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EYE
ON FIBER
3
BLACK LIES, 3 WHITE LIES AND 1 STATISTICAL LIE ABOUT FIBER TO THE DESK NETWORKS
Executive Summary
This application note provides the network planner with realistic information concerning fiber to the desk (FTTD). With this information, the network planner can: 1) made rational decisions concerning network design and 2) reduce his network cost through FTTD.
Introduction
The
savvy network manager will implement new or retrofit data networks in the most
cost effective manner possible. Usually, cost effective means lowest initial
installed cost. Alternatively, cost effective means lowest life cycle cost. In
many situations, fiber to the desk (FTTD) has both lowest costs.
Unfortunately,
a number of myths and misconceptions about fiber exist. Belief in these myths
prevents planners from benefiting from fiber to the desk. In this application
note, we present the realities of fiber to the desk. We label these myths and
misconceptions: black lies, when they are blatantly untrue; white lies, when
they may be true but irrelevant to making an intelligent and practical
decision; and statistical lies, when they can be true but are not true most of
the time.
Black Lie #1: Fiber Networks Are Too Expensive
This
black lie is that optical fiber networks are too expensive to justify. This lie
is a black lie because the truth is the opposite.
The Reality
When the fiber
network is properly configured and a total initial installed cost or a life
cycle cost analysis is performed, the initial installed cost or life cycle cost
favors FTTD in most medium and large corporate networks.
The reason for
this reality is that there are at least two cost factors that are higher in UTP
networks than in fiber networks. The UTP proponents will not mention these two
factors.
These two factors,
by themselves, can cause the initial installed cost of a fiber to the desk
network to be less than that of a traditional UTP network. If a fiber to the
desk (FTTD) network has the lowest initial installed cost, it will,
automatically have the lowest life cycle cost.[1]
White Lie #1: Fiber Cable Is More Expensive
This lie is a white lie in that it
can be true, may not be true, and is irrelevant and misleading. In the past and
the present, fiber cables have been or are more expensive than UTP. However,
some fiber cables are less expensive. For example, the FOLS issued a cost
comparison of $0.30/foot for UTP and $0.24/foot for fiber cable.
The Reality
Regardless of the
cable cost comparison, the cost of the cable is irrelevant and the comparison
is misleading. The total installed cost or the life cycle cost comparison is
being used to make a rational and realistic comparison. When the decision maker
or network planner calculates either of these two costs, the comparison can,
and often does, show the fiber to the desk network to be lower in cost than the
UTP network.
White Lie #2: Fiber Is Fragile
This lie is a white lie for three
reasons:
ü Because it is true but irrelevant
ü Because it is not a fair comparison and
ü Because
it is misleading.
The Reality
This white lie is
irrelevant. It is true that fiber can be fragile, but only when the primary
coating is removed. However, you never use fiber in a network. Instead, you use
a fiber cable.
To be a fair
comparison, you would have to compare fiber to the conductor in the UTP cable.
But you never use a conductor. Instead you use a UTP cable.
When you compare
cables, fiber cable is stronger than UTP cable: fiber cable has a typical
maximum pulling load of over 100 pounds-force while UTP is limited to 25
pounds-force.[2] The reality is that fiber cable will
withstand loads higher than those that UTP will withstand.
Statistical Lie #1: Fiber Networks Are More Expensive
This is a statistical lie, in that it can be true. A few corporate network configurations are more expensive with FTTD than with UTP. However, when you consider all costs of both types of networks, most corporate networks will have a lower initial installed cost with FTTD than with UTP.
The Reality
There are three
cost factors in a UTP network that are higher than in a FTTD network: TR real
estate cost, TR support cost and real switch cost per port. As detailed
elsewhere, the real estate and support costs can be $400-$1000 per node higher
in a UTP network than in a FTTD network. The real cost per switch node can be
31.74 % higher in a UTP network higher than in a FTTD network. In a FTTD
network, the reduction in these costs can be more than the increased cost of
fiber optic media converters. Thus, FTTD network costs less than the UTP
network.
Some switch
manufacturers do not want you to use FTTD. Doing so will reduce the number of
ports you need. If you design a FTTD network, you will need 31.74 % fewer ports
than you would need with a UTP network. These manufacturers price their fiber
switches high enough to force your decision back to UTP. They benefit but you
lose..
However, if you
use media converters, you will find that the initial installed cost of a FTTD
network is less than that of a UTP network. The media converter manufacturers
have the same interest you have: reduce the network cost. Their products are
priced to allow you to reduce network cost by using FTTD.
Pearson
Technologies has developed a detailed cost comparison model. Without trying to
bias the numbers against UTP, all 12 of the comparisons show FTTD networks are
lower in cost than UTP networks. This result is significant because the model
has a slightly bias against FTTD! We expect real comparisons to favor FTTD more
than the model indicates.
White Lie #3: Media Converters Are An Additional Point Of Failure
This is a white lie because it is technically true, but irrelevant.
The Reality
As you increase
the number of components in any system, the probability of failure increases.
Thus, this lie is technically true. But media converter manufacturers offer
lifetime or 5 year warranties for their products. Thus, this lie is irrelevant.
Pearson Technologies Inc. has had its FTTD network in operation for 3.5 years
without a single failure or other problem with its media converters. In the mid
1990s, BellSouth personnel reported that its data network operated for 5 years
without any failures.
Black Lie #2: Fiber And POE
This white lie is that use of FTTD does not let you implement POE. This lie is a white lie in that you can deliver power to any location.
The Reality
This lie is
misleading because very few networks need POE to all locations. Installing POE
in all cables drives up the cost per port by $10-$15/port. This increase in
cost results in FTTD saving the planner more than a network without POE.
For example, you
can transmit power
over the fiber . In addition, you can transmit power to the necessary
location without UTP-you can use existing phone cable. Or you can install fiber
optic cables with a twisted pair to carry the power.
Black Lie #3: Fiber And VOIP
The lie is that you cannot implement VOIP in a FTTD network. The opposite is true.
The Reality
3Com offers four port switches with a integral fiber converter. With this product, you can run VOIP and data from a desktop in a FTTD network.
Respectfully submitted for your consideration,
Eric R. Pearson, CPC, CFOS
President
Pearson Technologies Inc.
For Mr. Pearson contact information, click here.
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