Is structured cabling getting a bad case of the “whys”?

There is a certain stage in a young child's life when no matter what is said to them, they ask, "Why"

Jun 1st, 2006
Th 212070

There is a certain stage in a young child’s life when no matter what is said to them, they ask, “Why?”

And users and owners of structured cabling systems in general, and standards-compliant structured cabling in particular, have reached a point where they are beginning to ask the “why” questions:

• Why do I need a copper cable first, and then I can add a fiber cable?
• Why do I need to limit my fiber horizontal to 90 meters?

If you have a particular ”why” that you would like to have added to this list, send it to me and I will address it here as time and space permits.

The last TIA TR-42 meeting that I attended was in February in Palm Springs, CA. As I was making my way for the gate to the luggage carousel at the airport, I noticed an advertisement in which a trendy-looking young man was in a business suit, dancing. The caption read: “Wired is so yesterday.”

It is my opinion that while the networks of tomorrow may not be “wired,” they will be cabled. Not to the extent that they are today-to the end-user interface device or even to the network hardware feeding that device-but there is simply not sufficient spectrum allocated to accommodate all communications over wireless.

In April, the TR-42 editors met for three days of long and, at times, heated discussions, followed by weeks of final tweaking-and now, the first draft of PN-3-0177 and SP-3-4425-RV3 are ready for their full technical committee debut, which was scheduled to begin June 5 in Alexandria, VA.

PN-3-0177 will become TIA-568-C.0 Generic Customer-Owned Telecommunications Networks, and SP-3-4425-RV3 will become the new revision TIA-568-C.1 Commercial Building Telecommunications Cabling Standard.

Together, TIA-568-C.0 and TIA-568-C.1 will replace ANSI/TIA/EIA‑568‑B.1 2001 and its addenda.

TIA-568-C.0

Rather than us having to sort out horizontal versus outlet cable as well as intra- and inter-building backbone cabling, the functional elements of the new “generic telecommunications cabling system structure” are being described as “levels” of cabling between “connection points.” I would expect the term “level” to change given its previous use, and I will update here with whatever it changes to.

The cabling “recognized” in TIA-568-C.0 includes singlemode and multimode optical-fiber cable that will be specified in TIA-568-C.3, and 100-Ω twisted-pair cable that will be specified in TIA-568-C.2. Currently in TIA-568-C.0, there is no requirement for multiple runs, nor that any particular type of cabling is used. These requirements will be within the “unique premises environments” standards that were mentioned here in April. The current list includes TIA-568-C.1 Commercial, TIA-570-C Residential, TIA-942-A Data Centers, and TIA-1005-A Industrial. Others are expected.

The current draft of TIA-568-C.0 absorbs and tweaks a bit the technical content of:

ANSI/TIA/EIA‑568‑B.1‑1, Addendum 1-Minimum 4-pair UTP and 4-Pair ScTP patch Cable Bend Radius;
• ANSI/TIA/EIA‑568‑B.1‑2, Addendum 2-Grounding and Bonding Specifications for Screened Balanced Twisted-Pair Horizontal Cabling;
ANSI/TIA/EIA‑568‑B.1‑3, Addendum 3-Supportable Distances and Channel Attenuation for Optical Fiber Applications by Fiber Type;
• ANSI/TIA/EIA‑568‑B.1‑7, Addendum 7-Guidelines for Maintaining Polarity Using Array Connectors;
• TIA/EIA TSB125, Guidelines for Maintaining Optical Fiber Polarity Through Reverse-pair Positioning;
• TIA TSB140, Additional Guidelines for Field-Testing Length, Loss and Polarity of Optical Fiber Cabling Systems;
• TIA TSB153, Static Discharge Between LAN and Data Terminal Equipment.

TIA-568-C.1

The horizontal cabling “recognized” in TIA-568-C.1 includes either 62.5/125-µm or 50/125-µm multimode optical-fiber cable that will be specified in TIA-568-C.3, and four-pair 100‑Ω unshielded twisted-pair (UTP) or screened twisted‑pair (ScTP) Category 3, 5e, or 6 cables that will be specified in TIA-568-C.2. There is a requirement for a minimum of two horizontal cabling runs but no requirement that any particular type of cabling be used. Translation: One four-strand fiber cable to each work area meets this requirement.


The draft TIA-568-C.0 specifications currently use generic terminology, including "connection point" and "level," rather than specific references to inter- or intra-building cabling, horizontal, and outlet.
Click here to enlarge image

The backbone cabling “recognized” in TIA-568-C.1 includes singlemode and either 62.5/125-µm or 50/125-µm multimode optical-fiber cable that will be specified in TIA-568-C.3, and 100‑Ω unshielded twisted-pair Category 3, Category 5e, or Category 6 cables that will be specified in TIA-568-C.2. There is no requirement that any particular type of cabling be used. Translation: An all-fiber backbone meets this requirement.

The current draft of TIA-568-C.1 absorbs, and here again tweaks a bit, the technical content of:

• ANSI/TIA/EIA‑568‑B.1‑4, Addendum 4-Recognition of Category 6 and 850-nm Laser-Optimized 50/125-µm Multimode Optical Fiber Cabling;
• ANSI/TIA/EIA‑568‑B.1‑5, Addendum 5-Telecommunications Cabling for Telecommunications Enclosures.

Missing from the new TIA-568-C.1 version of the Commercial Building Telecommunications Cabling Standard are anything deemed by the editors to be “generic requirements” because we will now have TIA‑568‑C.0, and any information regarding 150-Ω STP and Category 5 cabling. So, if you have any of this cabling in your facilities today, you will need to keep the “old” standard as a reference. Yes, that means that you will need to keep your old one and have the two new ones to have a “complete” set of information. But this should work itself out over the next 3 to 5 years.

Notice how easy it would be to have Category 3 and Category 5e simply disappear? Should the TR-42.7 formulating group, most of whom are engineers who are representing cabling manufacturers, vote to de-list such “outdated” cabling, in favor of Category 6 and Category 6a, then the two most widely installed cabling types in recent history would first be relegated to an annex for a cycle, as was Category 5, and then…they are gone. I believe the term that best describes this is “planned obsolescence.”

Or maybe not. The IEEE, another larger group of engineers who are representing network hardware manufacturers, wants to keep the Category 5 specification “alive.” Why? Because they can, and do, produce equipment that can use the older cabling. Translation: The limited IT budget can go into more hardware if it does not require new cabling.

DONNA BALLAST is BICSI’s standards representative, and a BICSI registered communications distribution designer (RCDD). Send your question to Donna at: dballast@swbell.net

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