Chapter 7 – Network Cabling

 

  1. What two qualities does one concern oneself with in cable requirements of network cabling?

a) Signal strength

b) Quality of the signal

 

  1. What is attenuation, and how is it specified in copper and fiber?

@Attenuation is the lost of signal power over the length of a cable

a)      Copper: Attenuation is normally measured as a number of decibels per 100 ft.

b)     Fiber Optic: Decibels per kilometer

 

  1. What affects attenuation in copper cables?

@Capacitance of the cable or heat affects attenuation in copper cables

 

  1. If the opposition of current flow, impedance, is not consistent, what happens to the signal?

@If opposition of current flow, impedance, is not consistent, a portion of the data signals can be reflected back down the cable, often causing errors in the data transmission

 

  1. What does capacitance filter out?

@Capacitance filter out high-frequency signals

 

  1. What does a distorted or rounded data signal cause?

@A distorted or rounded data signal causes a high bit error rate (BER) or causes data to be received in error

 

  1. Electromagnetic induction causes what type of problem?

@Crosstalk contaminates adjacent lines and can cause interferences, overloaded circuits, and other similar problems

 

  1. List the three types of shields used to prevent crosstalk.

1.      Longitudinally applied metallic tape

2.      Braided conductors, such as are commonly used in coaxial cables

3.      Foil laminated to plastic sheets

 

  1. What type of transmission is used to minimize crosstalk in unshielded cables?

@Most of today’s cables use twisted pairs and balanced transmission to minimize crosstalk.

 

  1. Matching: Match each wire with the appropriate application, advantage, and disadvantage.  Each of the wires listed will have three numbers indicating these elements.

 

 

 

                                             Applications              Advantages                        Disadvantages

Coaxial cables           Original Ethernet               Better data security               Bulky

Unshielded (UTP)     Most current networks         Inexpensive                          Limited bandwidth

      Optical fiber cables  Optional for most network   Excellent bandwidth              High cost

      Screened (TP)            Same as UTP                                Has no effect on crosstalk     Hard to terminate

      Shielded (STP)           IBM Token Ring                    Easy installation                Breaching security

 

 

  1. What type of cabling is needed for wireless transmission?

@In a wireless network, no data transmission cables are required to connect any individual terminal.

 

12.    What is the advantage of wireless networks?

@Advantage of wireless network is that they can be set up anywhere, almost instantly

 

13.    You can use Cat 3 and Cat 5 components together, since the wires are so similar in color and size. T/F?

@False.  You cannot mix Cat 5 and Cat 3 components

 

14.    What type of terminations are used in wiring closets?

@In wiring closets, termination may be either punchdowns or patch panel or both, depending on the destination of the cables

 

15.    What is the procedure in pulling horizontal cables?

@The procedure in pulling horizontal cables involves gaining access, determining the best route for the cables, running a handline, affixing cables to the handline, and pulling the cables

 

16.    Once you have each box of cable in the drop area, what should you do to each box?

@Once you have each box of cable in the drop area, you should mark each as to the final location

Post-it notes are good temporary labels for the boxes

 

17.    How do you support the wires above the ceiling?

@Above the suspended ceilings, “J” hooks can be used to separate the cables from most other hardware above the ceiling, especially power cables and lighting fixtures.

 

18.    When you run cable through a conduit, what can you use to protect the cable from the rough area at the end where the conduit was cut?

@When you run cable through a conduit, you can use a special “leaderguard” to prevent cable damage

 

19.    When placing both fiber and copper cables in a cable tray, which type of cable is placed on the bottom?

@When placing both fiber and copper cables in a cable tray, copper cables should go to the bottom and the fiber cables should be on top.

 

20.    For long-run riser installations, you would use special cables or install a __________.

@For long-run installations, you would use special cables or install a “messenger” (A steel cable to which the cable can be attached), is installed with anchors at top and bottom to which the cables are attached.

 

21.    What will help in a riser “pull” to get the cable to the end destination?

@A riser “pull”, it is much easier to drop the cable down from the top and let gravity help you

 

22.    What should be done in the closets or equipment room before pulling the cable?

@In the closet or equipment room, all hardware should be installed before any cabling begins.

           

23.    What will help speed the process of a setup in a closet or equipment?

@Good documentation is mandatory to speed the setup and moves and changes

 

 

Chapter 8 – Testing Voice, Data, and Video Wiring

 

  1. What is used as a simple coax tester?

@Digital multimeter (DMM) can be used as a simple coax tester

 

  1. What should you look for if there is a problem with a coax cable transmission?

@If a coax cable transmission occurs, look for damage like kinks that may be causing the problem.

 

  1. What UTP test instruments do you use to test low-speed wire or Cat 5 high-speed wire for correct connections?

@Wire mapper or a “toner” is used to test low-speed wire or Cat-5 high-speed wire for correct connections

 

  1. Why is Cat 5 better choice to install than Cat 3?

@Since the incremental cost of Cat 5 over Cat 3 is low and the installation of Cat 5 everywhere gives the most future flexibility, Cat 5 is a better choice to install then Cat 3.

 

  1. What is used to test wire mapping, length, attenuation, and NEXT?

@Automated loss testers are used to test wire mapping, length, attenuation, and NEXT.

 

  1. What are the colors ude in the 4-pair UTP cable?  List the pairs togetherr.

@Wht/Org, Orange; Wht/Grn, Grn; Wht/Blu, Blu; Wht/Brn, Brn

 

  1. Other than the EIA/TIA 568A or EIA/TIA 568B, what variations are used but not recommended for structured cabling?

@Open DECconnect is a variation of T568A that leaves out pair 1

 

  1. What company’s standard established 568B wiring?

@AT&T established the T568B wiring.

 

  1. What is most important in any cable?

@In any cable, correct connection is the most important .

 

  1. What does a time domain reflectometer (TDR) test?

@Time Domain Reflectometer (TDR) shows the distance to the fault.

 

  1. What happens in a split pair?

@In a split pair, one wire on each of two pairs is reversed on both ends.

 

  1. What is impedance?

@Impedance is the “resistance” of the cable at the frequency of signals transmitted.

 

  1. What are reflections that occur at changes in impedance?

@Return loss refers to reflections that occur at changes in impedance.

 

  1. What is it when the cable has a reflection from a variation in impedance in the cable?

@When the cable has a reflection from a variation in impedance in the cable, it’s called, structural return loss.

 

 

  1. How much untwisting is allowable before you lose performance in Cat 5 cable?

@˝ inch, or 13 mm in allowed for untwisting before you lose performance in Cat 5 cable.

 

  1. What do you need to know to use a time domain reflectometer (TDR) to calculate the length of a cable?

@To use a Time Domain Reflectometer (TDR), you need to know the characteristics speed of the signal in the cable, called the nominal velocity of propagation (NVP), and the roung-trip transit time, so you can calculate the length of the cable.

 

  1. What is reduced by the different twist rates in the  separate pairs of UTP cable?

@Different twist rates in the separate pairs of UTP cable is designed to minimize (reduce) crosstalk.

 

  1. Matching: Match the fault with the return pulse indication of a TDR.

A) Open at the end = Same polarity as the transmitted pulse

B) Properly terminated = No return pulse

C) Shorted = Opposite polarity to the transmitted pulse

 

  1. Near end crosstalk (NEXT) is when the transmitting pair couples part of its signal to other pairs of wires. T or F?

@False. The most common failure for NEXT is improper termination.

 

  1. What does power sum NEXT measure?

@Power sum NEXT measures crosstalk on one pair while all other pairs are transmitting.

 

  1. What occurs in a delay skew and propagation delay?

@In a delay skew and a propagation delay, a signal will take different times for end-to-end transmission for each pair, and NVP can also vary with wire insulation, also causing differences in transit times.

 

  1. Different insulation in a Cat 5 wire does not affect the performance of the wire.  T or F?

@False.  Different insulation in a Cat 5 wire affects the performance of the wire by widely varying NVP

 

  1. What are the specifications for a cable plant length for a link and a channel?

@Specifications for a cable plant length requires:

    1. The link be less than 94 meters
    2. The channel to be less than 100 meters, including the test equipment patchcords.

 

  1. What does a channel include that a link does not include when dealing with length?

@The channel performance specification include two additional connections on either end that a link does not when dealing with length.