363-206-295
Circuit Pack Descriptions
7-54 Issue 1 December 1997
Protection Circuitry 7
Optional 1+1 nonrevertive unidirectional line protection switching compliant with
SONET specifications is provided. The 21D/21D-U OLIU is protection switched by
the SYSCTL in response to an external command, incoming signal failure, or
internal equipment fault. The 21D/21D-U OLIU circuit pack is protection switched
with the IS-3 line.
The 21D/21D-U OLIU provides selectors for STS-1 and timing signals from the
TSI circuit packs. The 21D/21D-U OLIU monitors these inputs and selects one as
directed by SYSCTL.
Fault Detection Circuitry 7
The 21D/21D-U OLIU circuit pack has in-service and out-of-service built-in test
capability. An out-of-service test is performed whenever the 21D/21D-U OLIU
resets or is commanded to reset by the SYSCTL through the serial interface.
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 21D/21D-U OLIU circuit pack is inserted or recovers from a
transient failure.
Performance Monitoring 7
The 21D/21D-U OLIU circuit pack provides PM circuitry for the following
performance parameters:
■ Section severely errored frame seconds (SEFS) count
■ Line parameters based on B2 coding violations.
Power Circuitry 7
Power for the 21D/21D-U OLIU circuit pack is provided by a DC-to-DC converter
located on the 21D/21D-U OLIU circuit pack. The converter supplies +5 volts and
−5.2 volts. Both A and B −48 volt backplane busses supply power to the converter
through diode ORed circuit pack-mounted power select circuits and circuit pack-
mounted fuses. A failure of the fuse or converter causes the red FAULT LED to
light.
To Next Page
Loading...
Need help?
General
