Section 5 : Network Cabling

Question 1

What is Ethernet?

Answer 1

• Ethernet is a network protocol that controls how data is transmitted over a LAN.
• It’s referred to as the Institute of Electrical Electronics Engineers (IEEE) 802.3 Standard
• It supports networks built with thin and thick coaxial, twisted-pair and fiber-optic cabling
• The original Ethernet standard supported 10mbs speeds, but the latest supports much faster speeds.
• Ethernet uses CSMA/CD access methodology.
• Ethernet uses a “xx Base T” naming convention
  
  • xx: Speed of cable
  • Base: Baseband communication(Sngle frequency)
  • T: Type of cable

Question 2

list some of the Ethernet xxBaseT naming?

Answer 2

10BaseT: 10mbps Twisted-Pair Standard Ethernet

10BaseF : 10Mbps Fiber Optic Standard Ethernet

100BaseT: 100Mbps Twisted-Pair Fast Ethernet

100BaseF : 100Mbps Fiber Optic Ethernet

1000BaseT: 1Gbps Twited Pair Gigabit Ethernet

1000BaseF : 1Gbps Fiber Optic Gigabit Ethernet

Question 3

What is Twisted-Pair Copper Cabling?

Answer 3

• 4 Twisted Pairs of Wires with RJ-45 Connector
• Balanced pair operation
  
  • • & - Signals
  • Equal & Opposite Signal
• Why are they twisted?
  
  • To help Reduce interference
    
    • Crosstalk
    • Noise(Electromagnetic Interference)
• ​​Security concerns
  
  • ​Signal Emanations
    
    • ​Any modulated signal (sound or electromagnetic radiation) leaking from a device that may be used to reconstruct information being processed or transmitted by that device. (EMSEC and TEMPEST.)
• 100 Meters Maximum Distance
  
  • Signal Attenuation
    
    • ​Loss of signal power in a transmission. Often abbreviated “ATTN.”

Question 4

Shielded vs. Unshielded & EMI?

Answer 4

• Unshielded Twisted Pair (UTP)
  
  • More susceptible to electromagnetic interference (EMI).
• Shielded Twisted Pair(STP)
  
  • Less susceptible to EMI & Crosstalk (if each pair shielded)
• Electromagnetic Interference(EMI)
  
  • The disruption of the operation of an electronic device when it’s in the vicinity of an electromagnetic field caused by another electronic device (manufacturing equipment, microwave ovens, etc.).

Question 5

What is the Role of Twists in Twisted Pair Cables?

Answer 5

Increased twists per inch:

• Reduces Crosstalk
• Increases Signals
• Support Faster Speeds

Question 6

What are the Copper Cable Categories?

Answer 6

• Category 3(CAT 3)
  
  • 10Mbps Speed Rating
• Category 5 (CAT 5)
  
  • 100Mbps Speed Rating
• Category 5e (CAT 5e)
  
  • 1Gbps Speed Rating
• Category 6 (CAT 6)
  
  • 1Gbps Speed rating
  • 10Gpbs Speed rating (Shorter Runs)
• Category 6a(CAT 6a)
  
  • 10Gbps Speed rating

NB: All categories limited to 100 meters maximum length before suffering from signal attenuation.

Question 7

What are the Copper Wiring Standards?

Answer 7

• Two standards
  
  • T-568A
  • T-568B
• The newer and recommended standard T-568B
• Either can be used.
• Why are standards important?
  
  • Lower costs
  • Increase interoperability
  • Easier maintenance

Question 8

What are the 2 Types of twisted Pair Cables?

Answer 8

Straight-Through Cable:

• Connecting “Unlike” Devices
  
  • Computer to Switch
  • Switch to Router

Crossover Cable:

• Connecting “Like” Devices
  
  • ​Router To Router
  • Computer To Computer

Question 9

What is a Plenum?

Answer 9

• The plenum is the open space above the ceiling or below a raised-floor.
• A”plenum-space” is the part of a building that enables air circualtion by providing pathways for heated/air-conditioned and return airflows at a higher pressure than normal
• All network cabling placed in the plenum should be “plenum-rated”

Question 10

Non-Plenum-Rated & Fire Hazard?

Answer 10

• Non-Plenum cable or polyvinyl chloride (PVC) cable is often less much less expensive than plenum cable.
• When PVC burns or smolders it releases toxic fumes into the air (Hydrochloric Acid and Dioxin)
• A plenum air return would unknowingly circulate toxic air throughout an office
• Spinkler systems cannot typeically access pelum area.
• Building codes often requires Plenum Rated cable installed through any pelnum air return space.

Question 11

What are Plenum-rated Cables?

Answer 11

• Plenum-Rate cables have a special insulation (Teflon Coated) that has low smoke, low flame and non-toxic characteristics.
• If they catch fire, they won’t rlease toxic fumes.

Question 12

What is Fiber Optic Cabling?

Answer 12

• Fiber optic comes in a form of glass or plastic fiber:
  
  • High bandwidth
  • Long distances
  • Immune to Electromagnetic Interference(EMI)
  • Doesn’t Emanate Signals
• There are Two Types of Fiber:
  
  • Multi-Mode Fiber(MMF)
    
    • Shorter distances(LAN/ Building-to-Building)
    • Up to 1 Miles (1.6 KM)
  • Single-mode Fiber (SMF)
    
    • More expensive than multi-mode
    • Longer distances (WAN, Across Town)
    • Up to 25 miles (40 KM)

Question 13

Why use Fiber?

Answer 13

• Fiber cable is more expensive than twisted pair, as is the equipment
• You can perform much longer network cable runs with fiber.
  
  • 100 meters (Twisted Pair) versus up to 40 KM (Fiber)
• You have decreased network equipment costs
  
  • Switches, routers (With Twited pair you would need a switch every 1oo meters)
• Fiber is:
  
  • Immune to EMI and Signal emanations
  • has lower signal attenuation
  • making more reliable and secure

Question 14

What are the Fiber Optic Cable Characteristics?

Answer 14

Cable Type: Speed Distance Core

===========================================

Single-Mode 10Gbps 40 KM Glass Core

Multi-Mode 10Gbps 300 Meters Plastic Core

Multi-Mode 1Gbps 550 Meters Plastic Core

Multi-Mode 100Mbps 1.6 KM Plastic Core