Structured Cabling Project by dandanhuanghuang


									Ch 9. Structured Cabling Project

     Laboratorium Telematika - ITB
     Cisco Regional Networking Academy
     Semester 1
     Version 2.1.1

     Duration: 45 minutes

   Focuses on standards for networking media.
     TIA/EIA 568A - cabling standard.
     TIA/EIA 606 - labeling standard.

   Techniques for dressing and securing the
   RJ45 jacks, wiring sequence.
   Wiring closet design.
   Equipment found in a wiring closet.
     patch   panels, hubs, bridges, switches, & routers.

Planning/Designing a Network
    Safety codes
    Documentation
    Task division
      Occasionally alternate jobs to develop
       networking installation skills.
    Create a flowchart
      Include   a timeline for important tasks.
    Schedule materials flow
      Materials,   suppliers, tools.

TIA/EIA 568A Standards
    Defines horizontal cabling.

Telecommunications Outlet
    Telecommunications
     outlets are wall

    TIA/EIA 568A
     specifies that an RJ-
     45 jack must be
     used for making
     the connection to
     Cat 5 UTP.

RJ45 Mounting
   Two types of wall mounts:
     Surface    mounting (easier to install, concrete
        Screw-mounted box.
        Adhesive-backed box (easier, but cannot be
     Flush    mounting.
   Surface mounting is generally preferred.
            lower labor costs.
     Faster,
     Maybe the only option in some cases.

Flush Mounting Concerns
    Type of wall material.
      Plaster   tends to crumble, has wood lath backing.
      Wood
         More  solid support.
         Can install in baseboard, but avoid lower 5cm (2”)
          - need to clear wall’s bottom plate or framing.
         Avoid door and window trims.

      Drywall   - obstructions due to studs every 18-24”.
         Check  with small hole for obstructions.
         Select position 30-45cm (12-18”) above floor.

         Level.

Flush Mounting Concerns (cont.)
    Type of mounting
      Box;
      Low-voltage   bracket.
    Safety Precautions
      Any  time you are working in walls, ceilings, or
       attics, it is extremely important that you
       remember to turn off the power to all circuits
       that go to, or pass through, the work area.

Wires in RJ45 Jack
    Performance is closely linked to the quality of
     the wire connections.
    Do not strip off any more of the jacket than
     needed, about 2.5cm (1”).
      Removing  too much jacket insulation can slow
       data throughput.
    Arrange wires in proper order.
    Keep wires centered in jack.
      If   skewed, data throughput can decrease.
    Use punch tool to “punch down” wires into jack.

Tips in Installing Cable
    Maintain twists as close as possible to
     termination (max 13mm (1/2”) for Cat 5 UTP).
    Min bend radius is 4 times the diameter of
     cable; never exceed a 90° bend.
    Use cable ties or velcro straps to secure cable,
     loosely. Do not use staples!
    Avoid stretching cable, 11.3kg (25 lb) of pull
    Leave slack in cable, to reach floor and 60-
     90cm (2-3 ft) in each direction.

Tips in Installing Cable (cont.)

Documenting Cable Runs
   Documentation is useful when upgrading or
    modifying the network in the future.
   Cut Sheet - diagram of cable runs.

    TIA/EIA 606 specifies labeling.
      Unique identifier required on each termination
       hardware unit or on label.
      Cables are labeled at both ends.

    Use unique and descriptive labeling.
      Ex.   Rm 516 West Wall
    Labeling is designed to help diagnosis and
     location of problems.
    All labels must meet legibility, defacement, and
     adhesion requirements (UL969).

Cabling Runs
    Run all cables at once, if you need 4 cables,
     use 4 rolls and pull them all at the same time.
    Mark each cable
     end (3 times).
    Tape cables together
     to pull string.
    Label cable ends
     before cutting the

Routing Cables
    Easiest way is to mount cables on wall.
      Use   tie-wraps to attach cables to walls.
         Adhesivetie-wraps - cannot be moved.
         Screw mounted tie-wraps - can be moved later.

   Raceways - wall mounted channels with
    removable covers.
   Two types:
     Decorative    raceways
        Finished   appearance for use in visible areas.
     Gutter
            hold several cables.
        Will

        Used in attics, dropped ceilings, etc.

   Raceways can be adhesive-backed or screw
     Adhesive-backed      - easy to install, easy to
      remove.                                              17
Raceways (cont.)

Cables in Existing Raceways
    Do not run cables next to power lines or in
     existing raceways with power lines.
      Causes   EMI (electro-magnetic interference).

Safety Precautions
    Turn off power to all circuits in work area.
        unsure, turn off all power.
      If
      Never touch power cables.

    Know locations of fire extinguishers.
    Long pants and sleeves for protection, but avoid
     baggy clothing.
    Survey the area - especially dropped ceiling
    Wear eye protection.
    Be aware of hazards like lead, PCBs or
    Keep work area orderly and neat.               20
Building Safety and Codes
    Find out local building codes.
    Be aware of any restrictions to drilling or cutting
     holes in fire walls or ceilings.
    Holes may need to completely filled with non-
     combustible patching compounds.
    Fire-rated cable must be used in spaces where
     air is circulated.

Horizontal Cabling Supports
    In dropped ceilings, do not lay cable on top of
      Use  wall mount gutters, tie wraps or ladder racks
       to support cables.

Other Tools
    Telepole
      Telescoping   pole used to string cables.
    Fish Tape
      Used   to run cables thru a wall.
    Remember to leave extra (excess) cable in the
     walls and ceilings!

What is a Wiring Closet?
    Wiring closet serves as a central junction point
     for the wiring and wiring equipment used to
     connect devices in a local area network (LAN).
    Center point of star.
    Typical equipment:
      Patch   panels
      Hubs
      Bridges
      Switches
      Routers.

MDFs and IDFs
   Networks can have several wiring closets
    (extended star topology).
   One is designated as the MDF, main
    distribution facility.
   Other wiring closets are the IDFs, intermediate
    distribution facilities.
     IDFs are connected to the MDF, and are
      dependent on it.
     IDFs connect to MDF by backbone cabling.

Horizontal Cabling Connections
    Horizontal cabling usually terminates at the
     patch panel.

Patch Panels
    Provides pin locations and ports.
      Pin locations on back (wires are punched down).
      Ports (RJ45) on the front of panel.
      Wires are color coded, not interchangeable.
         Actual   wire order on the punch down blocks order
          differ from vendor to vendor. Watch for markings
          on the punch down block on the order used for
          T568A or T568B wiring.
    Act as switchboard where horizontal cabling
     from workstation can be connected to other
     workstations or devices.

Patch Panels (cont.)
    Poor connections can cause slower data rates.
      Crosstalk,noise, intermittent electrical
    Arrange wires in ascending order.
             sequence of wires from work area.
      Logical
      Make use of cut sheet.

    Keep wires centered in jack.
      If   skewed, data rate will decrease.
    Avoid exposing too much wire (strip off about
     38-50 mm (1 1/2” to 2”) of jacket).
    Don’t untwist wire pairs more than necessary.
    Use punch tool.                                 28
Patch Panel Mounting
    Most common is distribution rack.
      Easy access to front and back.
      Need to provide 30-45mm (12” - 18”) in back for
       physical access.
    Standard size of distribution rack is .48m or 19”.

Testing Your Network
    1. Break the system into smaller logical groups
     or elements.
    2. Test each group or element.
    3. Note any symptoms or problems.
    4. Determine what the most likely problem
     element is.
    5. Use substitution or additional testing to
     determine if the likely element is in fact the
    6. If not, proceed to the next most likely
     element you suspect.
After finding the problem
    7. When the dysfunctional element is found,
     repair it if possible.
    8. If it is not possible to repair, then replace it.

Network Operations Testing
    IEEE & TIA/EIA have established standards to
     test whether your network is operating at an
     acceptable level.
      Use  this measurement as baseline.
      Baseline is a record of your network's starting
       point or newly installed performance capabilities.
    Continue to test your network on a regular
     basis in order to ensure that it performs at its
      Compare  with the baseline measurements.
      Can spot problems that may be caused by
       aging, poor maintenance practices, weather, etc.
Cable Testers
    Problems may affect all cables
     on a LAN.
    Cable testers certify cables to
     IEEE & TIA/EIA standards.
    Measurable parameters:
      Cable  Distances
      Connectivity.
      Wire maps for crossed pairs.
      Split pairs.
      Signal Attenuation.
      Near-end crosstalk (NEXT).
      Noise level tests.
Measuring Distances
    Max cable lengths are given by TIA/EIA 568A.
    Cable testers use Time Domain Reflectometry
     to measure distance to open or shorted end.
    TDR sends a signal and times its reflection
     back from the end of the cable.
    Accurate to within 61 cm (2ft).

Connection Tests
    Distance measurements can determine
     whether the connections at the patch panels, or
     at the telecommunications outlets, are good.

Correct Wiring
    Wire map shows which wire
     pair connections to what

    Wire map shows:
       12 36 45 78 (near end)
       12 36 45 78 (far end)

Crossed Pairs
    Crossed pairs are
     connected in reverse
     order on one end.
                            Correct Wiring

    Wire map shows:
     21 36 45 78
     12 36 45 78
                            Crossed Pairs

Split Pairs
    Split pairs occurs when wires used for a circuit
     are not from the same pair.
    Split pairs do not have
    Cannot be detected by
     simple wire mapper.
    Can be detected by
     visual inspection or
     by crosstalk
     measurements.                   Split Pairs.

Signal Attenuation
    Attenuation is due to loss of energy in the
     signal (less power).
    Cable testers measure signal from a signal
     injector, attached at far end of the cable.
    Attenuation generally measured at several
      For   CAT 5 cable - up to 100 MHz.
    TIA/EIA 568A specifies allowable losses in
     various types of cables.

Near-end Crosstalk
    Causes of near-end crosstalk.
      Crossed   pairs - most common.
      Untwisting of wire pairs, usually at patch panel.
      Cables too tightly pulled (causing untwisting).
      Too sharp corners (bends) - pairs change
      Split pairs.

    Cable testers measure a series of frequencies
     up to 100Mhz - higher values are better, low
     values indicate problem.

Noise Level Test
    Sources of Interference:
      Fluorescent  lights, televisions, monitors, motors,
       power lines, welders, auto ignitions.
      Radio stations, radar, transmitters.

    Interference sources can be detected by
     knowing the frequency of interference (from
     noise level test).
    Locating sources of outside interference:
      Measure   noise on cable (disconnected from
       computer equipment).
      Trial and error method of turning off electrical
       devices to see which produces the interference.41
   Installing RJ45 jacks.
   Safety concerns:
     1.Turn  off power to area.
     2.Long sleeves, long pants, but not baggy.
     3.Fire extinguisher locations.
     4.Eye protection.
     5.Neatness.

   Documentation.
     Cutsheet - location of cable runs.
     Label cables and terminations.
        UL   969 - legibility, defacement, adhesion.
Summary (cont.)
    Cable installation:
      Mount  cables with tie wraps, velcro; no staples.
      Avoid sharp bends; No stretching.
      Leave slack, service coils.
    Patch panels.
      Actsas switchboard for horizontal cabling.
      Usually mounted on distribution rack.
    Cable Testing.
      Establish   baseline using IEEE & TIA/EIA specs.

The End


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