In addition to backing from
Lucent, the LC connector has the
support of Hitachi, IBM
Microelectronics, Kyocera, Methode
Electronics, Molex, MRV
Communications, and Sumitomo
Electric Lightwave.
Lightwave on April 02, 2000
lw.pennwellnet.com
March, 2000
Small-form-factor
revolution pushes
fiber-to-the-x closer
Lawrence Gasman Communications
Industry Researchers
A decade or so ago, fiber-to-the-x
schemes seldom existed outside the
imaginations of futurists and
consultants, except for a few
soon-abandoned incumbent
local-exchange carrier (ILEC) trials.
But after years of unkept promises,
fiber-to-the-x finally appears to be a
technology whose time has come.
Fiber-to-the-curb and
fiber-to-the-cabinet are already
commercial realities.
Fiber-to-the-home (FTTH) and
fiber-to-the-desk (FTTD) are slowly
gaining momentum and may become
mainstream during the next five
years.
What has created this turnaround? In
the past, the justification for
fiber-to-the-x has either been merely
fanciful (three-dimensional
television) or highly specialized
(high-end computer-aided
design/computer-aided
manufacturing). None of these
justifications promised a mass
market. Today, the Internet is the
main reason large numbers of both
residential and business users seek
the high-bandwidth access that fiber
can provide. Moreover, economically,
fiber-to-the-x has become more
feasible, enabled by a slew of new
low-cost components including light
sources, detectors, and, above all,
connectors.
SFF connectors will drive
fiber-to-the-x
The new breed of small-form-factor
(SFF) connectors is revolutionizing
fiber-optic networking, at once
enhancing the economic viability of
fiber-to-the-x schemes and enabling
equipment manufacturers to build
more ports into the same sized box.
It is important to realize, however,
that by helping to create a large and
growing commercial fiber-to-the-x
market, SFF connector vendors are
creating new territory for fiber.
Recent studies on both optical
components and fiber-to-the-x
markets published by
Communications Industry
Researchers (Charlottesville, VA)
reveal some of the key trends in SFF
connectors. The Table summarizes
the major trends.
No single design standard
Unfortunately for users, one trend
that will not occur is the
standardization of SFF connectors
around a single design. (Although
transceiver manufacturers have a
small-form-factor multisource
agreement that specifies a common
footprint for high-density fiber
solutions regardless of connector
type.) Three connector designs-the
LC by Lucent Technologies, the VF-45
by 3M, and the MT-RJ by AMP (now
part of Tyco Electronics) and
others-have such large installed
bases that the disappearance of any
one of these designs appears highly
unlikely.
Click here to enlarge image
Things could have been worse. When
SFF connectors first appeared, there
were five or six competing designs.
(Ed. Note: Other designs currently on
the market include the Opti-Jack
from Panduit Corp., the LX.5 from
ADC Telecommunications, and the
MU developed by NTT of Japan. A
team led by Siecor also has
introduced the SC/QC and SC/DC.)
Although the clout of each of the
three main SFF groups will enable
these camps to shape the market,
the future of this market will
ultimately be determined by the
needs of the service provider and
private networks in which the SFF
connectors are used.
Low loss now an issue
One of these needs is certain to be
good loss characteristics. In past
fiber-to-the-x schemes, this was of
little concern. It was assumed that
"close-in" fiber would carry data at
rates that would not challenge the
loss characteristics of low-end fiber
components. But for
fiber-to-the-cabinet and -desktop
schemes, Gigabit Ethernet, which is
beginning to emerge as the premises
network protocol of choice, requires
low-loss connectorization. (This can
be achieved, for example, by factory
polishing of the plugs and jacks,
which takes the guesswork out of
measuring loss.) Indeed, the
demanding characteristics of Gigabit
Ethernet have challenged one of the
most commonly accepted
assumptions about fiber-to-the-x;
namely, that it will be deployed on a
multimode fiber infrastructure. Now,
fiber-to-the-x on singlemode fiber
may also be required.
Click here to enlarge image
This trend may give something of a
boost to the LC connector. The LC
reflects the demanding requirements
of the public network, where it is the
dominant SFF connector. But from a
marketing perspective, the LC would
have to be repositioned. Today, it is
largely viewed as a costly,
higher-end solution best suited for
longer-haul, singlemode backbone
applications.
In terms of product design, the LC's
rugged low-loss characteristics may
already adapt well to the needs of
the high-end data-communications
segment of the fiber-to-the-x
market. Lucent uses LC connectors in
its structured cabling system. And the
arrival of vertical-cavity
surface-emitting laser (VCSEL)- and
light-emitting diode (LED)-based
light sources that use LCs may
facilitate its use in close-in fiber
markets. In addition to backing from
Lucent, the LC connector has the
support of Hitachi, IBM
Microelectronics, Kyocera, Methode
Electronics, Molex, MRV
Communications, and Sumitomo
Electric Lightwave.
Cost-sensitive market
Given the potential success of the LC
in at least one segment of the
fiber-to-the-x market, Lucent and
other backers of the LC may not
worry too much when LC detractors
criticize the connector as being little
more than an old-fashioned SC
connector in miniature. That said,
there is little doubt that the
fiber-to-the-x market needs
innovative solutions that can either
lower the cost directly or increase
port densities on optical-networking
boxes deployed in that infrastructure.
While the LC is highly robust, it is
perhaps the most conventional
approach to SFF design. The LC is
ferrule-based and uses an insertion/
release mechanism similar to an
ordinary telephone plug. It is also a
single-fiber ferrule. In the most
cost-sensitive sectors of the
fiber-to-the-x market (FTTH and
FTTD), this design may make the LC
less competitive than other connector
approaches that were designed, in
part, to support "close-in" fiber
applications.
In contrast to the LC, the MT-RJ
connector can accommodate two
fibers in one ferrule. According to the
MT-RJ's backers, using the MT-RJ
can save 20% to 30% in connector
costs over single-fiber systems. The
low cost is due in part to the fact that
the MT-RJ does not require fiber
polishing or epoxy gluing, which in
turn reduces the time and skills
needed for installation. MT-RJ
connectors can, it is claimed, be
installed in less than one minute.
3M's VF-45 connector is a ferruleless
interface that reduces cost by sliding
the cable into molded plastic
V-groove clamps rather than using
precision metallic parts. Reportedly,
the VF-45 as a solution is just
one-seventh the cost of traditional
fiber connectors. The VF-45 has
many advantages, but the main one
is that by eliminating precision parts
and connecting the bare fiber in a
V-groove, it offers the lowest cost
potential.
Industry support
MT-RJ technology can be traced back
to a manufacturing method
developed by NTT. However, the
MT-RJ connector did not start
shipping until mid-1998, and it was
not until 1999 that a field-installable
version of the MT-RJ was available.
But despite the relatively recent
emergence of the MT-RJ as a
commercial product, it has a long list
of backers. There are at least 30
companies now using MT-RJ
connectors for their component and
systems-level products. These
include 3Com, Cabletron, Cisco,
Allied Telesyn, Extreme Networks,
Foundry Networks, Fujikura,
Furukawa, Hewlett-Packard, Krone,
Molex, Nortel/Bay Networks, Siecor,
Sumitomo, XLNT, and Xylan.
This list is impressive, especially
since building mindshare among the
component and systems vendors is
currently a strategic priority for the
SFF connector manufacturers. End
users do not appear to perceive
notable differences in quality among
the various SFF connectors. Indeed,
many component and systems
manufacturers use more than one
kind of connector. Therefore,
connector vendors will increasingly
pursue extensive-and
expensive-efforts to educate
customers about the joys of a
particular connector design.
Formal organizations to promote
particular SFF designs already exist.
The VF-45 Action Group, for example,
works to increase mindshare for 3M's
VF-45 product. The VF-45 is part of
3M's Volition cabling system, which
also includes patch panels, cable,
media converters, and even
local-area-network switches. In
addition to 3M, members of this
group include Corning and Siemens
Microelectronics. The MT-RJ Alliance
is another group, which backs AMP's
competing architecture. The goal of
these groups is to champion their
chosen connector design in standards
organizations and industry forums,
through customer seminars and
training, and through the facilitation
of further product design and
development. There is already a
well-developed understanding among
the members of both groups that
educating original equipment
manufacturers and end users about
how these products can facilitate
fiber-to-the-x is the key to success in
that marketplace.
To be effective, such groups must be
forward looking and proactive. These
groups exist to help generate
revenue from emerging
fiber-to-the-x opportunities and to
lay the groundwork for the
next-generation SFF connectors best
suited to these opportunities. In this
context, it is the VF-45/Volition group
that has probably moved the
furthest. While Lucent and the
companies involved in the MT-RJ
program have been pushing their
product as a solution for those who
have already chosen fiber, the
Volition system is specifically
marketed as an offering that proves
that fiber-to-the-cabinet makes good
economic sense.
The Volition approach clearly takes
on copper as a competitor, stressing
the many reasons (higher bandwidth,
greater reliability, immunity from
interference, larger distances
between repeater stations, etc.) for
choosing fiber over copper. All of the
vendors in the SFF space clearly
understand that for the time being,
these products must fit into the
existing copper infrastructure with a
minimal amount of disruption. That
means backward-compatibility to
copper faceplates and connecting
hardware. AMP, for example,
markets a connector that combines
its multifiber ferrule with a traditional
housing that maintains the same
connecting hardware as the existing
copper infrastructure. And while the
backers of the VF-45/Volition solution
unabashedly push fiber as the
primary solution for customers, 3M
still offers a copper solution where
required.
"Close-in" and "very-close-in"
markets
The fiber-to-the-x market can be
segmented in a variety of ways. For
the purposes of the SFF connector
business, it is useful to think of the
market as consisting of two
segments-the "close-in" segment and
the "very-close-in" segment (see
Figure). The close-in segment takes
fiber closer to the user, but it stops
short of going all the way to the desk
or to the home. This close-in market
exists today and consists of
fiber-to-the-cabinet and fiber-to-the
curb schemes.
The very-close-in segment,
consisting of FTTH and FTTD, has yet
to become a reality.
Bandwidth-hungry multimedia
applications already provide an
impetus for bringing fiber all the way
to users, but there is still a lot of
work to be done. Only 3% of fiber
premises networks include FTTD. For
that number to jump significantly, the
industry must work toward providing
an ultra-low-cost and easy-to-install
solution. While there is little doubt
that SFF connectors are changing the
economics of fiber-to-the-x, the full
potential of fiber-to-the-x may not be
realized until a new generation of SFF
connector products appears on the
market.
Lawrence Gasman is president of
Communications Industry
Researchers (Charlottesville, VA).
Magazine
Volume:
17
Issue:
3
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