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EYE ON FIBER
Justifying Fiber To The Desk
A Decision
Makers Guide
Or
Sifting Reality From Lies, Misconceptions,
Misdirections, and Vested Interests
Many network designers have incurred increased network costs by not accurately and thoroughly evaluating fiber to the desk (FTTD). In this article, I will show the decision maker how to evaluate six factors or arguments that influence the decision to use FTTD instead of the horizontal UTP and vertical fiber network (the traditional network).
First we must clearly identify the basic assumption in an FTTD network: an FTTD network is a fiber link from each PC, etc. to a central facility. All switches and electronics are in one location for the entire building. The only electronics not at this location are the NICs or media converters in or at the PC. This cable system is also called a collapsed backbone or centralized cabling network.
The first argument against FTTD is that FTTD is too expensive or more expensive than a traditional network configuration. This argument is at best a misconception and, in some cases, a lie. For a new network, the argument tends to be false, as demonstrated by the FOLS cost comparison model.[1] Since 2000, this cost comparison model has consistently shown that many FTTD network designs have a initial installed cost lower than that of a traditional network configuration.
The largest factors that influence the cost comparison are port utilization, the real estate cost of the telecommunication room (TR) required on each floor of a multistory office building, and the support costs for those TRs. Note that cost of the optoelectronics is not one of the major factors that strongly influences a decision based on the total installed cost.
Port utilization for an FTTD network is 90 %. Typical port utilization for a traditional network is 70 %. In an FTTD network, you will purchase fewer ports. For this cost factor, an FTTD network has a cost lower than that of a traditional network.
The real estate cost of a TR ranges from $100-$200/ square foot. With the assumption of an 8 ft. x 10 ft. room, the traditional network incurs a cost of $8000-$16,000 per floor, depending on the location of the building. A fully optimized FTTD network does not require these rooms. In a fully optimized FTTD network, you save $8000-$16,000 per floor, or $80,000-$160,000 for a ten story building. THIS IS NOT CHICKEN FEED! In a less-than-fully optimized FTTD network, you save at least $40,000-$80,000.
Support costs for a traditional network configuration include environmental control, surge suppression, access control, UPS, etc. Support costs for a traditional network configuration can range from $5000-$50,000 per room. In an FTTD network, you have no support costs for TRs on each floor, as they are unnecessary. In a ten story FTTD network, you save $50,000- $500,000. THIS IS NOT CHICKEN FEED[2]!
Bottom line: the decision maker should compare the total installed cost of the FTTD network to that of the traditional network. If the decision maker intends to make the decision based on initial installed cost, FTTD may be favored. The FOLS cost model, or an earlier, more detailed model available at no charge from Pearson Technologies, is the best tool to use to make this comparison.[3]
The second argument against FTTD is that the optoelectronics are more expensive than UTP electronics. While this statement is true, it is a misdirection argument that deliberately overlooks the most important cost item: the total initial installed cost. As presented above, the FTTD network does not require significant cost factors. A small portion of the reductions in cost is transferred to the increased cost of optoelectronics.
Bottom line: the decision maker should make the decision based on total installed cost, not on the cost of a single component.
The third argument against FTTD is that fiber switches are more expensive than UTP switches. While this statement is true, it is a misdirection argument that overlooks both the most important cost item, the total initial installed cost, and a reduced cost alternative, the media converter. As presented above, total initial installed cost favors FTTD in some networks.
The reason that some switch manufacturers price their fiber switches higher than their UTP switches is that they do not want you to use fiber switches. If you use fiber switches, you will buy fewer ports than if you buy UTP switches. They price their fiber switches to protect their UTP switch business. The switch manufacturers have a vested interest in selling you as many ports as they can. The switch manufacturers do not benefit from your use of FTTD. Only you benefit from FTTD.
The media converter is a reduced cost alternative to the fiber switch. In all the cost comparisons I have performed, use of an external media converter is less expensive than purchase of a Tier 1 fiber switch. In most cases, the cost of a Tier 1 UTP switch and external media converters has been less expensive than the cost of a Tier 1 fiber switch. In the Pearson Technologies FTTD network, we use media converters.
Bottom line: the decision maker should realize that there are two basic methods to implement FTTD: use of the fiber switch and use of media converters. He should also realize that the switch manufacturers deliberately discourage the use of fiber switches.[4]
The fourth argument against FTTD is that media converters
add an additional point of failure to the network. While this statement, in its
explicit form, is true, the implication that media converter use results in a
reduction of network reliability is not. For example, we have used media
converters for a total of 32 equipment years without failure.[5]
As a second example of high reliability,[6]
Transition Networks publishes the reliability its products at 99.4%. Other
products in the network will tend to fail before the media converters fail.
Bottom line: the decision maker should realize that media converters do not reduce the reliability of a FTTD network by any significant amount.
The fifth argument against FTTD is the need for power for power over Ethernet for VOIP and other network devices. Fiber cables do not carry power. That is a fact. But the implication that one cannot design an FTTD network to provide such power is a lie. Composite cables, those with conductors and fibers in the same jacket, have been available since the mid- 1980s. With such cables, centralized power can be provided to distant sites. In addition, the use of local power supplies will meet the needs of local devices index of refraction
Bottom line: the decision maker should realize that power over Ethernet (POE) can be realized by methods other than a POE switch, while still obtaining the cost savings of an FTTD network.
The sixth and final argument, this time against UTP: no network designer can install UTP without an expectation of replacement in the near future. If the network designer includes the replacement/upgrade cost in the traditional network cost analysis, he will find that FTTD will have a lower life cycle cost than does the traditional network.
Remember the reality of the past 20 years: fiber installed 20 years ago is still being used today, even though the bit rates in networks have increased at least 100 times.[7] In some cases, fiber installed 20 years ago can handle an increase of 1000 times.[8] Why install UTP with an expectation of needed to replace it? Only the UTP proponents benefit from the need to replace UTP. The network designer benefits from the choice of fiber to the desk.
In closing: I do not believe that FTTD will be favored in all situations. If the decision maker looks at real and significant cost factors, he will find that FTTD will be the preferred configuration more often than not.
Respectfully submitted for your consideration,
Eric R. Pearson, CPC, CFOS
President
Pearson Technologies Inc.
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