack.com/cat5e-tutorial.asp




                                                    34
Twisted-pair
Network Cabling Schemes
   Commonly employ RJ-45 telephone
    connectors




                                      35
10BaseT’s Networking
Characteristics




                       36
Fiber-optic Cable
   Uses pulses of light sent along a light-
    conducting fiber at the heart of the cable to
    transfer information
   Sends data in one direction only; two cables
    are required to permit data exchange in both
    directions
   Consists of a slender cylinder of glass
    fiber(s), called the core, surrounded by a
    concentric layer of cladding material and
    then by an outer sheath


                                               37
 Fiber-optic Cable

Kevlar® is a kind
of nylon that is
used makes
bullet-proof vest
and puncture
resistant bicycle
tires.



(See http://www.psrc.usm.edu/macrog/fiberopt/of.htm for
more information about what optic fibers are made of.)
                                                          38
Primary Types of
Fiber-optic Cables
   Single-mode cables
     Include only one glass fiber at the core
     Cost more
     Work with laser-based emitters but span the
      longest distances
   Multi-mode cables
     Incorporate   two or more glass fibers at the
      core
     Cost less
     Work with light emitting diodes (LEDs) but
      span shorter distances (< 2 km)
                                                      39
Fiber-optic Cable Advantages
   Immune to interference
   Highly secure; eliminates possibility of
    electronic eavesdropping
   Good medium for high-bandwidth, high-
    speed, long-distance data transmissions




                                               40
Fiber-optic Cable Drawbacks
   High cost to install
   Difficult installation
     Cable must be precisely polished on the cut ends
     Cables are sensitive to bending or shearing forces
     Sophisticated optical tests are needed to ensure
      proper cable alignment to sensors and emitters
     Fiber-optic system's incompatibility with current
      electronic hardware systems requires that
      communication hardware systems be somewhat
      retrofitted to the fiber-optic networks. Much of the
      speed that is gained through optical fiber
      transmission can be inhibited at the conversion
      points of a fiber-optic chain.
                                                             41
Fiber-optic Cable
Characteristics




Remark: The maximum bandwidth of an optical cable has
been increased tremendously over years. Some can support
more than 1 terabit per second.
                                                       42
Fiber-optic Media Connectors
   Number of connector options for fiber-optic
    media varies with the type of light-emitting
    source and light-detecting sensors being
    used
     ST (straight tip)
     SC (straight connection)
     MIC (medium interface connector) for FDDI
     SMA (subminiature type A)




                                                   43
Reference Website for Fiber-
optic Data Communications
   For more information about fiber-optic data
    communications, visit
    http://www.lascomm.com/tutorial.htm
    Specifically, read the section on wave
    division multiplexing.




                                                  44
    Cable Selection Criteria
   Bandwidth
   Budget
   Capacity (data, bandwidth)
   Environmental considerations
   Placement
      Where   will the cables run?
   Scope
      Number     of devices to be connected to the
      network
   Span
      Distance   that the network needs to span
                                                      45
Comparison of General Cable
Characteristics




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