CCNA 1 and 2 Companion Guide, Revised (Cisco Networking Academy Program) part 94 ppt

Figure A-14 TIA/EIA Structured Cabling Standards ■ TIA/EIA 568-A is the Commercial Building Standard for Telecommunications Wiring.. TIA/EIA-568-B.2 specifies cabling components, transmis

Both the TIA and the EIA are accredited by the American National Standards Institute

(ANSI, section 6.2.7) to develop voluntary industry standards for a wide variety of

telecommunications products This means that many standards often are labeled ANSI/

TIA/EIA The various committees and subcommittees of TIA/EIA develop standards

for fiber optics, user premises equipment, network equipment, wireless communications,

and satellite communications

Although there are many standards and supplements, the following are used most

frequently by cable installers (see Figure A-14)

Figure A-14 TIA/EIA Structured Cabling Standards

■ TIA/EIA 568-A is the Commercial Building Standard for Telecommunications

Wiring The standard specifies minimum requirements for telecommunications cabling, recommended topology and distance limits, media and connecting hard-ware performance specifications, and connector and pin assignments

■ TIA/EIA-568-B is the Cabling Standard This standard specifies the component

and transmission requirements for media TIA/EIA-568-B.1 specifies a generic telecommunications cabling system for commercial buildings that will support

a multiproduct, multivendor environment TIA/EIA-568-B.1.1 is an addendum that applies to four-pair unshielded twisted-pair (UTP) and four-pair screened twisted-pair (ScTP) patch cables bend radius TIA/EIA-568-B.2 specifies cabling components, transmission, system models, and the measurement procedures

TIA/EIA-568-A Commercial Building TelecommunicationsCabling Standard

TIA/EIA-568-B Cabling Standards TIA/EIA-569-A Commercial Building Standard forTelecommunications Pathways and Spaces

TIA/EIA-570-A Residential and Light CommercialTelecommunications Wiring Standard

TIA/EIA-606 Administration Standard for the TelecommunicationsInfrastructure of Commercial Buildings

TIA/EIA-607 Commercial Building Grounding and BondingRequirements for Telecommunications

needed for verification of twisted-pair cabling TIA/EIA 568-B.2.1 is an adden-dum that requirements for Category 6 cabling.TIA/EIA-568-B.3 specifies the component and transmission requirements for an optical fiber cabling system

■ TIA/EIA 569-A is the Commercial Building Standard for Telecommunications Pathways and Spaces The standard specifies design and construction practices within and between buildings that are in support of telecommunications media and equipment

■ TIA/EIA-606-A is the Administration Standard for the Telecommunications Infrastructure of Commercial Buildings, including cable labeling standards The standard specifies that each hardware termination unit must have some kind of unique identifier This standard also outlines the requirements for record keeping and maintaining documentation for administering the network

■ TIA/EIA-607-A is the standard for Commercial Building Grounding and Bonding Requirements for Telecommunications It supports a multivendor, multiproduct environment, as well as the grounding practices for various systems that might be installed on customer premises The standard specifies the exact interface points between the building grounding systems and the telecommunications equipment grounding configuration, and specifies building grounding configurations needed

to support this equipment

European Committee for Electrotechnical Standardization

CENELEC is known in English as the European Committee for Electrotechnical Standardization. It was set up in 1973 as a nonprofit organization under Belgian law CENELEC develops electrotechnical standards for most of Europe; it works with 35,000 technical experts from 19 European countries to publish standards for the European market It has been officially recognized as the European standards organization by the European Commission in Directive 83/189/EEC Many CENELEC cabling standards mirror ISO cabling standards, with minor changes

Although CENELEC and the International Electrotechnical Commission (IEC) operate

at two different levels, their actions have a strong mutual impact because they are the most important standardization bodies in the electrotechnical field in Europe Cooper-ation between CENELEC and the IEC is described in what is known as the Dresden Agreement, approved and signed by both partners in that German city in 1996 This agreement was intended to expedite the publication and common adoption of interna-tional standards and accelerate the standards preparation process in response to market demands This agreement also was intended to ensure rational use of available resources Therefore, full technical consideration of the content of the standard preferably should take place at the international level

NOTE

For more

informa-tion on CENELEC,

visit www.cenelec.org.

International Organization for Standardization

The International Organization for Standardization (ISO) is an international

organiza-tion composed of naorganiza-tional standards bodies from more than 140 countries For example,

the American National Standards Institute (ANSI) is a member of the ISO The ISO is

a nongovernmental organization established to promote the development of

standard-ization and related activities The ISO’s work results in international agreements, which

are published as international standards

The ISO has defined a number of important computer standards, the most significant

of which is perhaps the Open Systems Interconnection (OSI) model, a standardized

architecture for designing networks

U.S Codes

For some networking projects, a permit is required to ensure that the work is being done

properly Contact local zoning departments for information on permit requirements

To obtain copies of local or state building codes, contact the building official for the

local jurisdiction All of the basic building codes—CABO, ICBO, BOCA, SBCCI, ICC,

and so on—that are adopted throughout the United States can be purchased from the

International Conference of Building Officials (ICBO)

It is common for codes requiring local inspection and enforcement to be incorporated

into state or provincial governments, and then possibly down to city and county

enforcement units Building codes, fire codes, and electrical codes are examples Like

occupational safety, these were originally local issues, but disparity of standards and

often lack of enforcement has led to national standards When adopted by state or

local authorities and enforced to appropriate levels, these standards then are turned

over to the lower-level authorities for implementation

Note that violating these codes often can be expensive in both penalties and delayed

project costs

Some codes are enforced variously by city, county, or state agencies This means that a

project within the city would be handled by the appropriate city agencies, while those

outside the city would be covered by county agencies For instance, fire codes can be

enforced by the county building permit department in some communities but by the

local fire department in others

Although local entities inspect and enforce the codes, they often do not write them

Standards-making organizations frequently do that for them For instance, the National

Electrical Code is written to sound like a legal ordinance This makes it possible for

NOTE

For more informa-tion on the ISO, visit www.iso.org/iso/en/ ISOOnline.frontpage.

NOTE

The Americans with Disabilities Act (ADA) has led to several important changes

in new construction, alterations, and renovations regard-ing networkregard-ing and telecommunications Depending on the use

of the facility, these changes might be mandatory, and fines can be assessed for failure to comply.

local governments to adopt the code by vote This might not happen regularly, and the government might fall behind Always know which version of the NEC is in force for your area

Evolution of Standards

As network bandwidth has increased from 10 Mbps to 1000 Mbps and beyond, it has created new demands on cabling Older types of cable are often inadequate for use in the faster modern networks For this reason, the types of cabling used changes over time, and the standards reflect this The following are the standards for TIA/EIA 568-B.2:

■ For twisted-pair cables, only 100-ohm Category 3, 5e, and 6 cables are recognized Category 5 cable no longer is recommended for new installations and has been moved from the body of the standard into an appendix Category 5e or greater is now the recommended cable for 100-ohm twisted-pair cable

■ The Category 6 standard specifies performance parameters that ensure that prod-ucts meeting the standard are component-compliant, backward-compatible, and interoperable between vendors

■ When terminating Category 5e and higher cables, the pairs shall not be untwisted more than 13 mm (0.5 in) from the point of termination The minimum bend radius for UTP horizontal cabling remains four times the cable diameter The minimum bend radius for UTP patch cable is now equal to the cable diameter because it contains stranded wires and thus is more flexible than solid-core copper cables used in horizontal cabling

The acceptable length of patch cords in the telecommunications room has changed from 6m to 5m (19.7 ft to 16.4 ft.) at maximum The acceptable length of a jumper cable in the work area has changed from 3m to 5m (9.8 ft to 16.4 ft.) at maximum The horizontal segment distance remains at 90m (295.3 ft.) If a MUTOA is used, the work-area jumper can be increased in length if the horizontal length is decreased a corresponding amount to keep the total link segment length not longer than 100m (328.1 ft) (see Figure A-15)

The use of a MUTOA or consolidation point also mandates a separation of at least

15 meters (49 ft) between the TR and the MUTOA or consolidation point in order

to limit problems with crosstalk and return loss

NOTE

Most countries have

similar systems of

codes Knowledge

of these local codes

is important if you

are planning to do a

project that crosses

national boundaries.

Figure A-15 Changes to Horizontal Cabling Standards

All patch cords and cross-connect jumpers formerly were required to use stranded cable

to provide the flexibility needed to survive repeated connection and reconnection The

wording around this topic now has been changed from shall to should regarding stranded

conductors This allows solid conductor cord designs

Patch cords are critical elements in the network system Language regarding the onsite

manufacture of patch cords and jumpers still allows these cables to be created, but it

now is strongly encouraged that network designers purchase cables that are premade

and have been tested

Category 6 and Category 7 are the newest copper cables available Because Category 6

cable is used more frequently, it is important for cable installers to understand its benefits

The significant difference between Category 5e and Category 6 is the means used to

maintain the spacing between the pairs inside the cables Some Category 6 cables use a

physical divider down the center of the cable Others have a unique sheath that locks

the pairs into position Still other Category 6 cables use a foil screen that overwraps

the pairs in the cable The latter type of cable often is called screened twisted-pair

cable, or ScTP

To achieve even greater performance than Category 6, Category 7 cables that are

avail-able use a fully shielded construction that limits crosstalk among all pairs Each pair is

enveloped within a foil wrap, and an overall braided sheath surrounds the four

foil-wrapped pairs A drain wire might be provided in future cables to facilitate grounding

Work Area

Field Test Instrument

Begin Permanent Link Optional Transition/Consolidation Point Connector Telecommunications

Outlet/Connector

Telecommunications Room

End Permanent Link

Field Test Instrument Horizontal

Cross-Connect

or Interconnect

Legend

Test Equipment Cord Optional Transition Cabling Cable Between Outlet/Connector or Transition/Consolidation Point Connector and Horizontal Cross-Connect Test Equipment Cord

Maximum Length

G + H 90 m (295 ft)

F G

H I

H

I

Standards for the structured cabling will continue to evolve The focus will be on supporting the new technologies that are converging on the data network, such as the following:

■ IP telephony and wireless utilizing a power signal in the transmission to provide power to the IP phones or access points

■ Storage area networking utilizing 10 GB Ethernet transmission

■ Metro Ethernet “last mile” solutions that require optimizing bandwidth and distance requirements

The standard for Power over Ethernet (PoE) is under development and will be available

in the near future PoE embeds a power signal on cables used for Ethernet transmissions This power signal is used to free IP phones and wireless access points from the need for connection to AC power outlets, simplifying deployment and reducing costs

Safety

Safety is an important concept containing information that often is overlooked in cov-erage of low-voltage telecommunications wiring Students not accustomed to working

in the physical workplace will benefit from labs and training Other important safety topics include these:

■ Safety codes and standards for the United States

■ Safety around electricity

■ Lab and workplace safety practices

■ Personal safety equipment

Safety Codes and Standards for the United States

Most nations have rules designed to protect workers against hazardous conditions

In the United States, the organization charged with worker safety and health is the

Occupational Safety and Health Administration (OSHA) Since the agency was created

in 1971, workplace fatalities have been cut in half and occupational injury and illness rates have declined 40 percent At the same time, U.S employment has nearly doubled from 56 million workers at 3.5 million worksites to 105 million workers at nearly 6.9 million sites

It is OSHA’s responsibility to protect workers by enforcing U.S labor laws Technically, OSHA is not an agency related to building code or building permits However, OSHA inspectors have the power to impose heavy fines and to shut down a job site if they find serious safety violations Anyone who works on or is responsible for a construction

NOTE

For more

informa-tion on OSHA, visit

www.osha.gov

site or business facility needs to be familiar with OSHA regulations The organization

offers safety information, statistics, and publications on its website

MSDS

Amaterial safety data sheet (MSDS) is a document that contains information on the

use, storage, and handling of a hazardous material It provides detailed information on

the potential health effects of exposure and how to work safely with the material It

tells what the hazards of the material are, how to use it safely, what to expect if the

recommendations are not followed, what to do if accidents occur, how to recognize

symptoms of overexposure, and what to do if such incidents occur

Underwriters Laboratories, Inc

Underwriters Laboratories, Inc (UL), is an independent, nonprofit product safety

test-ing and certification organization UL has tested products for public safety for more

than a century The UL focuses on safety standards but has expanded its certification

program to evaluate twisted-pair LAN cables for performance according to IBM and

TIA/EIA (Telecommunications Industry Association/Electronic Industries Alliance)

performance specifications, as well as National Electrical Code (NEC) safety

specifica-tions The UL also established a program to mark shielded and unshielded twisted-pair

LAN cables, which should simplify the complex task of making sure that the materials

used in the installation are up to specification Listing by UL denotes initial testing and

periodic retesting to ensure continuing conformance to standards

The UL tests and evaluates samples of cable and then, after granting a UL listing,

con-ducts follow-up tests and inspections This independent testing and follow-through

make the UL markings valuable symbols to buyers

The UL LAN Certification Program addresses not only safety, but also performance

Companies whose cables earn these UL markings display them on the outer jacket

(Level I, LVL I, or LEV I, for example)

National Electrical Code

The purpose of the National Electrical Code (NEC) is to safeguard persons and

property from hazards arising from the use of electricity This code is sponsored by

theNational Fire Protection Association (NFPA) under the auspices of the American

National Standards Institute (ANSI) The code is revised every three years

Several organizations, including the UL, have established standards for flame and

smoke that apply to network cables laid inside buildings However, the NEC contains

the standards most widely supported by local licensing and inspection officials

NOTE

For more informa-tion on the Under-writers Laboratories, Inc., visit www.ul.com.

NOTE

For more informa-tion on the Nainforma-tional Fire Protection Asso-ciation (NFPA), visit www.nfpa.org/Home/ index.asp.

NEC Type Codes

NEC type codes are listed in catalogs of cables and supplies These codes classify spe-cific categories of products for spespe-cific uses, as shown in Table A-1

Generally, interior network cables are listed in the category of type CM for communi-cations or type MP for multipurpose Some companies choose to run their cables through the testing process as remote-control or power-limited circuit cables CL2 or CL3 (Class 2 or Class 3) general tests instead of through the CM or CP tests, but the flame and smoke criteria is generally the same for all tests The differences between these markings concern the amount of electrical power that could run through the cable in the worst case MP cable is subjected to tests that assume the most power-handling capability, with CM, CL3, and CL2 going through tests with decreasing levels of power handling

Safety Around Electricity

In addition to learning about the industry’s safety organizations, the cable installer should learn about basic safety principles that will be used every day on the job and that are also necessary for the curriculum labs Because many hazards exist when installing cable, the installer should be prepared for all situations so that accidents or injuries can be prevented

Table A-1 NEC Cable Type Codes

low smoke Plenum cable typically is coated with

a special jacket material such as Teflon The letter

P in this code defines a plenum as a channel or

ductwork fabricated for handling air

CMR (communications riser) The letter R shows that the cable has passed

simi-lar but slightly different tests for the spread of flame and production of smoke, compared to CMP cable For example, riser cable is tested for its burning properties in a vertical position Accord-ing to the code, you must use cable rated for riser service when the cable penetrates a floor and a ceiling Riser cables typically have a polyvinyl chloride (PVC) outer jacket

High Voltage

Cable installers work with wiring designed for low-voltage systems The voltage applied

to a data cable would be hardly noticeable to most people However, the voltage of

network devices that data cables plug into can range from 100V to 240V (in North

America) If a circuit failure allowed the voltage to become accessible, it could give the

installer a dangerous shock—and it could be fatal In addition, it is not unheard of for

a low-voltage installer inadvertently to skin the insulation off existing high-voltage

wiring and contact voltage that way

Do not become complacent about the hazards of high-voltage wiring nearby just because

most of the work deals with low-voltage If someone suddenly comes in contact with

high voltage, that person might find it difficult to control his or her muscles or might

not have the ability to pull away

Lightning and High-Voltage Danger

High voltage is not limited to power lines; lightning is another source of high voltage

Because lightning can be fatal and also can damage network equipment, care must be

taken to prevent it from entering the network cabling

The following precautions should be taken to avoid personal injury and damage to

network equipment from lightning and electrical shorts:

■ All outside wiring must be equipped with properly grounded and registered

signal circuit protectors at the point that they enter the building, known as the entrance point These protectors must be installed in compliance with local tele-phone company requirements and applicable codes Teletele-phone wire pairs should not be used without authorization If authorization is obtained, do not remove or modify telephone circuit protectors or grounding wires

■ Never run wiring between structures without proper protection In fact, protection

from lighting effects is probably one of the biggest advantages to using fiber-optics between buildings

■ Avoid wiring in or near damp locations

■ Never install or connect copper wiring during electrical storms Improperly

pro-tected copper wiring can carry a fatal lightning surge for many miles

High-Voltage Safety Test

Voltage is invisible Its effects are seen in tools that run, equipment that operates, or

the unpleasant experience of getting shocked

When working with anything that plugs into the wall for power, it is a safety best prac-tice to check for voltages on surfaces and devices before coming in contact with them Using a known reliable voltage-measurement device such as a multimeter or voltage detector, take measurements immediately before starting work Measure again whenever work is resumed the following day or after a break on any job; someone might have made changes Recheck the measurements again when finished

Some forms of electricity cannot be predicted Lightning and static electricity fall into this category Never install or connect copper wiring during electrical storms; copper wiring can carry a fatal lightning surge for many miles This is particularly an issue with external wiring that is strung between buildings or underground wiring Equip all outside wiring with properly grounded and approved signal circuit protectors These protectors must be installed in compliance with the local codes, which, in most cases, align with national codes

Grounding

Grounding works by providing a direct path to the earth for any voltages that come in contact with it Equipment designers purposely isolate the circuits in equipment from

the chassis—that is, the box where the circuits are mounted Any voltage that leaks

from the equipment to its chassis should not stay in the chassis Grounding equipment conducts any stray voltage to the earth without hurting that equipment Without a proper path to the ground, stray voltages use another path to the ground, such as a person’s body

The grounding electrode is the metal rod that is buried in the ground near the entrance point of the building—that is, the place where electricity enters a building How the ground system connects to the earth is often another matter For years, cold-water pipes, which enter the building from the underground water mains, were considered good grounds Large structural members, such as I-beams and girders, were also acceptable Although these might provide an adequate path to the ground, most local codes now require a dedicated grounding system, such as installed grounding conduc-tors connecting equipment to grounding electrodes

Be aware of the grounding system in the lab and on each job site Verify that the ground-ing system actually works It is not uncommon to find that groundground-ing was improperly done or never was installed in the first place A more common situation occurs when

an installer takes a few shortcuts and accomplishes a technically adequate ground, but

in a nonstandard way Later, changes to other parts of the network or to the building itself might destroy or eliminate the nonstandard ground system, leaving equipment and people at risk