this post has collected questions made by professional during seminars, forum and projects. Solutions are also provided respectively to help readers to form the general understanding of this system.

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Fiberstore (FS.COM) | 10 Frequently Asked Questions About Fiber Optics
Fiber optical technology typically presumes a service life of nearly 30 years. It is not a revolutionary
or a new technology, in fact it is only about carrying light from one point to another. The questions
that frequently asked around the industry are the art of mysticism, thus this post has collected
questions made by professional during seminars, forum and projects. Solutions are also provided
respectively to help readers to form the general understanding of this system.
Do signals really travel faster in fiber optics?
The speed here doesn’t refer to the the speed of signals in fiber optic cable, but the bandwidth
potential of the fiber. Because you know that the speed of light in glass is about 2/3 C, but you
might be surprised to know that signals in UTP (unshielded twisted pair) cables like Cat 5e travel at
about the same speed (2/3 C). Coax, meanwhile, has a faster NVP (nominal velocity of propogation),
about 0.9C, due to it's design.
What do I need for connecting Optic Fiber Cable to a Cat 5 Cable?
You need a media converter available from a number of companies for nearly $100-200.
Do you see any real serious problems in splicing together fiber cables from
different manufacturers, as long as the cable is manufactured to the same
specifications?
No, not as long as they are the same type and size, for example, multimode 62.5/125 or 50/125 and
single mode should be normal (non-dispersion shifted) or dispersion shifted. Some single mode
fibers are made for 1300 nm only, 1550 nm only or both, and they should not be mixed. Note that
there are some other single mode fibers that have special coatings that cannot be mixed with
others. Therefore you are supposed to ask your fiber vendors, splicer supplier or try it first before
going into the field!
Will a single mode connector work on multi-mode cable?
10 Frequently Asked
Questions About
Fiber Optics

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Fiberstore (FS.COM) | 10 Frequently Asked Questions About Fiber Optics
The answer is maybe you can use SM connectors on MM but not the reverse. SM connectors are
made to tighter tolerances—as is SM fiber—so the ferrule hole may be too small for some MM
fibers. MM connectors have bigger holes for the fiber and will have high loss (>1dB) with SM. Also
MM connectors may not be PC (physical contact) polish - terrible for return loss. MM fiber may not
fit the smaller hole in SM connectors.
If you have a 50 micron fiber backbone, can you use 62.5 fiber jumpers on
each end?
NO! On the receiver end it is OK, but on the transmitter end, the larger core of 62.5 into smaller 50
micron fiber will have fiber losses of 2-4 dB.
What is your view on using fiber optic connectors? Is it a better terminating
method than fusion splice?
Of all the SFF (small form factor connectors), LC connector is the one that has become the most
popular. In fact, it is the de facto standard connector for gigabit and 10 gigabit networks. Indeed the
design is very well thought out. The smaller ferrule of a LC to LC fiber cable is easy to polish well and
has excellent mating performance—which leads to low loss and back reflection. It is also easy to
terminante and test.
What is the theoretical lifetime of optical fiber and optical fiber cables?
There is no “theoretical lifetime” of optical fibers. There is no industry accepted “wear out”
mechanism for optical fiber. So there is no physical-chemical reach to test and accelerate in order to
predict an eventual failure mechanism and corresponding failure reaction rate.
Can the same fiber-optic transceivers that are used with Om3 fiber, like SFP+
pluggable modules, be used with Om4 fiber or are there new transceiver types
that need to be used?
Yes, you can use the same fiber optic transceivers for both Om3 and Om4 fibers because the two
fiber types are basically the same except that Om4 fiber has higher bandwidth. The IEEE 10G
Ethernet standard states that 300-meter Om3 and 400-meter Om4 link lengths are supported with
10GBase-S-compliant transceivers.

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Fiberstore (FS.COM) | 10 Frequently Asked Questions About Fiber Optics
Which cabling media are typically used in data center/storage area network
(SAN) environments?
There are a variety of different types of cabling media deployed in the data center. Multimode and
single mode fiber, direct attach connection (DAC) cables, CX4 copper cables, and Category 6A
twisted-pair all have a place.
The cabling type that is deployed is typically based on port type, cost, and distance. Distance is
dictated by the architecture of the data center, which can be centralized/direct connect,
distribution/top-of-rack switching, zoned distribution, or a combination of these.
Fiber is often deployed to connect top-of-rack switches to an aggregation switch at the end of the
row or in another location, in centralized architectures for the "home runs," and in zoned
distribution architectures. Multimode fiber supports all distances in the typical data center, such as
connecting top-of-rack switches within rows back to an aggregation or core layer, or connecting
servers to end-of-row switches. For larger data centers, where MM fiber patch cords may not suffice,
single mode fiber can enable much longer distances. Single mode fiber can also be deployed within
the row as a strategy for future applications that might use multiple-wavelength technologies.
Another alternative to traditional cable and connector deployments for connectivity between
servers and switches within the rack is to use direct attached cables connecting to SFP+ ports.
Is fiber more difficult to install than copper?
It depends on the comfort level and training of the technicians. Because fiber has been accepted as
the standard choice for communications backbones for many years, today's installers are generally
comfortable with the technology, but there is a learning curve for those just starting out. Of course,
the same could be said of new generations of copper cabling. The new generation high-speed
copper cables require more stringent and time-consuming installation techniques than were
required in the past.
Compared to newer grades of copper cable, fewer regulations exist on the methods by which
optical cable is pulled and terminated. In addition, there is no need to worry about the location of
EMI/RFI sources during installation. Also, with fiber cables, there are no requirements for mitigating
techniques when migrating to 10GbE and higher data rates as there are with UTP copper media.

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Fiberstore (FS.COM) | 10 Frequently Asked Questions About Fiber Optics
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Notice: This document is for informational purposes only and does not set forth any warranty, expressed or
implied, concerning any equipment, equipment features, or service offered or to be offered by Fiberstore.
Fiberstore reserves the right to make changes to this document at any time, without notice, and assumes no
responsibility for its use. This information document describes features that may not be currently available.
Contact a Fiberstore sales team for information on feature and product availability.
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