Physical Layer Limitations and Importance

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Physical LayerLimitations and Importance

• By
• Grace, Alex, Mark
• Guest Prof. Ali Notash

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Outline

• Fiber Optic
• Cable Termination
• Attenuation
• Cable Installation
• Signal Modulation
• NIC Jumpers
• Importance of Physical Layer

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5. Fiber Optics

• Fiber Optics technology use modulated light to
  quickly transmit data over great distances
  through insulated glass fiber-type material.
• Fiber Optic need to be protected against tensile,
  torsion, and bending stresses.
• The glass fibers are very susceptible to
  twisting, which can compromise its integrity.

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1. Cable Termination

• Pin-out and the 3,6 used to transmit and receive
  568A, 568B, 568-A (At T)
• Maintaining twists how to cancel
  electromagnetic fields, to prevent near- end,
  and farend crosstalk.
• Not over-stripping insulation, and shielding
  prevent interference from outside sources.
• The best types used are stranded for patch cords,
  solid core for infrastructure, and the 2 types
  of RJ45 terminators (flat blade and 3 prong).

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2. Attenuation

• Loss of signal on
• -24 AWG twisted pair
• -CAT 3 and CAT 5, characterized by
  impedance,capacitance of wire, inductance of
  wire and number of twists for canceling fields.
• The effects of distance limitation of wire on
  electrical signal.

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3. Cable Installation

• Poor cable installation is caused by
• - Pulling cable with too much force
  (gt25 pounds)
• - Pulling twists out of wire
• - Not spooling correctly, results in kinking
  (violating bend radius of cable in hidden areas)
• LAN cable testers check wire-mapping, NEXT and
  FEXT to determine quality of cable installation.

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4. Signal Modulation

• Signal Modulation is the changing of signal so
  that it varies at different pattern.
• This can be done in two ways, analog and digital.

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5. NIC Jumpers

• New styles of Nic Jumpers use flash, just like a
  router.
• Elevated voltages used to write EEPROM to set
  flip-flops so that EEPROM can act as a ROM

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Importance of Physical Layer

• Fiber Optic Systems offer high security because
  they do not induce or emit any external energy.
  A signal loss can be detected immediately as long
  as they system is monitored.