363-206-285
Circuit Pack Descriptions
7-108 Issue 3 June 2001
Timing Circuitry 7
Each TG circuit pack sends timing signals to each 22F-type OLIU. Each 22F-type
OLIU monitors the timing inputs from both TG circuit packs. The 22F-type OLIU
normally selects the timing signals from the TG selected by the SYSCTL. Each
22F-type OLIU provides timing signals derived from the incoming optical signal to
both TG circuit packs for line (formerly loop) timing and DS1 output (BITS).
Protection Circuitry 7
Optional 1+1 nonrevertive unidirectional line protection switching compliant with
SONET specifications is provided. The 22F-type OLIU is protection switched by
the SYSCTL in response to an external command, incoming optical signal failure,
or internal equipment fault. The 22F OLIU circuit pack is protection switched with
theOC-3line.
The 22F-type OLIU interfaces with STS-1 signals from the circuit packs in the
main and function unit slots. It selects the signals from the service or protection
slot of each pair as directed by the SYSCTL.
The 22F-type OLIU provides selectors for timing signals from the TG circuit packs,
monitors these inputs, and autonomously selects either TG circuit pack. The
SYSCTL can inhibit autonomous selection and make its own selection.
Fault Detection Circuitry 7
The 22F-type 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 22F-U OLIU has provisionable VT signal degrade and STS signal degrade
BER threshold capabilities for path protection switching.
Performance Monitoring 7
The 22F-type OLIU provides PM circuitry for the following performance
parameters:
â– Section SEFS count
â– Line parameters derived from B2 coding violations
â– STS-1 path parameters derived from B3 coding violations.
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