Cabletron Systems 100BASE-FX, Cabling Manual

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FDDI Network Requirements
12-4 TP -PMD (UTP)
Length
Assuming that all other cable quality specifications are met, the FDDI LCF-PMD
allows a low-cost fiber optic link to be no longer than 500 m from station to
station. This total length must include all connectors and patch panels between
the two stations. Keep in mind when determining the maximum length of an
FDDI fiber optic link that the FDDI network may not exceed a total length of
100 km. If the sum of all cable lengths within the network exceeds this 100 km
limit, the FDDI network will experience errors in token rotation timing and other
operations, and be unable to effectively recover from certain cable faults.
Emitted Power
The LCF-PMD specification requires that links meet transmission power
requirements. If these power requirements are not met, the strength of the FDDI
signal will be insufficient for proper recognition and reception. If an FDDI
transmitter does not produce signals with an emitted power of -22 dBm or better,
the signal will have difficulty propagating through the cable effectively and may
not be received properly at the termination of the link.
TP -PMD (UTP)
Cable Type
The demands of the TP-PMD specification are such that only Category 5 UTP
cabling may be used for TP-PMD links. All connectors, patch panels, and other
cable management hardware incorporated in the cable installation must also be
Category 5 compliant in order for the cabling to be viable in a TP-PMD
environment.
Attenuation
The TP-PMD specification allows any FDDI link made over Category 5 UTP
cabling a total end to end loss of 11 dB at a frequency of 100 MHz. Note that
connectors, splices, and passive FDDI devices introduce additional loss into
cables.