Avaya S8700 - TDM-CLK (TDM Bus Clock)

Maintenance-Object Repair Procedures
555-233-143
8-1604 Issue 1 May 2002
TDM-CLK (TDM Bus Clock)
NOTE:
Replacing the Tone-Clock circuit pack or the IPSI requires a special
procedure described in the documentation for ‘‘TONE-BD (Tone-Clock
Circuit)’’ on page 8-1659. That section also describes the LED displays for
these circuit packs.
The Time Division Multiplex (TDM) Bus Clock resides on the Tone-Clock circuit,
providing clocking signals both for the TDM bus and the LAN Bus. The
Tone-Clock circuit is a critical component in the system and is necessary to
ensure the operation of every port circuit pack in the system. The TDM buses of
every EPNs is synchronized together. The system timing reference can be
derived internally from the Tone-Clock circuit in any PN, or from an external
(off-board) timing reference. Currently, the TDM bus Clock supports
synchronizing the TDM bus with interface rates from Digital Signal 1 (DS1)
facilities as primary or primary and secondary references, and from Stratum-3
clock (STRAT-3) facilities. Only the TN780 tone-clock supports a Stratum-3 clock.
Moreover, the Tone-Clock circuit aids in monitoring and selecting synchronization
references. The Tone-Clock circuit, after detecting that the external source of
timing is not valid, will automatically begin its escalation procedure, according to
the facilities administered. In the following table, successive losses of signal
cause escalation from left to right.
NOTE:
Switching back to a DS1 source is handled by synchronization maintenance,
once any problems with it have been corrected and tested. However, once
synchronization has been switched to the internal timing source of the
master Tone-Clock circuit, switching back to a Stratum-3 clock must be
initiated by a technician after the external reference has been repaired.
MO’s Name (in
Alarm Log) Alarm Level
Initial SAT Command to
Run
1
1. UU is the universal cabinet number (1–64 for ATM PNC, 1–44 for CSS PNC). C is the carrier
designation (A, B, C, D, or E).
Full Name of MO
TDM-CLK MAJOR test tone-clock UUC short TDM bus Clock
TDM-CLK MINOR test tone-clock UUC short TDM bus Clock
TDM-CLK WARNING release tone-clock UUC TDM bus Clock