Raised Floor Patch Panel

Raised Floor Patch Panel
125 Eugene O’Neill Drive
New London, CT 06320
Phone: 860.445.3800
Fax: 888-282-0043
Conserving Valuable Floor Space in
the Data Center
Application of Raised Floor Fiber Patch Panels
John M. Struhar
Director, Fiber Structured Cabling System Solutions
15 June 2005
Copyright © 2005 Ortronics/Legrand, All rights reserved.
Stimulation and Costs Associated with Data Center Growth
Significant legislation, recommendations and financial agreements in the United States and abroad are
dictating how information must be stored, and for how long. For example, the Sarbanes-Oxley Act
requires publicly held companies with a market capitalization greater than $75 million to retain
documents related to financial statements for seven years and effectively requiring the organization’s
top management to sign for the financial accuracy of the company’s annual reports, in essence holding
them accountable for the practices and procedures in their IT departments. The new “Rule 17a” of the
U.S. Securities & Exchange Commission (SEC) establishes strict requirements for brokerages and
exchange members. Under the new rule, a 6 year retention period, has been established for
transactions, e-mails and instant messages. These and many other laws and directives have fueled
the growth of new and existing data centers and storage area networks. Internationally, the European
Union’s “Data Policy Directive” or DPD designates strict privacy requirements for any individuals,
companies or other entities within EU member countries.1
Construction costs for first-class data centers today range from $700-$1,200 per square foot. Typical
annual capacity growth rates in data centers of 50% theoretically would require equally dramatic
increases in floor space requirements. However, new and dense data center processing technologies
such as blade servers have reduced floor space growth requirements to the still considerable range of
30% per year. For a 10,000 ft2 data center, these growth rates translate into spending approximately
$8-12 million for capacity expansion over a three year period.2 Clearly, it is highly desirable to carefully
plan for these capacity increases as well as maximize the utilization of every available square foot of
data center floor space.
The Need for Structure in Data Center/SAN Cabling Systems
Historically, data centers and storage area networks have often been constructed without full
consideration of the implications of frequent capacity expansions and the resultant moves, adds, and
changes that occur over the life of the data center. For example some equipment, such as storage
area networks (SANs), was often installed and cabled by the SAN equipment manufacturer’s
technicians. Other data center equipment, such as processing elements, switches and various
telecommunications systems, might be installed by their respective suppliers’ technicians. While each
of these crews were likely highly competent with their own individual hardware and software systems,
the data center would often contain a mix of disparate technologies and cabling systems without the
manageability critical for rapid maintenance, upgrades and the introduction of new products and
In the early 1980s, when AT&T divested the regional Bell Operating Companies (RBOCs), ownership
of cabling systems within commercial buildings passed from the regional companies to building owners.
A wide variety of proprietary cabling systems and architectures were common at the time and were
addressed by the development of the TIA/EIA-568 “Commercial Building Cabling Standard”. This new
standard introduced the concept of structured cabling systems for these buildings and permanently
changed the way telecommunication and data equipment within buildings is cabled and managed.
“Recent Regulations Affecting IT”, Data Center Management, AFCOM, March/April 2005
Meta Group Study, August 2001
Copyright © 2005 Ortronics/Legrand, All rights reserved.
A New Standard to Simplify the Design & Management of Data Centers
The fiber and copper industries have developed and introduced many new cable and apparatus
technologies and products that offer specific advantages for data center and (SAN) applications. For
the past three years, subject matter experts, many of whom helped develop the TIA/EIA-568 standard
and its successors, TIA/EIA-568-A, TIA/EIA-568-B, and the emerging TIA/EIA-568-C, have been
working to develop a new structured cabling system standard specifically tailored to the requirements of
data centers and SANs. The new standard, TIA-942, “Telecommunications Infrastructure Standard for
Data Centers”3 is expected to benefit data center and SAN design as profoundly as the TIA/EIA-568
series of standards has for commercial buildings. This new data center standard, will finally allow data
center designers to incorporate the appropriate structured cabling systems to efficiently integrate
disparate data center/SAN systems early in the building planning process. The standard views the
data center/SAN as a fully integrated system comprising many components. As a result, it covers
many other interrelated technologies such as network design, location and access as well as
architectural and electrical systems and the crucial element of redundancy.
Conserving Data Center Space with the Raised Floor Fiber Patch Panel
It has been shown that real estate in the data center is costly and, as a result, its maximum utilization is
highly desirable. Managers are faced with the simultaneous objectives of facilitating regular moves,
adds and changes that occur in today’s data centers, while, at the same time, conserving valuable floor
space for other data center equipment that may require continuous access. In an effort to take
advantage of underutilized installation space beneath the raised floor structure, improvised solutions
have often been employed. However, a new fiber apparatus technology, the raised floor patch panel,
has been developed to meet both objectives. Installing this type of apparatus in the floor has the
additional effect of freeing up rack space, an important consideration for many data center designers.
Reclaiming underutilized floor space in the data center is desirable for all media types including UTP
copper, fiber and coaxial cable. While existing copper patch panels readily support requirements for
this media type, they are not well suited to fiber cabling system infrastructures. The many advantages
of fiber, including broad protocol support, smaller diameter, more robust and higher bandwidth cables,
increased security, noise immunity and simplified testing are leading to increased deployment of fiber in
data centers and SANs. The application of raised floor fiber patch panels is not limited to data centers
and SANs, however. Increasing fiber densities in various locations of commercial building cabling
systems as defined in TIA/EIA-568-B may also benefit from the deployment of raised floor patch
Elements of a Well-Designed Raised Floor Patch Panel
Raised floor fiber patch panel systems comprise specially designed patch panels as well as the under
floor plenum-rated enclosures in which they are housed. The enclosure should be designed to
minimize the obstruction of air flow in the plenum airspace and also be sealed to isolate the plenum
environment and prevent creation of a turbulent air flow. The system should be designed to fit neatly
under a 2’ x 2’ floor tile of the type typically used in data centers. An ideal design should reflect careful
attention to the bend radius needs and depth issues associated with popular cassette based systems
such as the Ortronics Momentum® Modular Fiber Optic System4. It should also be able to
Available from Global Engineering Documents, www.global.ihs.com.
Momentum is a registered trademark of Ortronics/Legrand.
Copyright © 2005 Ortronics/Legrand, All rights reserved.
accommodate traditional fiber connectors, whether they are field-terminated, or a component of a preterminated trunk cable assembly. Strain relief, both fore and aft of the patch panel should also be
provided to minimize the potential for optical disconnects and resultant service interruptions. For
maximum flexibility, it should be designed to support both fiber interconnections and cross-connections
as specified in the TIA-942 and TIA/EIA-568-B standards. As cabling densities vary greatly among
data centers, different patch panel rack unit capacities, i.e., 1U and 2U should be supported.
An important, but often overlooked element of a well-managed structured cabling system, whether it be
in the data center or enterprise commercial building is accurate labeling and record keeping. The
newly revised TIA/EIA-606-A “Administration Standard for Commercial Telecommunications
Infrastructure” provides guidelines for documenting and maintaining telecommunications
infrastructures. This new standard offers four levels of scalable administration, based on the size and
scope of the data center structured cabling system. In order to insure complete and accurate records
for equipment that is normally out of sight, the raised floor fiber patch panel system should include a
labeling card for convenient and accurate cabling administration and record keeping, consistent with
Example of Raised Floor Patch Panel System
While there are a variety of plenum-rated under floor enclosures available5, they are quite similar in
design so that a properly designed fiber patch panel can be installed in most of them without
compromising the physical requirements of the fiber cabling system infrastructure. One variation in
existing under floor enclosures is the mounting rail angle in the enclosure to which the fiber patch panel
is attached. The mounting rails and patch panel mounting surfaces should be designed so that the
mounted patch panel is oriented vertically. With this arrangement, the patch cords are horizontal
(parallel to floor tile cover) for best visibility and access. A typical enclosure has mounting rails installed
at an angle of between 45 and 60 degrees with respect to the floor tile cover. However, there are also
enclosures available that have mounting surfaces parallel to the cover’s plane, and the raised floor
patch panel may also be used in this application, albeit without full strain relief.
In order to accommodate mounting angles greater than 45º while still providing the proper fiber
cable/patch cord clearances and bend radius requirements, an auxiliary stand-off mounting bracket
may be utilized to provide an additional 2” of clearance between the fiber patch panel management bar
and the inside of the enclosure. The fiber management bar also provides easy access to the fiber optic
connectors eliminating the need to remove the patch panel. The bracket extends the mounting surface
of the raised floor enclosure to accommodate the depth limitations of 2’ x 2’ enclosures with 56º or 60º
mounting rails.
Figure 1 shows an example of a fiber patch panel designed to meet the above requirements. The
patch panel is designed for installation in common 2’ x 2’ underfloor enclosures. The management bar
maintains proper fiber bend radius requirements. It also provides a convenient point to which cables
can be secured with hook and loop straps. The 1U version includes three 1U openings to
accommodate standard adapter panels or cassettes while the 2U version incorporates six 1U openings
to support additional adapter panels and/or 1U or 2U Momentum cassettes. For maximum flexibility, it
supports both cross-connections and interconnections. Sufficient space is provided for slack storage of
900 µm buffered fiber using management clips attached directly to the floor of the enclosure. Reusable
label cards are provided and hook & loop attachment points are provided to facilitate cable
management within the enclosure. The cards are also easily removable to provide rear patching
American Access Technologies, Inc. is one such provider of these enclosures.
Copyright © 2005 Ortronics/Legrand, All rights reserved.
Figure 1: 1U Raised Floor Fiber Patch Panel Detail (2U Similar)
As indicated above, today’s data centers and high density enterprise structured cabling systems
increasingly deploy optical cassette systems to reduce installation and maintenance time as well as
reduce congestion in crowded racks. With a cassette-based system, a backbone ribbon cable is
terminated with a 12-fiber MTP®/MPO connector.6 The backbone cable is connected to optical
cassettes at each end of the fiber link, with each cassette supporting either one or two MTP/MPO
connectors, for a total of either twelve or twenty-four fibers. Employing factory terminated connectors,
such systems also offer factory-certified performance as the connector installation may be verified
immediately after production with laser interferometry inspection techniques and state of the art
insertion and return loss testing. Figure 2 shows a raised floor patch panel system used with an optical
cassette system.
Figure 2: Raised Floor Patch Panel System for Cassette-based Application
MTP is a registered trademark of US Conec.
Copyright © 2005 Ortronics/Legrand, All rights reserved.
Four cable entry points are provided in the enclosure, allowing for segregation of trunk and equipment
cables. The flexibility of the system also permits it to be readily configured to support either a preterminated or field-terminated system. In a pre-terminated system, a backbone cable with factory
installed connectors extends from the rear of an adapter panel in one rack or enclosure to the mating
end of another adapter panel in another rack. With the raised floor patch panel system, either or both
ends of the pre-terminated trunk cable assembly would be connected to the raised floor patch panel in
the underfloor enclosure. Similarly, if it is determined that field-installed connectors are to be used for
the installation, these connectors would populate the raised floor patch panel in the enclosure.
Raised Floor Patch Panel System Application in the Data Center
The new TIA-942 Telecommunication Infrastructure Standard for Data Centers defines seven “spaces”
and two “cabling subsystems” within the data center. The spaces include the (1) Computer Room, (2)
the Telecommunications Room; (3) the Entrance Room, (4) the Main distribution area (MDA), (5) the
Horizontal Distribution Area (HDA), the Zone Distribution Area (ZDA), and the Equipment Distribution
Area (EDA). The cabling subsystems defined by TIA-942 include the backbone cabling subsystem and
the horizontal cabling subsystem. Figure 3 shows the relationship of the spaces and cabling
subsystems in a typical data center. The first five “spaces” defined in the standard generally involve
many connections and are often best supported with high capacity, high density patch panels and
racks. It is in the ZDA and the EDA that the raised floor patch panel system is optimally deployed. The
equipment distribution area or EDA is the space allocated for end equipment, including computer
systems and telecommunications equipment. Because the EDA is the lowest level of the hierarchical
architecture supported in a data center, there are generally fewer cables connected to this area than to
others. This makes the raised floor patch panel a good fit for this area.
The TIA-942 standard also supports the ZDA which is an optional interconnection point within the
horizontal cabling subsystem. It is located between the HDA and the EDA. ZDAs are particularly
useful in a data center where the need exists for frequent reconfiguration and flexibility. The ZDA is
analogous to a consolidation point (CP) in a traditional commercial building structured cabling system.
Here too, because the expected cable and connection density is often lower at the ZDA than other
areas of the data center, the raised floor patch panel system is often an appropriate choice.
Copyright © 2005 Ortronics/Legrand, All rights reserved.
Figure 3: Example of Data Center Hierarchical Star Data Center Architecture
Clearly there is a need for a systematic and space efficient method of establishing cross-connections
and interconnections at all levels of the hierarchical star or centralized architectures supported in the
data center. Traditional high density, high capacity fiber optic patch panels serve most applications in
the primary “spaces”, i.e., the Entrance room, the Main distribution area, the Telecom room and the
Horizontal distribution area. However, the requirements of less “equipment dense” areas within the
data center such as the Equipment distribution area and the Zone distribution area are also key
elements of the data center structured cabling system. The high cost of data center floor space
requires the most efficient space utilization. The raised floor patch panel meets all of these
requirements providing greater flexibility in structured cabling system design while at the same time
maximizing usage of premium data center floor space.
Copyright © 2005 Ortronics/Legrand, All rights reserved.
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