363-206-285
Circuit Pack Descriptions
Issue 3 June 2001
7-139
the SYSCTL detects a fault on the active 26G2-U OLIU, and the companion
26G2-U OLIU is good.
The 26G2-U OLIU interfaces via VT-G signals with circuit packs in the low-speed
slots. It selects the signals from the service or protection slot of each pair as
directed by the SYSCTL.
Fault Detection Circuitry 7
The 26G2-U OLIU circuit pack has in-service and out-of-service built-in test
capability. In-service testing is continuous, and errors are reported when they
occur to the SYSCTL via the intra-shelf control bus. An out-of-service test is
performed whenever the OLIU circuit pack is inserted or recovers from a transient
failure.
The 26G2-U OLIU has STS-1 and VT1.5 signal degrade protection switching and
STS signal degrade protection switching capabilities.
Performance Monitoring 7
The 26G2-U OLIU provides PM circuitry for the following performance
parameters:
â– STS-1 section severely errored frame seconds (SEFS)
â– Line coding violations (B2 parity)
â– Line errored seconds
â– STS-1 path coding violations (B3 parity)
â– STS-1 path errored seconds
Power Circuitry 7
Power for the 26G2-U OLIU circuit pack is provided by two DC-to-DC converters
located on the 26G2-U OLIU circuit pack. The converters supply +5 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.
The 26G2-U provides +5V power to the low-speed slots. Failure of the fuse or
converters causes the red FAULT LED to light.
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