The Folly of Future-Proofing Layer 1
When designing cabling infrastructure, is Category 6a to the desktop really the best choice?
Last month at the annual SCTC conference, I gave a speech on developments with Layer 1 (from the OSI model) technology. Although there are many intriguing technical functions that reside in Layer 1, most people think of copper and fiber cabling. Well, that's fine by me, because cabling is the subject I'd like to discuss today.
During my speech, I challenged the consultants in attendance to consider the baseline recommendation for copper cabling to the desktop. Without giving it much thought, most customers are led to believe that Category 6a cabling is the obvious preference -- it is the default choice of the cabling industry.
However, there are many factors that should be analyzed before blindly following the "latest is greatest" philosophy. Among other things, the two most critical questions to ask are:
- What is the expected life span of the space being cabled?
- What are the needs of the users?
It is often stated that the reason to go with 6a is to "future-proof" the space being wired. If only that were true! Past attempts to future-proof the physical layer have, in hindsight, been almost laughably short-sighted.
We had one developer company in the mid-1980s that wanted its new building to be capable of handling any current and future client need. They requested we design the building in a way that every outlet would be fed with a standard telephone cable, IBM Type 2 cable, twin-ax cable, RG-58 coaxial cable, RF-59 coaxial cable, and 62.5 multi-mode fiber pair. Fortunately, we talked them out of such a cabling plan; and within only 10 years every cable identified by the developer was no longer current technology for the applications they were designed to serve.
In 1990 we had a client constructing a new building that decided to install a composite cable with two copper cables and a multi-mode fiber cable to future-proof the installation. We suggested saving money by not terminating the fiber until it was actually needed (leaving it coiled in the surface-mount outlet boxes) -- 25 years later, the fiber has still never been used and the copper has been surpassed by improved versions.
We have also seen clients invest large sums in cabling buildings that were later abandoned as part of a relocation, sub-leased due to changes, or completely remodeled. When long-term plans are uncertain, it is even more important to consider what cable technology represents the best investment decision for your business. In such cases, the immediate needs of the users is a more important criteria than projecting future needs.
When looking to the future, some have argued that individual users will almost never be able to consume more sustained bandwidth than one Gigabit per second. Machine-to-machine interactions, especially multi-port connections like those in a data center, can produce the volume requiring "big pipes." But even users with extremely large local files and high-pixel count video needs, today, rarely will notice any difference between cable types.
There are many limitations that impact throughput far more than the cable pathway. Any user can tell you how slow (measured in minutes) it takes to download a large file from a central source. This is because of the far-end contention, network latency, input/output delays, read/write time to disk, etc. Increasing the speed of the shortest link with the least contention is like buying a racecar to retrieve the mail at the end of the driveway.
If the individual users ever need more than a 1 Gigabit connection to the desktop, will 6a be the right cabling technology to deliver it? Category 7a delivers even better performance and includes shielding that helps block RF interference. The TIA committee, TR-42.7, is working on the Category 8.1 cable standard. How can 6a be considered future-proof when technology developments are moving so rapidly? Perhaps the optic transceivers will drop in price such that fiber to the desktop eventually becomes the preferred cabling standard. And it is clear that wireless technologies will continue to replace our wired connections. With the future unknown, consideration should be given to the actual cost and value of moving to 6a cable compared to an uncertain future benefit.
Category 6a cabling is more expensive than 5e in several ways, beginning with the fact that the copper is 22 gauge instead of 24 gauge:
- 6a needs more raw materials (copper) and costs more per foot to manufacture
- 6a requires more expensive termination hardware
- Installation is more labor intensive and requires more precise terminations
- As a thicker cable, 6a requires more room in conduits, risers, furniture raceways, etc.
The only tangible benefit of 6a over 5e is the future potential support of 10Gb to the desktop, but the number of users who might need such a connection is very speculative at this point.
Many firms we have worked with agree that a gigabit connection is more than adequate for their users -- and will be for quite some time. Thus, implementing affordable Category 5e cable represents the fiscally responsible choice. Even one of the world's largest software firms (with enough money to buy whatever cable they want) uses 5e as the desktop standard because it makes sense -- and cents.
Many IT shops have already convinced the business to invest in Category 6a cabling as a standard and are not going to backtrack now. However, if the only justification was future-proofing, this is shaky reasoning. In fact, it may be nearly impossible to "future-proof" any process or decision nowadays, with the rate of change so rapid.
For those still facing a decision, the specifics of the cabling situation should be examined carefully rather than blindly following the philosophy that the most popular is automatically the best value.
"SCTC Perspectives" is written by members of the Society of Communications Technology Consultants, an international organization of independent information and communication technology professionals serving clients in all business sectors and government worldwide.