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Transcript of 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
Communication without boundaries
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
Communication without boundaries
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
Communication without boundaries
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
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Communication without boundaries
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
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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.
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Communication without boundaries
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
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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
Communication without boundaries
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.
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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
Communication without boundaries
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.
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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
Communication without boundaries
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.
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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
Communication without boundaries
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)
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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
Communication without boundaries
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.
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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.
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Communication without boundaries
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
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Terminal, patch panel and hub
Terminal
Moving patch cords
27
Communication without boundaries
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.
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29
Communication without boundaries
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.
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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.
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Communication without boundaries
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.
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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
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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.
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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.
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Communication without boundaries
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.
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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
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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
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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.
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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.
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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)
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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.
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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.
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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.
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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
Communication without boundaries
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
Communication without boundaries
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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