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076R155-000
SpectraComm 553 Fractional T1 DSU
C-1
Issue 7
Installation and Operation Manual
Appendix C:
Alarm Definitions
Overview
This appendix describes the SC 553 DSU alarms:
Network OOF
(Network Out of Frame)
Network LOS
(Network Loss of Signal)
Network AIS
(Network Alarm Indication Signal)
Network USS
(Network Unavailable Signal State)
Network BPV
(Network Bipolar Violations)
Network CRC
(Network Cyclic Redundancy Checksum)
Network RYEL
(Network Received Yellow Alarm)
Network LAD
(Network Low Average Density)
Timing Loss
(Loss of Transmit Timing Source)
Cascade OOF
(Cascade Out of Frame)
Cascade LOS
(Cascade Loss of Signal)
Cascade USS
(Cascade Unavailable Signal State)
Cascade AIS
(Cascade Alarm Indication Signal)
Cascade BPV
(Cascade Bipolar Violations)
Cascade CRC
(Cascade Cyclic Redundancy Checksum)
Cascade RYEL
(Cascade Received Yellow Alarm)
DCD Loss
(Channel Data Carrier Detect Loss)
DSR Loss
(Channel Data Set Ready Loss)
DTR Loss
(Channel Data Terminal Ready Loss)
External Tx Clock Loss (Channel External Transmit Timing Loss)
RxD No Transitions (Channel Receive Data No Transitions)
TxD No Transitions (Channel Transmit Data No Transitions)
EEPROM Checksum (Configuration Error)
Front Panel Test
(Test Mode Commanded from Front Panel)
Unit Failure
Unsolicited Test
(Test Mode Commanded from STC)
Power Up
Config Change
Top Supply Fail
Bottom Supply Fail
Remote Not Responding
Redundant Mode
The DSU also accumulates alarm counts, which can be displayed by an SNMP controller. The
descriptions of the alarms that appear on the following pages treat the Network and Cascade alarm
conditions together. Both categories are concerned with conditions that affect T1 signalling.