Tài liệu TRANSITION TO THE NEXT GENERATION docx

Cabling Infrastructure
TRANSITION TO THE NEXT GENERATION
The emergence of 10-Gigabit Ethernet (10-
GigE) began with a surge in demand from data
centers and information-hungry markets, such
as higher education, financial management,
healthcare, engineering design, research and
development, and government institutions.
Today, the acceptance of Gigabit Ethernet mov-
ing to the desktop drives the need for 10-GigE
in the backbone.
While deployment and system upgrades
sound simple enough, careful consideration
should be given to a number of factors when
choosing how and what components should
be used to ensure the infrastructure supports
the protocol today and in the future.
Most campus and building backbones today
are hybrids, meaning they contain both multi-
mode and single-mode fibers within the same
cable sheath. The proportion of multimode to
single-mode will vary depending upon the
organization’s current and future expectations
for distance and bandwidth capacity. Single-
mode fiber is only limited in bandwidth by the
electronics that it connects. Within the typical
LAN, however, most topologies can effectively
be deployed over multimode fiber. For 10-GigE,
attention should be focused on laser-optimized
50/125, which is ideal for 10GBASE-SR, the most
cost-effective derivative of the 10-GigE standard.

Coarse wavelength division multiplexing
(CWDM) will be used extensively in the future
to increase bandwidth. Low water peak single-
mode fiber should be used with CWDM net-
works, as it produces a flattened attenuation
profile and improves transmission. In short,
using the proper multimode and single-mode
fibers effectively ensures that your network will
support the next leap in technology, and pro-
tect the longevity of the cable plant.
Connectivity is the single most overlooked
component of the cabling infrastructure. While
the connector type is not the most critical fac-
tor, the end face preparation of the connector
is crucial for optimizing high-speed systems.
A poorly prepared connector can devastate net-
work performance, resulting in numerous prob-
lems and inadequate data throughput.
A poorly polished connector equates to lost
data, and is an important consideration when
working with multimode assemblies. For this
reason, factory-polished connectors make the
transition to 10-GigE simpler and more reliable.
These preterminated assemblies, or pigtails,
are manufactured in an advanced and dedi-
cated environment where critical end face ge-
ometry measurements can be consistently re-
peated and tested.
When field terminating fiber connections,
connectors should be specified with the

tightest tolerances for better fiber placement
within the ferrule. This will limit insertion
loss and facilitate an easier transition to mul-
tiplexing schemes.
As small form-factor connectors continue to
proliferate, the density of terminations within
fiber panels is effectively doubling. This makes
the difficult and vital task of properly managing
cables and patch cords even more imperative.
This article was provided by Kam Patel, the
director of support technologies for ADC, Eden
Prairie, Minn. He holds a degree in electrical
engineering and has more than 13 years of
experience in the fiber-optic industry.
Regardless of the connector type, the most
important selection criteria for optical mount-
ing and management hardware should be bend
radii and cable slack control for the cables and
patch cords. Throughout the entire channel,
from port to port, appropriate cable manage-
ment should be observed.
The most flexible patch panels are those that
are modular in design, allowing for different
connector types, as well as different fiber types
within the same panel. Consider implementing
patch panels that are sold preloaded with pig-
tails to make the installation faster and more
reliable. Make sure that technicians can easily
access individual connectors to manage cir-
cuits without disrupting adjacent connections.

Choose cable tray systems that protect fiber
integrity and limit bends.
Quality cable trays should be adaptable to
custom requirements, with options for varying
cable density and cable entry and exit points.
In addition, remember such details as compo-
nent placement. For example, fiber patch pan-
els should be placed at the top of the rack with
a minimum of 10 feet of management slack.
Finally, keep in mind that copper cables are
heavier than their fiber counterparts, so,
whenever possible, separating the copper and
fiber cabling is recommended. Although fiber
cables are robust, they are susceptible to
damage if not properly cared for during the
installation process.
For more information from ADC:
www.adc.com
Reprinted from
Communications News
, August 2005
Copyright © 2005 by Nelson Publishing Inc. • www.comnews.comLit.#: 1339339