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1000BASE-T Cable Requirements
All Category 5 UTP cables that are used for 100BASE-TX connections should also
work for 1000BASE-T, providing that all four wire pairs are connected. However, it is
recommended that for all critical connections, or any new cable installations,
Category 5e (enhanced Category 5) or Category 6 cable should be used. The
Category 5e specification includes test parameters that are only recommendations
for Category 5. Therefore, the first step in preparing existing Category 5 cabling for
running 1000BASE-T is a simple test of the cable installation to be sure that it
complies with the IEEE 802.3ab standards.
Cable Testing for Existing Category 5 Cable
Installed Category 5 cabling must pass tests for Attenuation, Near-End Crosstalk
(NEXT), and Far-End Crosstalk (FEXT). This cable testing information is specified in
the ANSI/TIA/EIA-TSB-67 standard. Additionally, cables must also pass test
parameters for Return Loss and Equal-Level Far-End Crosstalk (ELFEXT). These
tests are specified in the ANSI/TIA/EIA-TSB-95 Bulletin, “The Additional
Transmission Performance Guidelines for 100 Ohm 4-Pair Category 5 Cabling.”
Note that when testing your cable installation, be sure to include all patch cables
between switches and end devices.
Adjusting Existing Category 5 Cabling to Run 1000BASE-T
If your existing Category 5 installation does not meet one of the test parameters for
1000BASE-T, there are basically three measures that can be applied to try and
correct the problem:
1. Replace any Category 5 patch cables with high-performance Category 5e or
Category 6 cables.
2. Reduce the number of connectors used in the link.
3. Reconnect some of the connectors in the link.
Fiber Standards
The current TIA (Telecommunications Industry Association) 568-A specification on
optical fiber cabling consists of one recognized cable type for horizontal subsystems
and two cable types for backbone subsystems.
Horizontal 62.5/125 micron multimode (two fibers per outlet).
Backbone 62.5/125 micron multimode or singlemode.
TIA 568-B will allow the use of 50/125 micron multimode optical fiber in both the
horizontal and backbone in addition to the types listed above. All optical fiber
components and installation practices must meet applicable building and safety
codes.