Most campus and building backbones today are hybrids, meaning they contain both multi- mode and single-mode fibers within the same cable sheath.. Single- mode fiber is only limited in b
Trang 1cabling Infrastructure
_TRANSITION TO THE NEXT GENERATION saps
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 1OGBASE-SR, the most
cost-effective derivative of the 10-GigE standard
Coarse wavelength division multiplexing
(CWDM) will be used extensively in the future
ee
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
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
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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:
ww w.adc.com
Reprinted from Communications News, August 2005