A structured cabling system
(SCS) is a set of cabling and
connectivity products that
integrates the voice, data, video, and
various management systems of a
building (such as safety alarms,
security access, energy systems, etc.)
over a choice of media. This media
could be shielded or unshielded
Twisted pair (STP/UTP) in copper,
single mode (SM) or multi-mode (MM) in fiber cables.
Structured Cabling system is the foundation and the basic
requirement on which all other network equipment
depends.
An SCS consists of an open architecture, standardized
media and layout, standard connection interfaces,
adherence to international standards, and total system
design and installation. Other than the
structured cabling system, voice, data,
video, and building management
systems have nothing in common
except similar transmission
characteristics (analog or digital data
signals) and delivery methods (conduit,
cable tray, raceway, etc.) that support
and protect the cabling investment.
This means that the equipment from
various vendors is connected through a
cabling system that uses common
standards in choice of media,
connectors and topology. The
following are the main standards for Structured Cabling:
ISO/IEC 11801: Standards on Generic Cabling for
Customer Premises
EIA/TIA 568: Commercial Building
Telecommunications Cabling Standard
EIA/TIA 569: Commercial Building Standard for
Telecommunications Pathways and Spaces
TIA/EIA 606: Administration standard for
Telecommunications Infrastructure of Commercial
Buildings (Labeling, Color Coding)
TIA/EIA 607: Commercial Building Grounding and
Bonding requirements for the Telecommunication
Industry.
Today's cabling plant has to support "tomorrow's
requirement". Changes and upgrades have to be easy and
flexible. Often Structured Cabling is neglected but it is
mission critical where change control is a must. Structured
Cabling systems don't break but they often get out of
control because of the negligence. When we look at the IT
Investment, cabling will be around 5 per cent and we
expect it to last for the next 15 to 20 years and support all
the future applications.
Since applications are dependent on the quality of the
network, one recommends the deployment of Structured
Cabling as a system that is procured from a leader in the
industry with vast experience in the connector and cable
market with reliable and good quality products. Deployed
as an end-to-end solution, it should ensure consistency in
performance and delivery of bandwidth to meet
tomorrows convergence networks requirements. While
working with a network installer one must ensure that he
is vendor certified/trained engineer and offers an effective
network solution that is easy to implement and support.
While many vendors offer a variety of warranties today,
ensure that your network is not just certified for
components but also for performance.
TYPES OF CABLES
Optical Fiber: An important characteristic of fiber optics
is refraction. Refraction is the characteristic of a material to
either pass or reflect light. When light passes through a
medium, it "bends" as it passes from one
medium to the other. Fiber-Optics use
light pulses to transmit information
down the fiber and the light pulses move
easily down the fiber-optic line because
of a principle known as total internal
reflection. "This principle of total
internal reflection states that when the
angle of incidence exceeds a critical
value, light cannot get out of the glass;
instead, the light bounces back in "
When this principle is applied to the
construction of the fiber-optic strand, it
is possible to transmit information
down fiber lines in the form of light pulses.
There are generally five elements that make up the
construction of a fiber-optic strand, or cable: the optic core,
optic cladding, a buffer material, a strength material and
the outer jacket. The optic core is the light carrying
element at the center of the optical fiber. It is commonly
made from a combination of silica and Germania.
Surrounding the core is the optic cladding made of pure
silica. It is this combination that makes the principle of
total internal reflection possible. The difference in
materials used in the making of the core and the cladding
creates an extremely reflective surface at the point in
which they interface. Light pulses entering the fiber core
reflect off the core/cladding interface and thus remain
within the core as they move down the line.
Single Mode: Single-mode cable accepts only one mode
of light - the axial mode and supports best at 1310 and 1500
nanometer wavelength. The single-mode cables are the
most important cables for long-haul use (carrier and
Internet core). The cable has a small core (8 to 10 microns)
that forces the light to follow a more linear single path
down the cable, as opposed to the multipath reflections of multimode cable. This cable has
the highest bandwidths and
distance ratings.
The core diameter for single-mode
cable is typically 8 to 10 microns with a
cladding diameter of 125 microns.
Multimode: Multimode cable accepts
many modes of light and supports best at 850
and 1300 nanometer wavelength. This cable has a
relatively large diameter core (50 to 100 microns) and a
total diameter of 125 microns. Step-index multimode cable
has an abrupt change between core and cladding while
graded-index multimode cables have a gradual change
between core and cladding. For example, the minimum
recommended cable type for FDDI (Fiber Distributed Data
Interface) is 62.5/125-micron multimode fiber-optic cable.
That means the core is 62.5 microns and the core with
surrounding cladding is a total of 125 microns.
The core specifications for step-index and graded-index
multimode cables are typically 50 and 62.5, where as the
cladding diameter for step-mode cable is 125 microns.
Within multimode there are four varieties (OM1, OM2,
OM3 and OM4), which is the most popular in the
enterprise Networks, an OM1 (62.5 micron), OM2 (50
micron) fibers are becoming obsolete in the industry
because of the large bandwidth requirements, where its
replaced with OM3 and OM4 (50 micron Lazer Optimized
Fibers) which could support high Effective Modal
Bandwidth of 2000 and 4700 MHz-km respectively and
these fibers would also support for the upcoming
40/100G requirements. But this fix still has distance
limitations.
Twisted Pair: Twisted pair cable consists of a
pair of insulated wires twisted together. It is a
cable type used for telecommunication purpose.
Cable twisting helps to reduce noise pickup from outside
sources and crosstalk on multi-pair cables.
Twisted pair cable is good for transferring balanced
differential signals. The advantages of improved signal-tonoise
ratio, crosstalk, and ground bounce that balanced
signal transmission bring in wide bandwidth. By
transmitting signals along with a 180 degree out-of-phase
complement, emissions and ground currents are
theoretically canceled. This eases the requirements on the
ground and shield compared to single ended transmission
and results in improved EMI performance.
Shielded TP: Cables with a shield are called shielded
twisted pair and have copper media, commonly
abbreviated STP. The degree of reduction in noise
interference is determined specifically by the number of
turns per foot. Increasing the number of turns per foot
reduces the noise interference. To further improve noise rejection, a foil or wire braid "shield" is woven around the
twisted pairs. This shield can be woven around individual
pairs or around a multi-pair conductor (several pairs).
Unshielded TP: Cables without a shield are called
Unshielded twisted pair and is the Copper media, which is
being used for increasingly higher data rates, and is the de
facto standard for horizontal wiring. UTP is a very flexible,
low cost media, and can be used for either voice or data
communications. Its greatest disadvantage is the limited
bandwidth, which restricts long distance transmission
with low error rates.
A Twisted Pair is a pair of copper wires, twisted together
and wrapped with a plastic coating. The twisting increases
the electrical noise immunity, and reduces the bit error rate
(BER) of the data transmission.
Intelligent Cabling Systems: Intelligent cabling
system is a solution which will provide complete up to date
accurate documentation in real-time by which enabling
customers to minimize costly network failures and
downtimes, integrates network layer and physical layer
management, features integration into facility
management tools, reduce staff workload, and more
importantly reduce the time for moves, adds and changes
by automating the management of the physical layer.
The benefits from intelligent cabling systems are:
- Minimize the Network down time
- By improving the process of moves, adds and changes,
reduces the cost associated.
- Guarantees the documentation accuracy
- Improves the response time
- Online tool for troubleshooting
- Mobility - Remote working over the internet
- Improves the performance and Service levels
- Remote management
- Asset Utilization
- Security - Identify unauthorized changes and immediate
notification of alarms
(Mylaraiah J.N. is Country Technical & Marketing
Manager at TE Connectivity, erstwhile, Tyco Electronics Corp
(India) Pvt Ltd)