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Is An All-Fiber LAN
Really Cheaper Than Copper?


The answer, surprisingly, may be "yes" for new construction and major renovations. I know, "everybody knows fiber is too expensive," but that turns out to be a generalization that is out of date and comes from a "apples-to-oranges" comparison that favors the traditional copper architecture.

This copper LAN layout as described in the EIA/TIA 568 standard (shown on the left of the drawing), follows traditional telephone system designs from decades ago. It divides the LAN into "horizontal" cabling no longer than 90 meters connecting the desktop and a hub in a wiring closet. The horizontal distance limitation is the performance of the UTP cables. Every closet has a hub, which requires space, power, UPS and installation. Maybe even AC! Most closets have punchdowns, patchpanels and other passive hardware too.

The "horizontal" cabling connects to a "backbone," which by virtue of bandwidth and distance requirements, is mostly fiber optics already. The backbone connects all the hubs to a central communications facility, usually called a main telecom closet, where the complete LAN is managed.

When the "copperheads" (I refuse to divulge the source of that term!) compare fiber-to-the-desk (FTTD) to copper, they show that a horizontal fiber cable plant may only be a few dollars more than Cat 5 UTP, but the network electronics for horizontal fiber cost a lot more, making fiber uneconomical.

That is a totally erroneous comparison, because with fiber you aren't limited to 90 meters. With fiber, you don't need horizontal and backbone links, you don't even need a telecom closet! You just need one link, a pair of fibers straight from the desktop to the main telecom closet (shown on the right of our drawing) You don't need a hub, power and backup power for the hub, racks and space for all that or installation and maintenance labor. At most, with fiber you have an intermediate passive patch panel to connect desktop cables to the backbone cable and some extra (cheap!) fibers in the backbone cables.

So how much extra does the copper network cost? Different installations will yield different numbers, but in realistic comparisons, an all-fiber network usually comes out equal or cheaper!

Sound too good to be true? One of the most sophisticated LAN installations anywhere, the Getty Museum in Los Angeles, saved almost $4,000,000 by going to an all-fiber network. That's correct - FOUR MILLION DOLLARS! According to a Corning presentation at a recent 3M seminar, with UTP, they would have had to build 55 telecom closets in the museum, with hubs, power, etc. at a cost of $73,000 per closet. With an all-fiber network, they needed only one closet, saving an incredible amount of money (not to mention floor space for artwork, researchers, etc.)

Another big issue in LANs is reliability. We all know about fiber's immunity to electrical noise. But with an all-fiber network, you have only half as many electronic parts to worry about, because you get rid of all the hubs. That means there are only half as many pieces of equipment to fail, so the all-fiber network should be twice as reliable. And since all the master electronics is in one space, it's much easier to manage and troubleshoot.

Now we have established fiber's economic superiority, we don't even have to point out how fiber gives you a big advantage in upgrading too, instead of the relentless push to upgrade UTP installations every couple of years(but we did anyway!)

For all the 568 standards "wonks", the EIA/TIA 568 committee has recently issued TSB-72 which recognizes a centralized fiber optic network solution. It offers a simple, reasonable solution for an all-fiber network if you ignore the fact that they just don't seem to understand that fiber doesn't need the "horizontal" and "backbone" nomenclature. But you can tell you customers that an all-fiber network meets the "568" standard. And it may save them lots of money!

PS: Another advantage of fiber will be the new generation fiber optic connectors. They are smaller than the current ST and SC connectors and several of these connectors offer the potential to greatly reduce the cost of fiber optic installations. They are so small, hardly bigger than the cable itself, it may prove feasible to install pre-terminated cables rather than field terminate. And that may be even more cost effective. We'll visit that option in a future column.


© 1999, fotec, inc.

information courtesy of  Fotec Inc and Cable U 

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