Information Technology Reference
In-Depth Information
Although structured standards still spec the 100 m limit, it would be just as
practical to double or triple this distance limit for even the most rigorous high-speed
network requirements. Not only has multimode fiber been able to handle 100 and
1000 Mbps networking, but it can also support multimode 10 Gbps at over 300 m,
and single-mode fiber can go 10 Gigs at 10 km!
Fiber connector technology has been refined to greatly reduce interconnection
losses, and to minimize reflections at the connections. This means that systems that
use full-duplex transmission/reception on each fiber are feasible, and that the fiber
may be used in critical applications such as CATV, where minor reflections can cause
serious problems. In addition, quick-connect fiber connectors are being offered that
decrease costs, assembly labor, and required training for fiber termination.
The popular TIA/EIA-568-C standard still requires only two cables to each
workstation. One must now be Category 5e or above, and is presumably targeted
for conventional telephone connection (either analog or digital ISDN). The other
cable may be Category 5e or better, or it may be an accepted fiber. Why not choose
both? Until IP telephony is in widespread use, you will probably still need to pro-
vide the Category 5e or better cable for telephone use. But why choose between cop-
per and fiber for your data?
Here is an ideal scenario for LAN wiring for your future. Run two Category 6
(or 5e or AC6) cables and a 2-pair fiber-optic cable to each work area outlet. You
could actually use a fiber cable with one multimode pair and one single-mode pair
if you really wanted to be ready for future applications. Or, you could use one
62.5/125 pair and one 50/125 pair, both multimode. Fiber core specs are critical in
multimode fiber. A 50 ยต-core fiber can handle greater speeds at the same distances
or the same speeds at greater distances. It never approaches single-mode, but makes
10 Gbps at 100 m practical, and 1000 MHz at 300 m a snap.
Use a modular, four-jack connector plate. Now you have two copper cables,
either of which will run virtually all voice, and high-speed data technologies, and
you have the flexibility of using fiber for high-speed data or even video.
Chapter 11 contains a lot of additional information on fiber-optic cabling
options. Fiber-optic cabling is clearly in our networking future.
In a paraphrase of Mark Twain, the report of the demise of copper wire is greatly
exaggerated. There has been a great deal of press for several years that copper wire
cabling should be abandoned in favor of either fiber-optic cabling or wireless net-
working. While the claims of the proponents are not without merit, they are also
not unbiased. The loudest supporters of copperless networking are the companies
