Cabletron Systems 100BASE-FX, Cabling Manual

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12-1
Chapter 12
FDDI Network Requirements
This chapter details the test specifications and limitations for media used in FDDI networks.
MMF-PMD
Cable Type
The FDDI PMD specification that deals with multimode fiber optic cabling in
FDDI environments specifies the use of 62.5/125
µ
m fiber optic cabling which is
designed for use with 1300 nm wavelengths. Other sizes of fiber optic cabling
may be used with MMF-PMD compliant products, but the performance of links
made with these nonstandard cables will be reduced.
Attenuation
The FDDI specification allows any FDDI link made over multimode fiber optic
cabling a total end to end attenuation of 11 dB at a wavelength of 1300 nm. Note
that connectors, splices and passive FDDI devices introduce additional loss into
cables. When estimating total loss, assume a loss of 0.5 dB for any splice or
connector other than those at the end stations. If an optical bypass switch is
included in the cable segment, the switch introduces additional loss, usually
2.5 dB.