Cabletron Systems 100BASE-FX, Cabling Manual

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TP-PMD (STP) 12-5
FDDI Network Requirements
Length
TP-PMD cabling which is within all other requirements of the specification may
be no longer than 100 m from station to station. This total length must include all
connectors and patch panels between the two stations. As with fiber optic
connections, it is important to remember the 100 km total ring length of FDDI
networks when planning installations.
TP-PMD (STP)
Cable Type
The TP-PMD specification demands cables of very high quality. The STP cable
type which has construction characteristics that are of sufficient quality for the
TP-PMD specification is IBM Type 1 STP cabling.
As IBM Type 1 cabling is made up of only two pairs of wire, the TP-PMD
specification details the use of STP cabling for Single Attached Station connections
only. The use of STP cabling to configure a dual counterrotating ring is not in
compliance with the TP-PMD specification, and such a connection will not
provide a failover path for transmission and reception of network signals.
Attenuation
The TP-PMD specification allows any FDDI link made over Type 1 STP 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.
Length
TP-PMD cabling that is within all other requirements of the specification may be
no longer than 100 m from station to station. This total length must include all
connectors and patch panels between the two stations. As with fiber optic
connections, it is important to remember the 100 km total ring length of FDDI
networks when planning installations.