R&M Data Center Handbook

www.datacenter.rdm.com
R&M’s visual and mechanical coding system and locking solution together provide an enormous improvement to
passive data center security.
Security solutions from
R&M, ranging from
insertable color coding
units (left) to locks on
patch cords (right)
3.9.4 Glass Fiber Cables (Fiber optic)
Glass fiber is a fascinating medium. It promises bandwidth that is virtually without limits. However, it is also a delicate,
brittle medium. It takes a skilled person to handle glass fiber cabling. Nevertheless, by using proper planning
and well-thought-out product selection, data centers can get a successful and problem-free start into their glass
fiber future. The continuously growing requirements of data centers leave no other choice. Nowadays, data
centers must include glass fibers in their planning to enable them to cope with migrating the data center to 40/100
gigabit Ethernet, growing data volume and many other requirements beyond that.
Scalability, performance, access time, security, flexibility, and
so on can be optimized through the use of glass fibers. Advances
in glass fiber technology, practical knowledge from
manufacturers and revolutionary standards help users to make
the right decisions during the planning process and to invest in
a future-proof installation. An overview appears below of the
fundamental topics, terminologies and issues that play a role in
making plans for a glass fiber cabling system in a data center.
We then present an orientation for decision makers, and information
on some progressive glass fiber solutions that are
currently available on the market.
3.9.5 Multimode, OM3/4
Optical fibers can be differentiated between glass optical media (Glass Optical Fiber, GOF) and plastic (Plastic
Optical Fiber, POF). Due to its clearly lower performance capabilities, POF is not suitable for data center applications.
One can differentiate between three types of glass fibers:
• Multimode glass fibers with step index profile
• Multimode glass fibers with gradient index profile
• Single mode glass fibers
Multimode and single mode specify whether
the glass fiber is designed for multiple
modes, or only for one mode. By means of
a “smooth” transition between the high and
low refractive index of the medium, the modes
in multimode glass fibers with a gradient
Core glass (10, 50, 62.5 µm)
Cladding glass (125 µm)
index profile, in contrast to those with a step
index profile, no longer run straight, but in a
Primary coating (0.2 ... 0.3 mm) wave shape around the fiber axis, which
evens out modal delays (minimization of
Secondary coating (0.6 ... 0.9 mm)
modal dispersion). Because of its good costbenefit
ratio (production expense to band-
Structure of a glass fiber (core: 10 µm single mode, 50 & 62.5 µm multimode)
width length product) this glass fiber type
has virtually established itself as the standard fiber for high-speed connections over short to medium distances,
e.g. in LANs and in data centers. Apart from attenuation in db/km, the bandwidth length product (BLP) is the most
important performance indicator for glass fibers. BFP is specified in MHz*km:
a BLP of 1000 MHz*km means that the usable bandwidth comes to 1000 MHz over 1000 m or 2000 MHz over 500 m.
Page 116 of 156 © 08/2011 Reichle & De-Massari AG R&M Data Center Handbook V2.0