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TDM-CLK (TDM Bus Clock)
Issue 4 May 2002 10-1721 555-233-123
TDM-CLK (TDM Bus Clock)
NOTE:
Replacing the tone/clock circuit pack requires a special procedure described
in the documentation for TONE-BD. That section also describes the LED
displays for this board.
The Time Division Multiplex (TDM) Bus Clock resides on the Tone-Clock circuit
pack, providing clocking signals both for the TDM Bus and the LAN Bus. The
Tone-Clock circuit pack is a critical component in the system and is necessary to
ensure the operation of all port circuit packs in the system. The TDM buses of the
PPN and any EPNs are synchronized together. The system timing reference can
be derived internally from the Tone-Clock circuit pack 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 pack aids in monitoring and selecting
synchronization references. The Tone-Clock circuit pack, after detecting that the
external source of timing is not valid, will automatically begin its escalation
procedure, according to the facilities administered.
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 pack, switching back to a Stratum 3 Clock must be
initiated by a technician after the external reference has been repaired.
MO Name (in
Alarm Log)
Alarm
Level Initial Command To Run
1
1 UU is the universal cabinet number (1 for PPN, 2 -3 for EPNs). 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