Information Technology Reference
In-Depth Information
must be sure that the fiber cable you specify is rated for laser operation, as well as
extended bandwidth (the bandwidth-distance product). Such fiber is often called
gigabit-ready
or
laser-compatible
.
If you have existing multimode fiber, you may have to use a short
conditional
launch adapter
cable to spread the single-mode laser source to multiple modes. The
bad news is that the adapter may add from $50 to $100 to the cost of your installa-
tion. If you suspect that there may be a problem with your older multimode cable, you
may still be able to use 1000BaseSX, as many of the transceivers for this technology
include built-in mode conditioning. Check with your equipment manufacturer.
The basic principle of the standardized cabling infrastructure is predictability. A
strong measure of network integrity and reliability can be realized by utilizing a
standards-based cabling system. Much has been said about the value of providing a
structured cable plant that meets recognized standards for copper cable installa-
tions. A standards-based installation for fiber-optic cabling is just as important.
Manufacturers of networking equipment depend on the cable standards of the TIA
and the operating standards of the IEEE, among others, for the compatibility and
performance parameters of their products. The cabling designer and network man-
ager depend on these standards as well.
With an inside cable plant that is designed and installed according to the stan-
dards, you can be assured that the equipment you purchase will operate properly to
the limits specified. Actually, the two types of standards work in concert to bring the
performance of the network up to the necessary levels. The TIA committees care-
fully consider the existing and planned LAN technology innovations when they cre-
ate their cable standards. Likewise, the IEEE standards committees consider existing
and planned cabling standards and the ability of emerging networking technologies
to use these widely deployed cabling plants.
Initially, the network technologies that were to be supported required modest
performance parameters to support networks with 10 to 20 MHz bandwidths.
However, that speed target has moved rapidly upward until we find the standards
now supporting link testing limits of 100 MHz, 250 MHz, and even 600 MHz. As
the cabling standards have moved forward, the ability to place these higher-speed
networks on the cable plant has advanced as well. Fiber-optic cabling is an impor-
tant part of cabling technology and adds to the wealth of options available to the
network technologist.
Although fiber-optic cabling has an inherent bandwidth advantage over copper
in many applications, it is still subject to standards of installation and operation.
