Avaya S8700 Maintenance Manual page 1326

Maintenance-Object Repair Procedures
Loss of Signal Alarm Inquiry Test (#138)
This test verifies the synchronization status and continuity of the DS1 link. The
Loss of Signal alarm indicates that the DS1 Interface circuit pack is unable to
derive the synchronization clock from the DS1 facility. When the DS1 Interface
circuit pack detects a Loss of Signal alarm, it stops providing the synchronization
clock for the system if it is administered as a timing source and transmits a Yellow
alarm to the remote DS1 endpoint.
When the Loss of Signal alarm is confirmed, the maintenance software places all
trunks or ports of the DS1 Interface circuit pack into the out-of-service state. The
inquiry test will run every 10 minutes until the loss of signal has been restored.
The DS1 Interface circuit pack raises a Loss of Signal alarm after the signal has
been lost for about 1second. It will not retire the alarm until the signal has
returned for about 10 seconds.
This test is also used to maintain the 120A CSU module and the 401A T1 sync
splitter. The CSU module, when combined with the functionality provided by the
TN767E circuit pack, provides functionality equivalent to an external standalone
ESF T1 CSU The 401A T1 sync splitter, when combined with the functionality
provided by the TN767E circuit pack, allows an ATM switch to derive its timing off
a T1 facility connected to the S8700 Multi-Connect's DS1circuit pack.
If a TN767E circuit pack detects certain I-CSU/T1 sync splitter hardware errors, it
will notify the maintenance subsystem. When the subsystem receives notification
of the error, it executes this Loss of Signal Inquiry test. The test, in addition to
querying for a Loss of Signal alarm condition, will also query the TN767E board to
confirm the error. A Minor or Warning alarm will be raised depending on the
severity of the error. The trunks on the board may be taken out of service if the
error is deemed serious.
If a Loss of Signal alarm and an I-CSU/T1 sync splitter error co-exist, the Loss of
Signal alarm condition takes priority, and the board and all of its trunks are put in
the out-of-service state. However both errors will be logged.
When the maintenance subsystem receives notification that the ICSU/T1 sync
splitter hardware error condition no longer exists, maintenance will restore the
board and all trunks to their previous service state if the alarm can be cleared (no
other errors or Loss of Signal alarm exist).
8-604 Issue 1 May 2002 555-233-143