The following is a collection of excerpts from a message that I recently received from a colleague.
I have a problem that I would like your assistance in solving. Data cabling is taking an unacceptably large amount of my budget; I am looking to reduce how much I spend on cabling.
The source of the problem is that users want convenience. In a perfect world, voice and data outlets would be as ubiquitous as electrical outlets. There would be an electrical outlet and a voice/data outlet every six feet on every wall, and every three feet on every lab bench.
While this is practical with electrical outlets, there are two reasons it is less practical with data outlets:
- Electrical wiring is expected to last 30 years or more, while data cabling is expected to last at most 5 to 7 years;
- Large numbers of electrical outlets are daisy-chained on a single circuit, while every data cable is a lengthy home run to a telecom room (TR).
Although I'm not familiar with the cost of installing electrical outlets, I speculate that they are much less expensive than data outlets when amortized over their lifetime.
Our current model is to locate all network electronics in as few TRs as possible, and make all cables home runs between the outlets and the TRs. This was cost-effective in the days when electronics were all relatively expensive compared to cabling. We would cable heavily and delay the purchase of switches until we needed them. Switch ports never went to waste because they were all in one TR.
But the per-port price of switches continues to drop, while the cost of cabling is driven up by the increasing cost of labor.
As an example, assume the cost of a 48-port switch is $3,000. The 48 cables plugged into the switch (assuming $180 per cable pull) cost $8,640. If we have one unused cable for user convenience, for each cable plugged into a switch port (and this is a conservative estimate), then we have $17,280 worth of cabling in our walls for each $3,000 switch in our rack. I realize I have left out other costs associated with TRs, but this at least illustrates that cabling is a non-trivial expense.
I also see a degree of waste in cabling that I don't see in network electronics. I fear that five years from now we will be replacing our Category 5e cabling, and at least half of the cables we rip out of the walls and throw in the dumpster will never have been used to transmit data.
Wireless networking may eventually be the solution in some buildings and rooms. But issues like the need for very high bandwidth, and the problem of interference from electrical equipment may mean that wires are with us for a long time.
Fiber could make data cabling as long-lasting as electrical wiring, but the cost of fiber, its installation, and the electronics it plugs into may keep it from being cost-effective for a long time. Hence, I'm asking for your ideas.
My reply:
If you are feeling a big budget bite for the cost of cabling from the network electronics in the TR to the outlets in work areas, there are alternatives available. Move the electronics closer to the work area. No, I don't mean on top of a file cabinet or under someone's desk, but in (for lack of a formal name) a "tiny TR." The model remains the same-fiber backbone from the intermediate crossconnect to the TR, and unshielded twisted-pair horizontal cable from the TR to the work area.
You see, there is nothing within the TIA standards that sets a maximum number of TRs per floor. And while there is most certainly a maximum allowable distance between the horizontal crossconnect in the TR and the work area, there is not a stated minimum distance.
This will, of course, upset your IT support staff, who tend to want all network equipment in one room while they keep the only key. Using managed switches and cabling them back to the core switch in a centralized equipment room will appease some, but others will continue to grumble.
I reserve judgment as to whether this is a good or bad idea, but I can assure you that things will definitely get more complicated.
The state of structured cabling
I still remember the mantra "Level 0ellipse if we build it, the applications will follow." But recently, it seems like structured cabling standards are chasing rather than leading the applications.
In 1985, the structured cabling concept was pretty simple: main crossconnect (MC) to intermediate crossconnect (IC) to horizontal crossconnect (HC) to work area (WA).
In 1996, multi-user telecommunications outlet assemblies (MUTOAs) and consolidation points (CPs) were added to the list. Then there were basically three options:
- MC to IC to HC to WA;
- MC to IC to HC to MUTOA;
- MC to IC to HC to CP to WA.
Fast-forward to 2001, and we are now seeing the introduction of horizontal connection points for building automation systems and point-to-point cabling for industrial environments. The complexion has changed so much that many are beginning to question, "What happened to the structure in structured cabling?"
In 1985, the standards focused on commercial office buildings. Today, we see a broadening of where voice, data, video, control, and security applications are installed-from the boardroom to the bedroom to the factory floor. The standards are merely trying to keep pace.
Category 6, continued
Chapter 1 of the never-ending story of Category 6 is about to come to a close. Earliest possible publication date is February 2002, but my guess is June. What then? Well, Chapter 2, of course.
The soon-to-be-published TIA standard for Category 6 will give you more headroom than Category 5e at 100 MHz, but less than the next generation of Category 6 at 200 MHz. Yes, there will always be a better cabling system on the horizon with a standard to match.
If this seems a little bit like the plot from the movie Groundhog Day, it is. Only, the goal is not to produce the perfect cable, connector, or switch. The goal is to move product through distribution. Cabling-component manufacturers base their production on your perceived obsolescence of your cabling systems. On the other hand, the application-hardware manufacturers tend to build their offerings based on use of the most widely deployed cabling system that can meet their minimum requirements. Why? End users have only so many IT dollars to spend each year, and everyone is striving for the lion's share.
But the best reason I have heard (from a noted telecommunications engineer) as to why there will always be a better cabling system: "I have a wife and little dogs to feed."
And we all thought it was bandwidth, bandwidth, bandwidth.
Donna Ballast is a communications analyst at The University of Texas at Austin and a BICSI registered communications distribution designer (RCDD). Questions can be sent to her at Cabling Installation & Maintenance or at PO Drawer 7580, The University of Texas, Austin, TX 78713; e-mail: [email protected].