Chapter 4 – Cisco Semester I

Wiring Closets

IDF and MDF

Metrics

Behavior Objective

• Stress importance of good documentation

• Stress adherence to wiring Do’s and Don’ts

–Students will document work

–Students will follow standard procedures

Learning Objective

• Develop knowledge base to enable students to design networks that perform well

Students will learn design conceptsStudents will gain confidence completing wiring tasks

Content

• Network Design• Topologies

– Logical• Token Ring (single ring)

• FDDI (dual ring)

• Ethernet (logical bus) – largest % of installations

– Physical• Star and Extended Star

– Both Ethernet and IEEE specify Star

» Extended Star requires additional wiring closets

Content Continued

• Wiring and electrical standards– ANSI– EIA/TIA 569-A– ISO/NEC

• Wiring closet specifications

• Medium– CAT 5 UTP for horizontal cabling

Why CAT 5 UTP

• Easy to use (not too thick but thick enough to hold up – unlike cheap net)

• Twists provide cancellation effect

• Relatively inexpensive– Specified by both IEEE and Ethernet

Ethernet Network Speeds

• 10Base T

• 100 Base TX (aka Fast Ethernet)

• 1000 Base T (aka Gigabit)

Documentation Required

• Organization Information– Who will use, computer skill level, network knowledge

base, tasks performed

• Analysis and Problem Solving Information Gathered

• Cut Sheet – diagram floor plans• Logical Design Map – IP addresses• Physical Design Map – MAC addresses (devices),

cable runs, outlets, etc.

DEVICES

• Layer 1– Hubs, repeaters (extend run beyond 99 meters)– Transceivers – connect unlike devices

• Layer 2– Bridges -- reduce congestion and collision domain– Switches – also provide virtual LAN and larger

bandwidth

• Layer 3– Routers – segmentation – divide network into

segments; reduce broadcast domain

Ground Basics

• Grounds are critical– Can minimize ESD problem

• Remember ESC can destroy semiconductors and data• Safety ground can prevent high voltage buildup• GFCI (Ground Fault Circuit Interrupt)can cause circuit breaker

to stop flow of electrons

• Grounds connected to chassis are not enough to protect computers and networks– Also need UPS (Uninterrupted Power Supply)– And Surge Protector

Wiring Basics

• One Hand Rule– Keep one hand in pocket when working with electrical

devices to avoid creating a circuit with your body as the connection

• Electrical Current through the heart can kill

• Common Fault– Hot Wire and Safety

• Normal Fault– Hot Wire and Neutral Wire

Wiring Closet Specifications

• Near POP – to connect to outside world

• Centrally located – to minimize length of horizontal cable runs

– More important than being near POP• Large enough to allow for expansion

• Raised floor– To bring in horizontal cabling from work areas

Wiring Closet Continued

• Tile Floor– Reduce dust, minimize static electricity

• No Dropped Ceiling– Security

• Fire-Rated Plywood on Interior Walls– Minimize fire risk (1.9 cm thick – 4.4 cm from wall)

• Controlled Humidity (30-50%)• Controlled Temperature (21 C or 70 F)

More Wiring Closet Specs

• .9 Meter door that opens to hall– Locked from outside but controlled from inside

• 50 candle foot lighting (preferably not fluorescent) – 2.6 meters above floor

• Light switch immediately inside door

• Two dedicated non-switched circuits

• Outlets every 1.8 meters (6 feet)

And Still More Closet Specs

• Ladder Rack to support Patch Panel

• Sufficient Floor Load capacity to bear weight of devices

• Ceiling and wall openings sealed with fire retardant material

Important Wiring Closet Info

• Need a wiring closet on every floor• Need a wiring closet for every 1000 square

meters of floor space• Maximum length of horizontal cabling is 90

meters• Add 3 meters to attach work station and 6

meters to attach to patch panel – Total length – approx 100 meters

Multiple Wiring ClosetsStructured Wiring

• Designate primary wiring closet as MDF – Multiple Distribution Facility– Hubs and Patch Panel in MDF or IMF– Routers, switches, WAN connection in MDF

• Floor load requirements higher than IDF

• Vertical cabling (Backbone) will connect other wiring closets (IDF – Intermediate Distribution Facility)

MDF and IDF Location

• Good location can minimize horizontal cable runs

• Chosen location should minimize environmental problems

• Chosen location should make it easy to install and maintain network

Structured Wiring

• MDF known as Main Cross Connect• Can have two levels of IDF (Intermediate)• When there is only one level

– IDF Horizontal Cross Connect

• When there are two levels– IDF connected to MDF is Intermediate Cross Connect

• Other IDFs connected to workstations are HCC– There can be only one level between IDF for work stations and

MDF

MDF – IDF Cabling

• Aka Backbone CablingBetween Buildings (InterBuilding) -- Single Mode Fiber preferred – 3000 metersWithin Building (Intrabuilding)

MultiFiber 62.5/125 u is recommended (568A) – 2000 meters – USED MOST OFTEN

Other options (not preferred and not extensively used)100 ohm UTP (four pair)150 ohm STP (two pair)

Coaxial cable is not recommended

Why Fiber for Backbone?

• Eliminates Problems Caused By:– Different Voltage Potential in circuits served by

different transformers (a grounding problem)• Different transformers can serve circuits in same

building

– Electrical strikes that could hit cabling between buildings

• Backbone includes connection to POP and Wiring Closets (from Patch Cords)

Special Backbone Considerations

• Run wire through conduit or sleeve

• If unable to run under floor– Run sleeve above door level

• Total distance from MDF to workstations can’t exceed 3000 meters for single mode or 2000 for multimode fiber

Metric Reminder

• 1 Meter is approximately 39.?? Inches

• 1 decimeter = 1/10 meter

• 1 centimeter = 1/100 meter

• 1 millimeter = 1/1000 meter

• 10 meters = 1 decameters

• 100 meters = 1 hectometer

• 1000 meters = 1 kilometer