Apac Cable Guide

8/8/2019 Apac Cable Guide

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A g u i d e t o n e t w o r k s

a n d c a b l i n g

S Y S T I M A X S C S

avaya.com

Connectivity Solutions EMEA

E-mail: [email protected]

Web: www.avaya.com

For additional information, please contact your

Avaya Representative

This document is for planning purposes only and

is not intended to modify or supplement any specifications or

warranties relating to Avayas products and services

SYSTIMAX and GigaSPEED are registered

trademarks of Avaya

OptiSPEED and LazrSPEED are trademarks of Avaya

InfiniBand is a trademark of the InfiniBand Association

All names and brands are property of their respective owners

Copyright 2000 Avaya

All rights reserved

Printed in the United Kingdom

EMEA-ms-sm-0030 10/00

Issue 4


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This Guide is for people who need to know about communications cabling as

part of their work, but who are not necessarily specialists in this subject.

Facilities and property managers, architects, design consultants and

departmental heads are among those who now have to consider cabling

issues, and will benefit from the information in these pages.

Cabling for data networks differs significantly from the more familiar power

and telephone networks. An understanding of networks that can carry data

and video, as well as voice transmissions, will help you ensure that cabling

installed today can meet the demands of tomorrow.

The Guide focuses on key strategic and practical factors in planning and

implementing cabling networks in the private or local network. Communications

are rapidly becoming the most important business resource as rapid advances

in computing and telecommunications are altering the way people work, effecting

overall productivity. As this happens, it is vital for organisations to have a

network infrastructure that can turn these developments to their advantage.

The various sections of this Guide give an appreciation of the principles of

cabling and the issues involved. Cross references (in bold) to the Glossary

section enable the reader to deal with the specialist cabling terminology that

is so often a barrier to understanding the subject.

The priority in this publication is to provide information in a form that is easy

to assimilate. It is not an exhaustive study of cabling.

Page

1 The need for networks 2

2 Network strategy 4

3 Alternative network configurations 6

4 Cabling alternatives 11

5 Planning for growth and flexibility 15

6 Avoiding interference 17

7 Standards, categories and regulations 19

8 Network architecture, design

and installation 23

9 Selecting a supplier 29

10 Cost of network ownership 31

11 High-speed networking 33

12 Cabling for the Gigabit Era 35

C a b l i n g f o r t o d a y a n d t o m o r r o w


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1T h e n e e df o r n e t w o r k sG r o w i n g n e e d f o r n e t w o r k s

Dramatic growth in the use of computers has focusedattention on networks and cabling. Where once

telephones were the only concern, managers now have to

deal with the complex and rapidly changing requirements

of computing and information systems.

In the past, it was common for desktop PCs to operate

in isolation. Today, the vast majority of business PCs are

part of Local Area Networks (LANS), enabling them to

work productively together.

LANs can connect PCs to servers and peripherals, or

provide links between transducers, cameras, monitors

and almost any other electronic device. When such links

are made on an ad hoc basis, work areas can soon

become festooned with unidentified cabling, making

fault finding and maintenance near impossible.

N e t w o r k t r e n d s

For organisations that already have sophisticatedcomputer systems, things are also changing. The

move from traditional mainframe and minicomputers to

client/server systems means that proprietary networks

must be replaced by open systems.

Use of networks is also extending to new areas. Many

managers are faced, for the first time, with the need

to develop cabling strategies for networking security

and building management systems, video conferencing,multimedia information systems, and new eBusiness

applications. With the role of networks having

expanded in this way, knowledge of networks has

become essential at all levels of management.

3

Communication without boundaries

Electronic equipment for tasks ranging from computing

and building security to environmental control, can

produce greater benefits as part of integrated systems.

The advantages of individual devices working together

grow as their numbers multiply. At the same time, the

challenges of providing the necessary links also increase.

N e t w o r k b a s i c s

Networks are coherent systems of interconnections

between separate devices that allow sharing of information

and resources such as servers, workstations and peripherals.

A properly designed and implemented network will givethe speed and reliability of communication essential to

an efficient system.

Networks should also conform to accepted national and

international standards, and be able to evolve with a

business changing needs.

Typical network

PC

Hub

Printer


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S p e c i f y i n g a n e t w o r k

Underspecifying networks and cabling is a commonerror. Since the expense and disruption of a premature

replacement is so great, trying too hard to save money

at the installation stage may be unwise.

Some key factors to consider in specifying a network

may be summarised as follows:

Usage patterns, including combined size and

duration of peak loads for all applications

Expected increase in bandwidth demands

The number of users and anticipated changes in

this figure

Location of users and maximum distances between

them

The likely rate of change in users locations (churn)

Connectivity with current and future devices and

software

Space available for cable runs

Total cost of ownership

Regulations and safety requirements

Importance of protection against loss of service and

data theft

5


L o a d e s t i m a t i n g a n d p l a n n i n g

The choice of network and cable types (see sections 4

and 5) depends on the types of devices to be connected,

their location and the way they are used. At the planning

stage, it is important to consider future as well as present

requirements.

Load estimating has become increasingly difficult due to

the bursty and unpredictable nature of bandwidth

requirements associated with current technologies such

as internet access, email (and email attachments),

video and real time streaming media, and file transfers.

T a r g e t l i f e s p a n

The target life cycle of an average cabling installation

is up to 20 years. Over this time, several generations

of networking hardware and software will be installed,

and network throughput requirements will certainly

increase, as may the importance of reliability and security.

2N e t w o r ks t r a t e g y


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7


N e t w o r k t y p e s

There are three main data network topologies in

common use. These are the ring, bus and star types.

Ring networks - Ring networks, as the name suggests,

have a continuous loop that passes every device. This

ensures that signals from one device are seen by allother devices on the ring. In a simple ring, a break in

any part of the network, caused by a fault or system

maintenance activity, will disable the whole system.

More advanced implementations have largely overcome

this problem. The Token Ring LAN is an example of a

ring network.

Bus networks - The bus network connects devices along

the length of a cable, which is, essentially, a high speed

communications link. Devices can be removed from

the bus without disabling the rest of the system. The

Ethernet LAN is an example of a bus network.

Star networks - Star networks incorporate many point

to point links radiating from central equipment. In voice

networks this could be the PABX and in data networks

this could be the mainframe computer or hub. Devices

connected in a star network can be added or removed

easily without disturbing the rest of the network.

3 A l t e r n a t i v e n e t w o r kc o n f i g u r a t i o n sRing network

Bus network

Star network

Hub

Hub

Hub


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Physical topology

A s y n c h r o n o u s T r a n s f e r M o d e ( A T M )

ATM uses fast packet switching techniques to transmitdelay sensitive data, over star networks, at up to 155

Mb/s for twisted pair cabling and up to 2.5 Gb/s over

optical cabling.

F D D I

The Fibre Distributed Data Interface (FDDI) is a high

speed version of the Token Ring, operating over

optical fibres at 100 Mb/s. FDDI systems can have

two complete fibre loops, providing a degree ofredundancy that is useful in critical applications.

P r o p r i e t a r y n e t w o r k s

Proprietary systems are a third common form of

networking. Introduced before standards-based networks

were established, proprietary systems are exclusive to a

particular manufacturer. Among the most numerous are

systems from IBM and Wang, based on star configurations.

These originally used expensive shielded cable of

twin-axial or coaxial types. Now, in many cases, theycan operate over balanced UTP cable with adapters for

balancing, commonly referred to as baluns.

S e r i a l c o m m u n i c a t i o n

Another type of cabling that may be encountered is serial

communications. This is often used to link terminals

and PCs directly to minis, mainframes and peripherals

at relatively low speed. This type of link is not true

networking. However, serial connections can beinterfaced with structured cabling systems and routed

via hubs and backbones. To do this, a passive adaptor

or active interface device is required.

There are two principal forms of serial communications

(asynchronous and synchronous). Both types interconnect

devices via their serial ports.

B a c k b o n e s a n d n e t w o r k l i n k s

Multiple segments of a network, joined by a backbone

cable, can create networks serving large areas, without

excessive cabling. The backbone is a high speed link

that enables separate hubs to work together as a unit. If

a backbone fails, the individual subnets will continue

to operate autonomously.

9


T o p o l o g i e s : l o g i c a l a n d p h y s i c a l

The above descriptions refer to the logical topologies ofnetworks. In practice, however, the physical topology of

all these networks is usually adapted to a star layout

which provides a much more flexible method for moving

users of the network. This is a major advantage when

systems are growing, or there is a significant degree

of churn.

An example of this can be seen in the diagram above.

The system shown has the appearance of a star,but its

logical topology remains a true ring, with the loop

completed within the central hub. Networks based on

star, bus and ring type logical topologies all have their

advocates, and the final choice largely depends on the

application. The star physical topology, however, is

now almost universally accepted within commerceand industry.

E t h e r n e t L A N s

The original Ethernet networks worked over coaxial

cable. The development of 10BASE-T, designed to

operate over balanced UTP cable at data transmission

rates of 10 Mb/s, contributed to the widespread

adoption of Ethernet as the preferred LAN in most

office and industrial applications.

10BASE-T and subsequent (faster) versions of Ethernet

have a star physical topology, with short buses located

in central hubs. As with all LAN systems, PCs and

other active devices connected to 10BASE-T must be

equipped with network interface cards (NICs).

Hub


7/26

11


Backbone cables can be thick coax, thin coax,balanced

UTP (Unshielded Twisted Pair) or optical fibre cable.

Generic cabling standards, however, recommend the

use of multimode fibre or balanced twisted pair

cables in the backbone.

To form large networks, individual LANs of any typecan be linked together via backbone cables, bridges or

routers. With Ethernet, hubs are often grouped in a

single room for security and convenience. In this case,

the backbones are short, and the system is referred to

as a collapsed backbone network.

R e f u r b i s h o r r e p l a c e ?

In many installations, there will be the option to install a

completely new network or refurbish one already inplace. The latter alternative usually offers major

savings, but its viability depends on the existing

cabling and the approach chosen for the new network.

However, ad hoc networks, which use mixed cabling

for historic or cost reasons, have inherent drawbacks.

Todays structured cabling systems are available with

ranges of adaptors for interconnection with all major

hardware types. These will allow established systems,

as well as newer ones, to benefit from the latest cabling

techniques.

Patch panel

Equipment roomMainframe

4C a b l i n ga l t e r n a t i v e sI m p o r t a n c e o f c a b l i n g

Cabling is a key component of any networked system,

so decision makers should be prepared to commit up to

15% of the total cost in this area. Failures in badly

designed and implemented cabling are both common and

expensive, so investment in high quality cabling and

network design is easily justified.

C a b l e c h o i c e

The equipment connected to a network, and the

communications load it imposes, are key factors in cable

choice. There are, however, other considerations:

Maximum distance between network hubs and nodes

Space available in ducting and floor/ceiling cavities

The levels of Electromagnetic Interference (EMI)

present

Likely changes in equipment served by the system

and the way it is used

Level of resilience required

The required life span of the network

Restrictions on cable routing that dictate cable bend

radius

Existing cable installations with potential for reuse


8/26

Building to building backbone

Shielded (STP)

Unshielded twisted pair (UTP)

Foil screened (FTP)

Optical fibre

It is important to note that these maximums apply to

all media. They do not take into account theperformance differences between cable types and

transmission protocols used by the network. In

practice, maximum cable lengths will depend on the

application, the type of network used (eg. 10BASE-T)

and the cables quality. Good cable suppliers and

installers will advise on a cabling systems capabilities

in a particular network.

S i z e r e s t r i c t i o n s

It is important to check the space available for cable runs

before making decisions on cable type. The size, weight

and flexibility of shielded and screened cables

depends on whether foil or braided sleeving is used, and

how many conductors they have. These factors,

together with the shielding/screening material, will

also determine the cables resistance to EMI. It is,

therefore, very important to consider the method of

shielding/screening before choosing such cables.

S h i e l d e d c a b l e s

Shielded cables, referred to as STP, use an expensive and

bulky construction consisting of individually shielded

twisted pairs with an additional overall shield. This is

a robust cable which occupies significantly more space

than unshielded types.

Foil screened cables, usually referred to as FTP, are

constructed of four twisted pairs with an overall foilsleeve. FTP cables can be more compact, but generally

have much lower resistance to EMI than STP types.

Both shielded and screened cables have metal sleeves

that must be grounded well to cancel the effect of EMI

on the signal carried by the conductors, requiring

special grounding and termination considerations.

13


C a b l e a l t e r n a t i v e sTaking the points on the previous page into account, the

first cabling decision is the choice between shielded,

screened, unshielded and optical fibre types, or a

combination of these.

Cables other than optical fibre invariably have copper

conductors insulated and protected by one or more

plastic sleeves. These are often formed into cables

containing anything from two to 1800 pairs. The higher

pair count cables are usually used in the backbone and

especially for voice and low speed data applications.

The maximum lengths over which these cables can run

in backbone and horizontal (hub-to-desk) applications

are specified in the International Standard ISO/IEC

IS11801. These are summarised in the diagram below:

Building 1

Building 2

90m horizontal

500m buildingbackbone

1500m campusbackbone


9/26

Major cable manufacturers specify their products and

warranties assuming a 15 or 20-year life. Over this time,

change is both inevitable and impossible to predict

accurately. The only solution is to specify a network that

is inherently able to accommodate change and growth.

F u t u r e p r o o f i n g

In normal circumstances, a new network should not

become the factor that restricts system upgrades within

the 20-year building refurbishment cycle. Well designed

cabling systems will have the potential to handle data

10-15 times faster than most commonly installed LANs.

This allows new networking technology to be introduced

without replacing the cabling.

The applications it serves define a networks minimum

specification. However, in some situations whereCategory 5 cable is considered adequate it may still

make sense to install better cabling i.e Category 6 to

provide for future needs.

With the shift from proprietary to open computer systems

has come a move from proprietary to generic cabling.

The latter can serve many different types of devices,

ranging from PCs and printers to video cameras and

thermostats.

15


5P l a n n i n g f o rg r o w t h a n d f l e x i b i l i t yU T P C a b l e

Over recent years, advances in UTP cables haveenabled them to carry data at speeds of up to 1 Gb/s.

This allows the use of less expensive and bulky cable in

applications that were previously considered the reserve

of other media types (i.e. coaxial cable, optical fibre).

UTP cables minimise EMIby closely matching each

conductor of a cable pair such that any interference is

cancelled out. This is known as a balanced circuit.

B a l a n c e o f c i r c u i t s

In a perfectly balanced circuit, the sum of noise voltages

induced in the conductors is zero, so there is no

interference with the signal being transmitted. UTP cable

is designed to support cost-effective balanced transmission.

Shielded cable can be less balanced due to the

presence of the shield, thus shield integrity and

grounding are vital. High quality UTP cables achieve a

well-balanced circuit without a need for earthing orshielding the entire circuit.

O p t i c a l a l t e r n a t i v e

For high speed applications in backbone cabling and

over extended distances, optical fibre is the most

commonly used alternative. Optical fibre occupies

little space and is very robust but remains more

expensive to buy than other cable types.

Most optical fibre cable used in LANs is of the multimode

type. Compared to the higher performance singlemode

fibre, multimode allows for the use of less expensive

electronic equipment and is easier (less expensive) to

install and connectorise.

In most networks, optical fibre is used for backbones,

while balanced UTP provides the link to the desktop.

However, as communications speeds increase and

equipment prices drop, networks that take optical

fibre direct to the desktop are going to increase.

Since optical fibre transmits signals via light waves, it is

inherently resistant to all forms of electronic interference.


10/26

Every active electrical and electronic device has potential

to produce electromagnetic flux that can disrupt network

communications. This problem has increased alongside

the growth in the use of electronic equipment.

Both cable selection and cable routing are vital in

safeguarding communications against interference.

In addition to the potential for interference from external

sources, the active pairs in a multi-pair cable can interfere

with each other. This is known as crosstalk.

There are two methods of measuring crosstalk

performance, pair-to-pair and PowerSum. The pair-to-

pair method only measures the maximum interference

caused by any other single active pair in the cable. When

many pairs in a multi-pair cable are active, the loss ofperformance will be greater than that indicated by the

pair-to-pair method.

PowerSum is a more realistic way of measuring crosstalk.

It is based on the measurements taken when all pairs in

a multi-pair cable are active. For cables containing more

than four pairs, PowerSum is the only appropriate method

for testing crosstalk performance.

17


6A v o i d i n gi n t e r f e r e n c eG e n e r i c c a b l i n g

Generic cabling is a major advance, offering users freedomto connect equipment from a variety of suppliers. It also

gives users the potential to employ the same network to

serve several separate systems, for example, telephones,

computers and environmental controls.

F l o o d w i r i n g

The flexibility offered by generic cabling is enhanced

with the use of flood wiring. This is the installation of

sufficient cabling and outlets in a work area to maximise

flexibility of the location for devices connected to the

network. Staff then have similar freedom in how they

arrange their work areas.

S t r u c t u r e o f c a b l i n g

Generic cabling and flood wiring are central elements

in structured cabling, an approach pioneered by the

SYSTIMAX SCS solution from Avaya (the former

Enterprise Networks Group of Lucent Technologies).

This uses an open system approach, supporting allmajor proprietary and non-proprietary standards and

protocols. SYSTIMAX SCS uses balanced UTP and

optical fibre cables deployed in a star topology and

terminated with standard outlets.

Use of simple cable, forming a modular network, makes

it easy to extend or change a system without disrupting

its users. In high growth companies, structured cabling

allows smooth, controlled expansion, with addition ofnew equipment and cable runs at incremental cost.

N e t w o r k c o m p o n e n t s

Patch panels, located in each zone of a building or campus,

allow PCs, peripherals, network hubs and other devices

to be connected and disconnected quickly. In companies

with high rates of churn, this gives considerable savings.

When new cable is laid and outlets added, UTP

structured cabling simplifies the task through its use

of standard components throughout. Flexible small

diameter cabling is also easier to route and takes up

less space than shielded or coaxial types.


11/26

Cabling standards not only encompass communications

performance, they also cover areas ranging from routing

and fire resistance to EMC.

The greatest value of generic standards is in defining

terminology and general approaches. They are not

intended to provide a detailed specification for buildinga network.

I S O a n d E I A / T I A

Both the International Standards Organisation (ISO)

and EIA/TIA have defined generic cabling systems

suitable for medium and large offices. Details of these

can be found in the ISO/IEC IS 11801 standard for

Customer Premises Cabling and EIA/TIA 568B.

ISO/IEC IS11801, EIA/TIA568B and the European version,EN 50173, are all key standards for network installation.

These cover similar areas, but use different approaches

to conformity. ISO/IEC IS11801 is a global standard that

has evolved to meet the needs of all geographic areas.

As a result, some of its requirements are very broad.

19


7S t a n d a r d s , c a t e g o r i e sa n d r e g u l a t i o n sE x t e r n a l n o i s e s o u r c e s

All network components, including connectors and patchpanels must be designed to perform adequately in the

presence of external noise. Particular care is needed

when cabling components are produced by different

manufacturers.

Routing of cable should conform to cable manufacturers'

recommendations and should always avoid potential

sources of interference. Potential sources of EMI are

lift motors, automatic doors and air-conditioning units.

The older this equipment, the more likely it is to produce

EMI. Closed metal conduits and ducting will give

cabling extra protection against sources of EMI that

cannot be remedied or avoided.

Where shielded cable is used, correct termination and

grounding of the shield at connectors is vital. The

potential benefits of the shield must be weighed against

complications related to grounding and safety. Any

lack of shield integrity can render the potential benefitstotally ineffective, and currents may flow in the shield

due to improper grounding .

For most indoor cabling environments, balanced

transmission over UTP offers excellent protection against

external noise. In particularly electromagnetically

hostile or sensitive environments, use of optical fibre

may be the only alternative.

E M C r e g u l a t i o n s

Both the installer and system user are responsible for

ensuring their networked systems have Electromagnetic

Compatibility (EMC) with other electronic devices.

European EMC Directives have been mandatory in all

European Union countries from 1 January 1996, and

penalties against network owners are specified for

non-compliance.

Reputable installers will ensure that cable specifications,routing and ducting are designed to eliminate interference

problems. Some manufacturers also provide warranties

on the EMC performance of certified installations using

their cabling.


12/26

Transmission characteristics of UTP

N e t w o r k s t a n d a r d s

Two major LAN types, Ethernet and Token Ring, are

also defined by standards. The IEEE, the Institute of

Electrical and Electronic Engineers, sets standards for

the implementation ofEthernet

defined through its802.3 committee. Token Ring standards are developed

by the 802.5 committee.

The work of the IEEE committees aims to ensure a high

degree of consistency and interoperability between

systems implemented by different suppliers. Conformance

with their standards is important to network buyers,

since non-standard elements can lead to disruption and

extra cost when networks are modified or extended.

The evolution and widespread acceptance of Ethernet

has ensured that the 802.3 committee continues to be

active, having developed Ethernet specifications up to

1 Gb/s, and currently working on a 10 Gb/s specification

for LAN and WAN.

F i r e p r e v e n t i o n

Standards that are of particular practical interest to

network users are those relating to fire. These differ fromcountry to country, but invariably cover both flame

spread and smoke emission.

21


C a b l e c a t e g o r i e s

EIA/TIA 568B and ISO/IEC IS11801 specify severalcable categories. The first two categories are suited

only to voice and data communications up to 4 Mb/s

and are seldom used in data networking applications.

The characteristics specified for cables in categories 3, 4,

5 as well as the proposed Category 6 (currently in final

stages of standards development) are summarised in the

diagram opposite.

Category 3 cable is generally regarded as suitable only

for networks operating up to 10 Mb/s but can support

networks at 16 Mb/s using active equipment. Its

primary use today is for backbone cabling to support

voice and low speed data applications.

Category 4 cable was developed to support

communications at l6 Mb/s over runs up to 100 metres,

but is now considered obsolete.

Category 5 cabling was designed to support applicationsup to 100 Mb/s. Support for 1 Gb/s requires additional

performance specifications, and existing installations

may not comply.

Category 5e (Enhanced Category 5) is an upgrade to

Category 5 specifications that is targeted at support of

Gigabit Ethernet (1000BASE-T). The maximum

frequency specified for categories 5 and 5e is 100 MHz.

Category 6 cabling was designed with a significant

improvement in bandwidth to support next generation

applications such as low cost Gigabit implementations

(i.e. 1000BASE-TX), and offer maximum future proofing.

The maximum frequency specified is 250 MHz.

Category 7 is also in the process of standardisation.

It is specified to 600 MHz and makes use of bulky

and expensive individually pair shielded cables. The

Category 7 connector is currently not finalised, witha complex switched version of an RJ45 and a non-RJ45

version being considered.

Category 6

Category 5

Category 4

Category 3

Low 100K 1M 250M16M 20M 100M

Frequency (Hz)


13/26

Once network configuration and cabling types are

decided, there remains the practical tasks of designing

and installing the system. The first step, deciding

network architecture, is usually a straightforward task.

Examples of network architecture for typical buildings

and sites are shown in the diagram over the page.

C o l l a p s e d b a c k b o n e s

Variations on the typical architectures are possible. For

instance the backbones may be collapsed so that servers,

hubs and patch panels can be contained within a compact,

secure area. This can save space and improve the systems

physical security.

R e d u n d a n c y

Where systems are mission critical, duplicate backbones

and risers may be needed to implement a mesh designednetwork which will give the required level of system

redundancy. In these situations, duplicate pathways

should be as far from each other as possible.

P h y s i c a l l i m i t a t i o n s

Decisions on the type of cable needed for risers, backbones,

horizontal runs and flood wiring will have been made

at an early stage of planning. At installation, design

and planning stages, it is important to work withinphysical limitations of the chosen cable type.

23


8N e t w o r k a r c h i t e c t u r e ,

d e s i g n a n d i n s t a l l a t i o n

Conforming with a minimum local standard will ensure

that fire officers do not order removal of a network.However, when new cabling is installed there is a strong

case for using cable that conforms to the highest

international standards.

In relation to this impact of a widespread fire, any extra

cost in buying cable to the highest standard is minimal.

Specifying cable with high fire resistance can also reap

immediate benefits in the form of reduced insurance

premiums.

A common approach to minimising the impact of fire

in cabling is to use Low Smoke Zero Halogen (LSZH)

cabling. When this material burns, emission of fumes is

minimised and less smoke will be produced to hinder

evacuation of the building. However, the use of LSZH

materials does not ensure that the cables will have low

flammability. Cables compliant with the IEC 60332

Part 3 specifications offer better fire performance than

the less expensive IEC 60332 Part 1 compliant cables.An alternative is to use plenum, which is a low smoke

and highly fire retardant cable.


14/26

Network architecture

pathways. It is, however, the installers responsibility

to ensure that the requirements of building codes andstandards are met in full.

Alternative methods of cable support and protection

include:

Underfloor ducts

Access (raised) floors

Conduit

Trays and wireways

Ceiling distribution

Perimeter raceways

C o n d u i t s a n d c o n d u i t c e i l i n g d i s t r i b u t i o n

Conduit and ceiling distribution are usually

implemented according to generic standards. EIA/TIA

569, for instance, specifies that conduit sections should

be a maximum of 30m long and have no more than

two 90 degree bends between pull points. Inside bend

radii must be six times conduit diameter, or at least tentimes for conduits over 50mm.

W i r e w a y s

Using suitable equipment and procedures when

installing cable will minimise tension and avoid damage.

Wireway and raceway manufacturers guidelines and code

requirements must also be followed in determining

cable fill for these types of pathway.

C a b l e S u p p o r t

Ceiling distribution, conduits, trays and other pathway

hardware can be used above suspended ceilings.

Alternatively, the cable can be hung loosely using J-hooks,

rings or other means of suspension, at spacings of no

more than 1.5 metres. Unless they are designed for the

purpose, ceiling tiles, rails and supports should not

carry cables. Communication cables should not be

cable tied to power cables for support.

Bundles of over 200 cables may require special attention to

prevent overstressing cables at the bottom of the bundle.

25


C a b l e r o u t i n g

Cable manufacturers will specify minimum bend radiiand maximum pull-through forces. They will also give

advice on proximity to sources of heat, vibration and EMI.

R o u t i n g d i a g r a m

Acomprehensivecable routing diagram must be produced

before installation begins. This will be a guide to installers

and a reference point for future maintenance, expansion

and fault tracing.

C a b l e l a b e l i n g

The diagram should be cross referenced to physical labels

on each cable run. Producing plans and labeling can be

undertaken by the installer or handled by an in-house

systems department. A number of software packages

are available to assist in these tasks.

I n s t a l l a t i o n a n d a c c e s s

Networks should be designed for easy installation and

access, and give cables adequate support and protection.Manufacturers guidelines are designed to ensure that

all these criteria are met. They also take into account

national and international standards applying to cable

Patch panelMainframe

Patch panel


15/26

Terminal, patch panel and hub

Terminal

Moving patch cords

27


OutletPatch panel Hub

Location A

Location B

Patch panel

Location A

Location B

C a b l e t o t h e d e s k

The final leg of a network connection may includecabling that is built into office furniture or partitioning,

or laid under carpets. The consolidation points where

the final cable run joins the permanent building

network are potential weak spots.

Staff and office managers should take special care to

ensure consolidation points are well protected from

impact, crushing and tension loading. The total length

of the building networks horizontal cable and the final

leg to the active device must also be kept within

manufacturers specified limits.

N e t w o r k o u t l e t s

At the end of every network cable is an outlet into

which the cords connected to the devices are plugged.

Outlet locations, quantity and mounting hardware are

important aspects of network design.

CENELEC prEN50174 and EIA/TIA 569 cover many

aspects of outlet location for mounting in walls, floorsand furniture. In addition to standards criteria,

accessibility must be considered.

Administration of cabling in general is covered by

EIA/TIA 606 and ISO/IEC 14763-1.

High quality and good design are of special importance

in outlets and connectors. Over the course of a networkslife, these may be connected and disconnected many

thousands of times, and any weakness will result in a

poor connection. Bad connections and poor connector

performance are, by far, the greatest cause of cable

network faults.

In shielded cable, connections are particularly

important, since any loss of shielding integrity will

have an effect on the cables resistance to EMI. The

quality and location of ground connections require

special attention with shielded cable.

Between the outlets at the periphery of a network and the

hubs at its centre there will invariably be patch panels.

These allow cable runs to be connected and disconnected

very quickly, simply by moving patch cords.


16/26

29


9S e l e c t i n g a

s u p p l i e r

In practice, the most important network decision for most

users is the selection of a supplier. Besides implementing

the network, good suppliers can offer valuable advice

and information.

Since networking is a specialist subject, many

organisations call on suppliers and independent

consultants to help with networking specifications and

strategy. In this situation, it is vital to select a supplier or

consultant with skills and experience that can be trusted.

S y s t e m I n t e g r a t o r s a n d V A R s

Most suppliers describe themselves either as System

Integrators or Value Added Resellers (VARs). The

distinction between these groups, in terms of the services

they supply, is narrowing, although differences in

emphasis remain.

Traditionally, VARs offer hardware, maintenance and

other services in addition to structured cabling to

provide complete networked solutions. They may add

value to the solution through their own hardware

offerings or that of other vendors. Leading VARs

include major computer manufacturers and PTTs.

The System Integrators main area of expertise usuallylies within networking and structured cabling although

they too may offer other services. Awide selection of

System Integrators, from smaller companies offering

bespoke solutions to larger companies offering

additional products and services, is usually available.

P a t c h p a n e l s

In a totally reliable network that never changed, patchpanels would not be necessary. In practice, every

network is subject to change - movement of people or

provision of new services, and it is the patch panel that

allows this to take place quickly with minimum effort

and disruption. Patch panels also make it easier to

detect and bypass network faults.

Patch panels are generally located near network hubs

in a position that minimises the total cabling distance

to outlets.


17/26

Total cost of ownership is a key factor when assessing

bids to supply and install a network. Since a network

can be expected to have a 20 year life, running costs

and the cost of upgrades can equal or exceed the original

capital investment.

N e t w o r k e v o l u t i o n

Adding, removing and changing devices connected to

the network is usually the greatest cost after initial

installation. Structured cabling systems were developed

to reduce this cost, allowing new sections to be added

to a network with minimum effort.

T h e a d h o c a l t e r n a t i v e

The alternative to integrated structured cabling is

ad hoc cabling. This can take various forms, some of

which fall within the definition of structured cabling,but none can be described as integrated. Different types

of cabling components can be linked in ad hoc cabling

to create a system that functions, but may result in high

operating costs and frequent communications problems.

Ad hoc cabling systems usually have a lower initial

cost than fully integrated structured cabling systems

but do not offer the benefits of a guarantee backed by

a single manufacturer. This includes the guarantee ofthe cabling systems EMC performance. It is unlikely

that ad hoc cabling systems will be fully tested to

prove EMC performance and there is then some debate

as to who is responsible for the EMC conformance.

31


10C o s t o f n e t w o r k

o w n e r s h i p

S e l e c t i o n c r i t e r i a

Some of the questions that should be asked of a cablingsupplier are given in the list below.

Size - does the supplier have the resources to handle

the job?

Skill set - does the supplier have all the necessary skills

and have installers received adequate training from the

cabling manufacturer?

Quality - does the supplier have quality processes in place

to cover all aspects of design, materials, installation andtesting, e.g. to ISO 9000 or the TIAs Quality Installation

Company Scheme?

Warranty - does the supplier provide a comprehensive

warranty backed by the cabling system manufacturer?

Does the warranty cover the application that will run

on the network as well as the cabling components, and

include compliance with EMC regulations? Is the warranty

based on fully documented testing by a qualified

organisation?

Materials - will cabling and components be to the highest

standards and produced by a single manufacturer. Are

all the cables and components quality tested and verified

by independent test laboratories with follow-up

verification programmes?

Authorisation - is the supplier fully trained and

authorised by the cabling manufacturer?

S u p p l i e r s

Suppliers authorised by leading cabling manufacturers

are required to meet comprehensive technical and

business standards. They are also provided with full

training in network planning and installation.

Systems installed by authorised suppliers, and

subsequently certified, are usually backed by

manufacturers warranties, ranging from five to 20 years.It is important to note that not all suppliers using cabling

from a particular manufacturer are authorised. Even a

network exclusively using one manufacturers product

will not be guaranteed by the manufacturer unless it is

installed by an authorised supplier.


18/26

P r e p a r i n g f o r t h e f u t u r e

Demand for networking capacity is growing relentlessly.

New communications-dependent systems are being

installed and these are used more intensely than their

predecessors. Even greater communication demands

are created by a new generation of multimedia

applications. These require simultaneous video, voice

and data transmission that can exceed 100 Mb/s for

each workstation. Network technologies and data rates

considered unwarranted only a few years ago must

now be considered a distinct possibility for the future

of any network.

Various LAN and WAN technologies and approaches

have been developed in response to increased demand

for communications and the Ethernet family (which will

soon include specifications spanning from 10 Mb/s to10 Gb/s) has been the most successful technology in the

LAN. The shift to Gigabit networking is already apparent

in backbone implementations, and in the increased

deployment of Storage Area Networks (SANs).

F a s t E t h e r n e t

LANs are rapidly migrating to Fast Ethernet, due to

increased bandwidth demands and reduced prices for

100 Mb/s network equipment and interface cards. Theworldwide acceptance of Category 5 UTP cabling has

facilitated the migration to the 100BASE-TX version

designed for high-performance cabling. Other Fast

Ethernet versions that were targeted to the installed

base at the time (Category 3 cabling) failed to gain

33


11H i g h - s p e e d

n e t w o r k i n g

C o m p a t i b i l i t y

Maintenance costs in ad-hoc cabling systems can behigher, since new components must be obtained from

multiple sources, creating extra overheads. There are

also greater risks of incompatibility as the components

may not have been tested together as a system.

Incompatibility problems may only manifest themselves

when changes are made to the system or higher speed

networks are implemented.

N e t w o r k f a u l t s

Operational faults are potentially an even bigger problem,

and one that is difficult to predict. Fault finding can be

particularly expensive in badly designed and

implemented networks. Full documentation of paths

and easy access to cables and connectors is essential to

minimise the cost of preventative and corrective work.

W a r r a n t i e s

The quality of a networks warranty is the bestassurance that system faults will not result in

unexpected costs. Ideally, the warranty should cover

the full 20-year life expectancy of a cabling system and

include all its components.

To avoid disputes in the event of a claim, the warranty

should cover the cabling components and the LAN

application. Only cabling suppliers that have fully

tested and documented the LAN application on their

systems can offer such a warranty with confidence.

A network designed and implemented by a company

authorised by the manufacturer of all its components

will have fewer areas of doubt in its warranty. In these

situations, there can be no argument as to which

particular supplier is responsible for a fault.


19/26

With no end in sight to the bandwidth explosion, and

given the current growth rates, it can be predicted that

Gigabit LANs will be required by many organisations

within the next 5 years. Gigabit desktop connections and

10 Gigabit backbones are expected to be a requirement

for many organisations by the year 2005. Although the

exact timing of the migration to higher speeds for a

given organisation is not easily predicted, the selection of

a suitable infrastructure today can determine the ability

to react in a speedy and cost-effective manner whenever

the need arises.

In anticipation of future needs, the SYSTIMAX SCS R&D

group of Avaya Labs, building on the heritage of Bell

Labs, has developed leading edge connectivity solutions

to enable the smooth and cost-effective migration to

the high-speed applications of the Gigabit Era.

H o r i z o n t a l c a b l i n g

In the horizontal subsystem, cabling that meets

Category 6 specifications offers inexpensive insurance

against demands up to 1 Gb/s and the ability to

support the more cost-effective and/or higher speed

applications being developed for Category 6 cabling.

The SYSTIMAX GigaSPEED Solution has driven the

standards developments towards Category 6.

35


12C a b l i n g f o r

t h e G i g a b i t E r a

market acceptance as users worldwide realised the

benefits of installing better cabling and the percentageof Category 3 cabling installations decreased rapidly.

S w i t c h e d L A N s

A dramatic increase in network performance can be

achieved by implementing switched LANs, and a

rapid migration to switched LANs has also taken

place. Switching can improve performance between

workstations and servers, but places additional

demand on building backbones.

G i g a b i t E t h e r n e t

The development of Gigabit Ethernet standards for

UTP and fibre media have further established the

dominance of Ethernet in the LAN. Gigabit Ethernet

implementations are already increasing the capacity

of network backbones that aggregate traffic from

multiple 100 Mb/s nodes.

1 0 G i g a b i t E t h e r n e tThe next logical step for network backbones is the

migration to 10 Gigabit Ethernet. The type of optical

fibre selected for the backbone will determine the

type, complexity and cost of the networking equipment

that may be deployed.

S t o r a g e A r e a N e t w o r k s

The data explosion experienced in the LAN has also

resulted in increased requirements for server-to-server

and server-to-storage networks. Data rates beyond 1

Gigabit are common in these networks which may

extend to the building backbone. Commonly deployed

for storage area networks, Fibre Channel technology

operates at various data rates up to 4 Gb/s, and the

InfiniBand architecture currently in development is

being designed for wire speeds of 2.5 Gb/s and beyond.


20/26

The following glossary offers explanations for a number of terms used in this guide. Itadditionally provides explanations for a number of other terms frequently used within thenetworking and cabling industries.

10BASE-T 10 Mb/s Ethemet using 2 pairs of Category 3 cable.

100BASE-T4 100 Mb/s Fast Ethernet using 4-pair Category 3 cable.

100BASE-TX 100 Mb/s Fast Ethernet using 2-pair Category 5 cable.

100VG-AnyLAN 100 Mb/s LAN using Demand Priority Protocol originallydeveloped by Hewlett Packard and AT&T for Category 3 cable.

1000BASE-T 1000 Mb/s (1 Gb/s) Ethernet using 4 pairs of Category 5 cable.

1000BASE-TX A low cost alternative to 1000BASE-T being developed by TIA forCategory 6 cabling.

1000BASE-SX 1000 Mb/s (1 Gb/s) Ethernet operating on multimode fibre with

short wave lasers (850 nm).

1000BASE-LX 1000 Mb/s (1 Gb/s) Ethernet operating on multimode fibre withlong wave lasers (1300 nm).

10 Gigabit The IEEE has initiated work on the specification of 10 Gigabit Ethernet

Ethernet over optical fibre cabling. The standard is planned for completion in 2001or early 2002, with specifications for multimode and singlemode fibre.

Ad hoc cabling Cabling scheme where different types of cabling components from differentvendors are linked together to form a cabling system.

Analogue A method of signal transmission in which the shape of the signal

transmission is a continuously variable and directly measurable physical quantity suchas voltage.

Application A system, with its associated transmission method which is supported bytelecommunications cabling.

Application The uppermost layer (layer 7) of the open systems interconnection (OSI) model.

layer This layer is concerned with support to the user application and isresponsible for managing the communication between applications,

e.g. Email, File transfer, etc.

G1


G l o s s a r y o f

t e r m s

F i b r e t o t h e d e s k

If fibre to the desk is needed, then multimode fibreoffers support for todays applications and future 10

Gigabit requirements. The SYSTIMAX LazrSPEED

Solution has driven the standards developments towards

an enhanced multimode fibre that can support lower

cost 10 Gigabit applications.

B u i l d i n g b a c k b o n e

In the riser backbone, a combination of multimode

and singlemode fibre cables may be required. The

LazrSPEED Solution offers next generation support for10 gigabit technology, virtually eliminating the need for

singlemode fibre in buildings.

C a m p u s b a c k b o n e

Since the campus backbone often provides the most

difficult installation conditions, network planners need

to consider the highest capacity cable plant available.

Singlemode fibre is the recommended media. The

SYSTIMAX OptiSPEED singlemode solutionsprovide a wide range of options for outdoor

environments.

M e d i a r e c o m m e n d a t i o n s

SYSTIMAX SCS media recommendations based on these

developments are summarised in the diagram below.

Riser backbone

Multimode for

10 Gb/sLazrSPEED

Campus backbone

Singlemode for

100+ Gb/s

OptiSPEED

Horizontal

Category 6 for 1+ Gb/s

GigaSPEEDMultimode for 10 Gb/s

LazrSPEED


21/26

Building A facility that provides all necessary mechanical facility and electrical

entrance facility services, that complies with all relevant regulations, for the entry of

telecommunications cables into a building.

BUS Consists of a common transmission path with a number of nodes attachedto it. Sometimes referred to as linear network topology.

Cable fill The ratio of cable installed into a conduit/trunking against the theoreticalmaximum capacity of the conduit/trunking.

Cable routing A detailed drawing showing the layout of the cable routes.

diagram

Cabling A system of telecommunications cables, cords and connecting hardware

that can support the connection of information technology equipment.

Campus A premises containing more than one building adjacent or near to one another.

Campus A cable that connects the campus distributor to the building backbone

backbone distributor(s). Campus backbone cables may also connect building cabling

cabling distributors directly.

Carrier sense Network access method in which nodes contend for the right to send data.

multiple access/ If two or more nodes attempt to transmit at the same time, they abort

collision detect their transmission until a random time period of microseconds

(CSMA/CD) has transpired and then attempt to resend.

Category 3 Industry standard for cable and connecting hardware products withtransmission characteristics specified to 16 MHz, designed to support digital

transmission of 10 Mb/s.

Category 5 Industry standard for cable and connecting hardware products withtransmission characteristics specified to 100 MHz, designed to support

digital transmission of 100 Mb/s.

Category 5e Enhanced Category 5 specifications for cable and connecting hardware

products with transmission characteristics specified to 100 MHz, intendedto support digital transmission of 1000 Mb/s.

Category 6 Industry standard for cable and connecting hardware products withtransmission characteristics specified to 250 MHz, designed to support alower cost implementation of 1000 Mb/s.

Category 7 Industry standard for cable and connecting hardware products withtransmission characteristics specified to 600 MHz, and requiring individually

shielded pair cables. May require a non-RJ45 connector.

Ceiling Distribution system that uses the space between the false or suspended

distribution ceiling and the structural ceiling for housing horizontal cable routes.

Cell relay A fast packet switching technique which uses fixed-length cells.

Generic name for ATM, SMDS and BISDN.

CENELEC European committee for electrotechnical standardisation.

CENELEC EN 50173 The European standard for generic cabling for customer premises.

CENELEC A proposed European cabling systems planning & installation standard

prEN 50174 being developed by CENELEC.

G3


ASCII The American Standard Code for Information Interchange. A widely-used 7

or 8-bit binary code used to represent alphabetic and numeric characters

in computer understandable form.

Asynchronous Two or more signals sourced from independent clocks, therefore havingdifferent frequency and phase relations.

Asynchronous A method of data transfer in which each alphabetic or numeric character

data transfer (represented by 7 or 8 bits) is preceded by start and stop bits todelineate the 7/8 bit pattern from the ideal pattern which otherwise

occupies the (digital) transmission medium.

Asynchronous A high-speed cell-based switching and multiplexing technology based

transfer mode on segmentation of voice, data and video into fixed packets (cells). These

(ATM) cells are transferred along switched paths and are not received on aregular basis (hence the term asynchronous).

Attenuation The effect of signal dwindling, experienced with accumulating line lengthor distance of radio transmission.

Backbone(s) The part of a premises distribution system that includes a main cable routeand facilities for supporting the cable from the equipment room to the upperfloors, or along the same floor to the wiring closets.

Balanced circuit A circuit where equal and opposite signals are generated and sent on totwo conductors. The better the balance of a circuit, the lesser is its

emissions and the greater is its noise immunity (hence the better is itsEMC performance).

Balanced A cable consisting of one or more metallic symmetrical cable elements

twisted (twisted pairs or quads).

pair cable

Balun An adapter used to convert balanced to unbalanced signals in order toconnect legacy equipment or video devices to structured cabling.

Bandwidth The range of frequencies that can be used for transmitting information on achannel. It indicates the transmission-carrying capacity of a channel. Thus,the larger the bandwidth, the greater the amount of information that can

pass through the circuit. Measured in Hertz or bits per second or MHz.km(for fibre).

Basic rate The simplest form of network access available on (BRI) the ISDN (integrated

interface (BRI) services digital network). The BRI comprises 2B + D channels for carriageof signalling and user information.

Bit error rate A measure of quality of a digital transmission line, either quoted as a

(BER) percentage, or more usually as a ratio, typically 1 error in 10E8 or 10E9

bits carried. The lower the number of errors, the better the quality of the line.

Bridge(s) A device used to link two subnetworks using the same communications

method and sometimes the same kind of transmission medium.

Building A cable that connects the building distributor to a floor distributor.

backbone cable Building backbone cables may also connect floor distributors in the same

building.

Building A distributor in which the building backbone cable(s) terminate(s)

distributor and at which connections to the campus backbone cable(s) may be made.


22/26

Distributor The term used for the functions of a collection of components (for example,

patch panels, patch cords) used to connect cables.

EIA/TIA North American Standards organisation.

EIA/TIA 568B North American commercial building telecommunications wiring standard.

EIA/TIA 569A North American commercial building standard for telecommunicationspathways and spaces. Its purpose is to standardise specific design andconstruction practices within and between buildings which are in support

of telecommunications media and equipment.

EIA/TIA 606 North American administration standard for the telecommunications

infrastructure of commercial buildings. Its purpose is to provide guidelines

for a uniform administration scheme for the cabling infrastructure.

Electromagnetic The ability of a system, equipment or device to operate satisfactorily in

compatibility its environment without introducing unacceptable electromagnetic disturbance,

(EMC) or being affected by that environment.

Electromagnetic Electric and magnetic fields (commonly referred to as emissions) generated

flux by equipment or system.

Electromagnetic The interference in signal transmission or reception caused by the

interference (EMI) radiation of electric and magnetic fields.

Equipment cable A cable connecting equipment to a distributor.

Equipment room A room dedicated for housing distributors and application-specific

equipment.

Ethernet A LAN originally developed by DEC, Xerox and Intel. It uses the CSMA/CDprotocol.

Fast Ethernet A 100 Mb/s LAN based on CSMA/CD protocol. See 100BASE-T.

Fibre See Optical Fibre.

Fibre channel This is an ANSI standard describing point to point and switched point to

point physical interface, transmission protocol, signalling protocol, servicesand command set mapping of a high performance serial link for usesbetween mainframe computers and computer peripherals.

Fibre distributed An American National Standards Institute standard for fibre-based

data interface token passing access protocol that operates at a 100 Mb/s data

(FDDI) transfer rate.

Flood wiring The concept of wiring for future growth, by providing full coverage of

information outlets.

Flood distributor The distributor used to connect between the horizontal cable and other

cabling subsystems or equipment (see telecommunications closet).

Foil screened A cable that uses a metallic foil to surround the conductors in a

twisted pair Twisted Pair cable.

cable (FTP)

G5


Channel The end-to-end transmission path connecting any two pieces of application-

specific equipment. Equipment cables and work area cables are included

in the channel.

Churn The relocation of an individual or a group of individuals within a buildingsuch that the workspace or services to the workspace require change.

Client/server A technique by which processing can be distributed between nodesrequesting information (clients) and those maintaining data (servers).

Coaxial Cable A cable with a centre conductor surrounded by a thick insulation,

(COAX) surrounded by an outer conductor made of metal braid. An outer jacketinsulation is optional.

Collapsed This architecture is a backbone topology where wiring concentrators locatedbackbone at floor levels are attached in a star configuration to a central highperformance switching concentrator.

Consolidation An interconnection point in horizontal cabling, typically used to support the

point re-arrangement of furniture cloisters.

Cords A short length of copper wire or fibre optic cable with connectors on eachend. Used to connect equipment to cabling, or to connect cabling segments

(cross-connection).

Cross-connect A facility enabling the termination of cable elements and their connection,

primarily by means of patch cords or jumpers.

Crosstalk An electromagnetic coupling between two physically isolated circuits in a

system. This coupling causes a signal on one circuit to induce a noisevoltage on adjacent circuits, thereby causing signal interference.

CSMA/CD See Carrier Sense Multiple Access/Collision Detect.

Customer Customer owned equipment used to terminate or process information

premises from the public network e.g. Multiplexer or PABX.

equipment (CPE)

Data circuit The equipment terminating and controlling the transmission line, and often

terminating marking the end point of the public data network. Data terminalequipment equipments (DTEs) such as computers are connected directly to DCE.

(DCE)

Data The term used to describe any type of computer or other equipment, when

terminating connected to a data communications network.

equipment (DTE)

Datalink layer Layer 2 of the OSI model. This layer is responsible for error free transmission

of bits on a physical interface. Also known as the link layer. The best knownlayer 2 protocol is HDLC (High Level Data Link Control).

Decibel (dB) A unit used to measure relative increase or decrease in power, voltage orcurrent, using a logarithmic scale.

Digital A technique in which all information is converted into binary digits for

transmission transmission.


23/26

ISO/IEC IS 11801 The international standard for generic cabling for customer premises.

ISO/IEC 14763-1 The international standard for basic administration of generic cabling.

Jumper A cable unit or cable element without connectors used to make a connectionon a cross-connect.

Keying A mechanical feature of a connector system which guarantees correctorientation of a connection or prevents the connection to a jack or opticalfibre adapter of the same type intended for another purpose.

Permanent link The transmission path between two mated interfaces of generic cabling,excluding equipment cables, work area cables and cross-connections.

Local area A LAN allows users to share information and computer resources.network(s) (LANs) Typically, a local area network is limited to a single building.

Multimedia A means of conveying information with components in different media suchas voice, music, text, graphics, image and video.

Multimode fibre Optical fibres that have a large core and that permit nonaxial rays or modesto propagate through the core.

Network Network topology and design.

architecture

Network The piece of equipment that is installed into the expansion port of a personal

interface cards computer and allows communication between the PC and the network.

(NICs)

Network layer The network layer is layer 3 of the OSI model. This layer sets up an end-to-endconnection across a network determining which permutation of individuallinks to be used. Thus the network layer performs overall routing functions.

Node(s) A piece of communications equipment on the network.

Noise The term used for spurious signals produced in a conductor by sourcesother than the transmitter to which it is connected. Noise can affect alegitimate signal to the extent that it is inaccurate or indecipherable when

it reaches the receiver. The higher the speed of data transmission, the worsethe effects of noise become.

Open system A conceptual model specified by CCITT recommendations in the X200 series.

interconnection The model describes the 7-layer process of communication between

(OSI) co-operating computers. The model providesa standard for the development

of communication protocols allowing for computers of different manufacturersto be interconnected.

Optical fibre A transmission medium consisting of a core of glass or plastic surrounded bya protective cladding. Signals are transmitted as l ight pulses, introducedinto the fibre by a light transmitter i.e. Laser or an LED.

Outlets A term used to describe the sockets provided in the work location of astructured cabling system. These are usually 8 pin modular sockets whichcan support a variety of services e.g. voice, video and data.

PABX Private Automatic Branch Exchange. A private switching system thatswitches calls both internally within a building or premises and outside

to the telephone network.

G7


Full duplex Simultaneous two-way communication on the same link or cabling channel.

Full duplex Full duplex Ethernet allows nodes to transmit and receive data at the sameEthernet time, doubling throughput between workstation and switch.

Generic cabling A structured telecommunications cabling system, capable of supporting awide range of applications. Generic cabling can be installed without prior

knowledge of the required applications. Application-specific hardware isnot a part of generic cabling.

Half duplex Two-way transmission on a single link or cabling channel, one direction ata time.

Horizontal cable A cable connecting the floor distributor to the telecommunications outlet(s).

Horizontal runs See horizontal subsystem.

Horizontal The part of the premises distribution system installed on one floor that

subsystem includes the cabling and distribution components connecting the riserbackbone or equipment wiring to the information outlet.

Hub A concentrator or repeater in a star topology at which node connections meet.

Hybrid cable An assembly of two or more different types of cable units, cables orcategories covered by an overall sheath. It may be covered by an overallshield.

IEC 60332 The international standard covering fire performance of cables.

IEEE Institute of Electrical and Electronic Engineers in the USA. This organisationis also involved in producing Local Area Network standards such asEthernet.

Individual pair Where each twisted pair in one overall cable has its own screen.

screened

InfiniBand A high bandwidth switched network topology currently being developed for

architecture Storage Area Networks (SANS).

Integrated Integrated voice and data network based on digital communicationsservices digital technology and standards interfaces.

network (ISDN)

Intelligent Buildings that maximise the efficiency of its occupants and allow

buildings effective management of resources with minimum li fe-time costs

(Source: European Intelligent Building Group).

Interconnect A location at which equipment cables are terminated and interconnected to

the cabling subsystems without using a patch cord or jumper.

Interface cards See Network Interface Cards.

Interference A signal impairment caused by the interaction of another unwanted signal.

ISO International Standards Organisation.

ISO seven layer A 7 layer hierarchical reference structure model developed by the ISO

model for defining, specifying and relating communications protocol.


24/26

Ring A closed loop network topology.

Riser(s) The term used to describe a space utilised by backbone cabling to housecommunications cabling and other building services. This space should

preferably be specified, or allowed for, at the time of the building design.

Router(s) An intermediate system between two or more networks capable of

forwarding data packets at the network layer (layer 3).

Scaleable The ability to adapt to different bit rates.

Screened cable See Foil Screened Twisted Pair Cable.

Serial See Serial Data Transmission.

communications

Serial data Data transmission between computer devices using only a single circuit

transmission path. Whole bytes of information (8 bits) are sent in sequential pattern.Compares with parallel transmission. Parallel transmission is often usedinternally within computing devices because of the higher processing

speeds which are possible, but for long-distance telecommunication, serialtransmission is more economic in terms of line plant.

Serial port(s)/ Normally a DB 9 pin connector located on the mother board of a PC.

transmission A technique in which each Bit of information is sent sequentially on asingle channel.

Server(s) Host Computer(s).

Session layer Layer 5 of the OSI model. Responsible for establishment and control ofdialogues between users on different machines. Synchronisation for reliabledata transfer and token management to control use of the connection areservices provided by this layer.

Shielded twisted An electrically conducting cable comprising one or more elements each of

pair cable (STP) which is individually shielded. There may be an overall shield in which case

the cable is referred to as a shielded twisted pair cable with an overallshield.

Signal to noise The ratio of the signal magnitude to the noise magnitude and is usuallyratio (SNR) expressed in dB. The higher the SNR of a system, the better is its

performance.

Simplex A transmission means allowing only one direction of transmission.(For example public broadcast radio.)

Singlemode Optical fibre with a small core diameter in which only singlemode iscapable of propagation. 8.3 micron is the common standard core size.

Splice A joining of conductors or fibres, generally from separate cables.

Star A physical point to point network topology.

Star physical See Star.

topology

Star quad A cable element which comprises four insulated conductors twistedtogether. Two diametrically facing conductors from a transmission pair.

G9


Packet A type of exchange or network which conveys a string of information

switching from origin to destination by cutting it up into a number of packets and

carrying each independently. A packet-switched effect could be achieved bysending individual pages of a book through the post separately. The

receiving device reassembles the message. Thus a direct connectionbetween origin and destination does not exist at any point.

Patch cord(s) Flexible cable unit or element with connector(s), used to establish connectionson a patch panel.

Patch panel(s) Termination and administration hardware designed to accommodate theuse of patch cords. It facilitates administration for moves and changes.

Pathway(s) Designated cable routes and/or support structures in a false floor or ceiling.

Peripheral(s) Additions to a system, a resource e.g. printer, scanner, etc.

Physical layer Layer 1 of the open systems interconnection (OSI) model. The physical layerprotocol is the hardware and software in the line terminating device whichconverts the databits needed by the datalink layer into the electrical

pulses, modem tones, optical signals or other means which will transmitthe data.

Physical Physical cabling layout i.e. ring, bus, star wired etc.

topology

Ports A computer interface capable of transmitting and or receiving information.

PowerSum A method of testing and measuring crosstalk in multi-pair cables that

accounts for the sum of crosstalk affecting a pair when all other pairs areactive. This is the only method of specifying crosstalk performance that issuited to cables with more than four pairs.

Presentation Layer 6 of the OSI model. Responsible for identifying the syntax of

layer the data being transmitted.

Primary rate The North American 1.544 Mb/s T1 (23B+D) or European 2.048

interface (PRI) Mb/s E1 (30B+D) ISDN interface typically used to connect ISDN PBXs tothe public ISDN.

Proprietary Networks that are not designed or installed to standard based guidelines

networks and do not relate specifically to any relevant standard.

Proprietary Systems that are not Standards specific and therefore are not

systems interoperable with standards based equipment.

Protocol(s) A rule of procedure by which computer devices intercommunicate. Thus aprotocol is the equivalent of a human language, with punctuation and

grammatical rules.

Public network A point of demarcation between public and private network. In many cases

interface the public network interface is the point of connection between the networkproviders facilities and the customer premises cabling.

Raceway Any distribution method designed for holding cables, e.g. conduit, metal or

plastic trunking, cable trays, etc.

Redundancy A fail-safe method of splitting and routing riser/backbone cables via two

risers or more riser cores. Also known as diverse routing.


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Transport layer Layer 4 of the OSI model. The transport layer provides for end-to-end

data relaying service across any type of data network and is responsible

for end-to-end reliability.

Twinaxial cable Twinaxial cable is similar to coax except that the centre of the cable

(TWINAX) contains a twisted pair rather than a single conductor.

Twisted pair(s) A cable element which consists of two insulated conductors twistedtogether in a determined fashion to form a balanced transmission line.

Unshielded An electrically conducting cable comprising one or more pairs none of

twisted pair which is shielded.

cable

UTP See Unshielded twisted pair cable.

Video Real time communications via video between two or more users at

conferencing separate locations.

Wide area Networks that are linked across a large geographical area

networks (WANS) generally using leased lines from a public operator.

Wireless LAN Local area network that communicates using radio technology.

Work area A building space where the occupants interact with telecommunicationsterminal equipment. A users work area which is typically 9 sq. metre or

100 sq. ft.

Work area cable A cable connecting the telecommunications outlet to the terminal equipment.

G11


Star topology See Star.

Storage Area A high speed network or subnetwork of shared storage devices.Network (SAN)

STP See Shielded twisted pair cable.

Structured Flexible cabling scheme which allows rapid reconfiguration for office moves

cabling through patching.

Switching A function carried out by a switching hub, alleviating traffic by makingvirtual connections between transmitting and receiving nodes.

Synchronisation The method by which the bit patterns appearing on digital line systems

may be properly `clocked and interpreted - allowing the beginning ofparticular patterns and frame formats to be correctly identified.

Synchronous Signals that are sourced from the same timing reference and hence areidentical in frequency.

Synchronous Data transfer employing synchronised transmit and receive clocks,

data transfer rather than using start and stop bits to distinguish character patterns fromidle line operation.

SYSTIMAX SCS Brand name of Avayas structured cabling system.

Telecommun- A branch of technology concerned with the transmission, emission

ications and reception of signs, signals, writing, images and sounds; that is,information of any nature by cable, radio, optical or other electromagnetic

systems.

Telecommun- An enclosed space for housing telecommunications equipment, cable

ications closet terminations, and cross-connect cabling. The telecommunications closet is

a recognised cross-connect point between the backbone and horizontalcabling subsystems.

Telecommun- A socket where the horizontal cable terminates. The telecommunications

ications outlet outlet provides the interface to the work area cabling.

Thick coax The transmission medium used for Ethernet or IEEE 802.3 10BASE-2 LANs.It is a 50 ohm thick coax cable (commonly referred to as the thick yellowcable).

Token Ring The transmission medium used for IEEE 802.3 10BASE-2 LANs (sometimesreferred to as CheaperNet). It is a 50 ohm thin coax cable.

Token Ring LAN A 4 or 16 Mb/s LAN standard based on token passing access protocoloriginally developed by IBM. Sometimes referred to as IEEE 802.5 or ISO

8802-5 standard.

Topology The physical or logical configuration of a telecommunications system.

TP-PMD Twisted Pair Physical Medium Dependant. A twisted pair version of the FDDIstandard that allows 100 Mb/s transmission over Category 5 copper cable.

Transducer A sensing device that converts a signal from one form to anothere.g. mechanical to electrical.


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