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Volume 3, Issue 1
October 2006
AN FTTD
POE SOLUTION
Executive Summary
In this issue, we demonstrate that all components are available for FTTD. These components have the following characteristics:
v They enable FTTD at an initial installed
cost equal to or less than that of a traditional horizontal UTP, vertical fiber
network.
v They provide POE at the computer.
v They require no additional power outlets.
v They can be configured to provide back up
power to the POE device, such as a telephone, in the event of a power failure.
v The total package has a small footprint.
In addition, we present methods for handling moves, adds, and changes.
Introduction
During the last four month, I have had more than a dozen conversations and presentations on fiber to the desk (FTTD) and power over Ethernet. As I reviewed the responses to these conversations and presentations, an idea began to form. That idea was the development of a simple device that would enable FTTD and POE. In this issue of The Pearson Perspective, I will share this concept with you.
The Objections/Goals
Some of my presentations and conversations have been to those who wish to reduce their network cost. This reduction can be in both initial installed cost and life cycle cost, as shown at our site www.fttdnow.info. This reduction results from elimination of telecommunication rooms through use of FTTD. Two of the concerns about FTTD have been two requirements: that POE be used and that no additional outlets be required.
A Solution Is Available
The solution is available. To be precise, the components of the solution are available now. They have yet to be put into a single package.
To implement FTTD with POE at the computer, we need a media converter, power for this converter, a POE power transformer, power for this transformer, and a power line liberator. All exist, as separate components.
The media converters have been available for years. They are the size of a deck of cards. I have these converters in my FTTD network. They are IMC MiniMcs with a size of 3.25 inches x 1.75 inches x .75 inches (Figure 1).
Figure 1: Media Converter (Courtesy IMC Networks)
To this, we add a POE power transformer, which are available from multiple sources. One is from D-Link (Figure 2)
Figure 2: D-Link POE Source (Courtesy Cyberguys)
To the combination of these two products, we add a power transformer, such as a wall cube, with which we are all familiar. A refinement of this combination would be incorporation of the power cube inside the case.
At this stage, we need a power cord and an outlet. However, a power supply liberator outlet, such as that in Figure 3, would be plugged into the computer. The computer power cord would plug into the liberator outlet. With this approach, we need no additional power outlet.
Figure 3: Power Cord Liberator (Courtesy Cyberguys)
Of course, the Liberator Cord need not be as large as shown in Figure 3, since the amperage will be reduced. This cord could have adhesive clips to attach it to the computer, to make the entire assembly look professional.
I estimate the size of this unit at about double the size of the IMC media converter, at 3.25inches x 3.5inches x .75inches or 3.25inches x 1.75inches x 1.5inches.[1]
With a Velcro pad to attach to the top or size of the computer and a few additional status lights, we have a media converter/POE power source and power supply at my (estimated) list price of $125-$150. As shown in http://www.fttdnow.info/AN060601.htm, we can justify FTTD for 100BASE-F at $100-$200 per media converter. For GbE, we can justify fiber to the desk at $300-$400 per media converter.
The comparisons referenced in the previous paragraph are based on UTP switches that are not POE. If we eliminate the need for POE switches, we reduce the FTTD network cost by $15- $30 per port, increasing the savings of the FTTD design.
If the computers are on outlets with a back up power source, such as a building UPS or diesel generator, we have a system that will withstand a power outage. If such back up power is not available, we can add a back up battery to power the POE outlet. Such an additional feature would add little to the cost of the unit. Such batteries and circuits exist. They need only be incorporated into a single package.
An Additional Point On MACs
A final concern for FTTD is moves adds and changes (MACs). With an FTTD network, MACs are implemented by installing spare vertical fibers to each floor.
For adds, the manager installs horizontal fiber cables to the new locations. These horizontal cables have factory-installed connectors on the end at the computer and are pulled into location from the computer to the splice enclosure at the vertical riser. This process is not much different from that of UTP networks, except that the fiber adds require no jack installation, whereas UTP adds require installation of two jacks.
These cables are spliced to the vertical cables. The splicing can be performed by an outside service firm. Alternatively, with minimal training, internal personnel with an $1800 tool kit[2] and two mechanical splices[3] can perform the splicing. With training, the splice time can be 5-10 minutes.
For moves, the manager can break the splice at the vertical riser. He can re-splice this vertical fiber pair to newly installed horizontal cable, as indicated above, or to previously installed horizontal cable that was unused.
All changes are implemented at the main cross connect, as all switches are at that location.
Conclusion
Implementation of FTTD with POE can be achieved without the need for additional power outlets. Alternative versions of such a single package can enable back up of the POE device during a power failure. Finally, with planning, MACs can be performed economically and without any significant problems.
Respectfully submitted for your considereation,
Eric R. Pearson, CPC, CFOS
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