363-206-285
Circuit Pack Descriptions
7-132 Issue 3 June 2001
Power Circuitry 7
Power for the 24G-U OLIU circuit pack is provided by two DC-to-DC converters
located on the 24G-U OLIU circuit pack. The converters supply both +5 and +3.3
volts. Both A and B −48 volt backplane busses supply power to the converters
through diode ORed circuit pack-mounted power select circuits and a circuit pack-
mounted fuse. Failure of the fuse or converters causes the red FAULT LED to
light.
24G-U OLIU Quick Reference Summary 7
Transmit Functions 7
Major transmit functions of the 24G-U OLIU circuit pack are as follows:
â– Selects STS-1 inputs from MXRVO, DS3, STS1E, or other OLIU circuit
packs
â– Provides VT1.5/STS-1 signal cross-connections
â– Adds SONET transport overhead and, for up to three VT1.5 cross-
connected STS-1s, adds STS-1 path overhead
â– Byte-interleaves and scrambles up to three selected STS-1 signals plus the
other nine to twelve STS-1s on the ring to produce an STS-12 signal
â– Uses a laser transmitter to produce a SONET standard OC-12 optical
signal from an STS-12 electrical signal.
Receive Functions 7
The following are major receive functions of the 24G-U OLIU circuit pack:
â– Receives a SONET standard OC-12 optical signal and converts it to an
electrical STS-12 signal
â– Extracts STS-12 clock and retimes the received data
â– Demultiplexes the STS-12 signal into twelve STS-1 signals
â– Extracts transport overhead and, for up to three STS-1s (if VT1.5 cross-
connected), extracts path overhead
â– Processes the STS-1 or STS-3c pointers and frame-synchronizes the
STS-1/STS-3c signals
â– Processes the VT1.5 pointers and frame-synchronizes the VT1.5 signal, if
VT1.5 cross-connected, for up to three STS-1s
â– Provides VT1.5/STS-1 signal cross-connections for up to three STS-1s
â– Provides STS-1/STS-3c pass-through cross-connections for remaining
STS-1s
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