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Trends in intrabuilding show fiber advantages.

TRENDS IN INTRABUILDING SHOW FIBER ADVANTAGES

The transition from the electronics (copper) world to the new photonics (fiber) world, within a building, has already begun. Telecomm managers and strategists can no longer get by with just tracking the progress of fiber coming down to the desk-top/workstation.

It is no longer five to 10 years out. It has started, and in fact is already alive and healthy at leading-edge users, like Wall Street, manufacturers, universities, and airports. And second-wave users will soon be starting.

In 1989, the end user was down to two options regarding fiber to the desktop:

* Install some fiber now. (Along with high-quality copper.)

* Make it real easy to add fiber in the near future.

An earlier option is no longer viable--namely, to think about fiber, but take no action yet.

There is a new, third option, which is a combo of the above two--namely:

* Install some fiber now, but make it real easy to add even more, and possibly different, fiber later.

More on this in a bit.

Copper Plus Fiber

Unfortunately, during the electronics-to-photonics transition, which will take at least a dozen more years, the desktop will require both copper and fiber, as will risers and interbuilding.

Today it is too early to install just fiber, and too late to get away with just copper. This is one of the prices to be paid for this oncoming transition to fiber and for accommodating the key byword in today's fast-moving telecommunications: "flexibility."

The main way to "future-proof" a building for tomorrow's uncertain telecomm is to provide flexibility. This translates to paying somewhat more up front for new telecomm systems (e.g., cabling, PABXs, LANs, etc.) but reaping reward later.

Users can no longer listen to salespeople say, "You only need to install two unshielded twisted pair (UTP) for my system." Three to four years later, after that system becomes obsolete, the next sales-person likely will require some other media combination, hence an expensive rewire (and possibly an expensive removal of the "old" wire).

So tell the salesperson you appreciate his/her company's cable efficiency, but you will still plan for copper plus fiber. Specifically, the minimum to each desktop should be: 4 UTP + 4 UTP minimum, with 2 fibers optional, and up to 4+4+4+4 UTP, +4-12 fibers.

Why More Than 2?

Two fibers in the absolute minimum. The trend is to 4 minimum, and 6-12 could become common--to each desktop. Resons include:

1. The new FDDI (Fiber Distributed Data Interface) LANs may eventually come directly to many desktops.

FDDI consists of two counter-rotating rings (for reliability) at 2 fibers per ring (xmt + rcv), hence 4 fibers.

2. Throw in a fifth fiber in case one of the four fails. And throw in sixth, because extra fibers in a sheath at that point make minimal cost difference. Some planners even say go for a dozen fibers for that reason. Only terminate fibers used now, to keep initial costs down. The remaining unused "dark fibers" could be terminated later as needed.

What Kind of Fiber?

In 1989 our decision seemed simple. Go with 62.5/125 micron, multi-mode fiber, which had emerged the victor over 50, 80, and 100 micron fibers, where 62.5 micron was a good compromise of numerious fiber characteristics.

But never let it be said that one can rest in telecomm, and especially in cabling. In 1990, along come two more fiber-to-desktop choices:

* Single-mode fiber.

Already, Case Western Reserve University in Cleveland is installing a combo of multiand single-mode fiber (plus copper) to thousands of desktops. Who ever heard of needing single-mode's 1 + GHz to a desktop? We are just getting used to the idea of 10 Mb/s Ethernet, 16 Mb/s token ring, and maybe even upcoming 100 Mb/s FDDI. The answer is that an increasing number of people are thinking 1 Gb/s, and not 10 years out, but five years and sooner.

The driving force includes upcoming information systems requiring cheap, high bandwidth, e.g. for 3D color graphics, imaging, and other applications. CWRU sees single-mode to desktop today providing additional flexibility and future-proofing.

* Plastic fiber.

Finaly emerging and discussed increasingly in trade journals nowadays is plastic fiber, which proponents claim will find at least niches where lower cost and ease of use are important (e.g., automobiles, and possibly broader applications). Hence, we see the need to add a new fiber-to-desktop option for those options previously described above: a combo of the first two.

Easy to Add Fiber

How does a user provide flexibility and accommodate the uncertain, fast-moving telecomm future? How can a minimal additional cost today make it real easy to accommodate later the essentially certain coming of fiber, and more broadly, photonics?

1. Install wider-diameter duct from wall outlet to intermediate distribution frame (IDF)> that is, for "horizontal" cabling. For example, use 1"-diameter EMT or greater, instead of 1/2" or 3/4". Leave in a pull cord.

2. At IDF, plan for floor and wall space to house fiber/photonics components, such as fiber crossconnects, fiber muxes, fiber-to-electronics converters, and other fiber/photonics components. Actually engineer and lay out for this now, but do not install it all yet.

Add extra power, HVAC, security, fire system, and other fiber support. This means leaving significant empty space at cutover time, for future fiber/photonics. This is a reason why today's IDFs are typically 10' x 10' minimum, and even 12' x 16', instead of traditional 6" holes in walls.

Architects, facilities managers, and others may initially object, until educated on the subject. But it is case of "pay me now or pay me later."

3. Provide spare duct/raceway capacity for IDF-IDF and IDF-MDF runs (intrabuilding "riser") plus interbuilding ducts. Fortunately, fiber cable is very compact, requiring less duct/raceway per unit than traditional copper.

4. Change your thought process to consider fiber as "normal." Accept the fiber onslaught. Don't fight it. Be willing to invest now in fiber to gain big ROI over the coming years--even though this goes against the "one-year payback syndrome" which unfortunately has become common with decision makers in the U.S.

100 Mb/s STP & UTP

The major jumps in 1990 of UTP and STP (unshielded and shielded twisted pair) capacity to 16, 20, and now even 100 Mb/s should be viewed positively, as providing another option for users, and complementing fiber.

Granted, these copper advances may in certain specific user instances delay fiber, but they cannot stop fiber. For example, a user who wants 100 Mb/s FDDI in a new or refurbished building should go directly to fiber (as well as UTP), because fiber offers much more bandwidth and distance, for long-term flexibility. Fiber is "idling" at 100 Mb/s> STP and UTP, even "enhanced," would be pushing their upper limits.

Jump on the fiber bandwagon if you have not already. If you already have, move now to the center.
COPYRIGHT 1990 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1990 Gale, Cengage Learning. All rights reserved.

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Title Annotation:includes related article on photonics; intrabuilding wiring
Author:Morgan, James H.
Publication:Communications News
Date:Dec 1, 1990
Words:1158
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