Redundancy & High Availability:Clocking

The clock is a necessary component of a TDM network. Synchronizing your system on the right clock, allows it to offer good sound quality.

Clock Sources

The Tmedia can synchronized its TDM network on 3 types of sources:

• BITS
• Line Service
• SONET/SDH Interface

Clock type is determined by the Tmedia model. The availability is shown in the following table:

Models	Clock Source Type
	BITS	Line Service	SONET/SDH Interface
TMG800	N	Y	N
TMG3200-RJ	N	Y	N
TMG3200-TE	N	Y	N
TMG3200-DS3	Y	Y	N
TMG3200-STM1	Y	Y	Y
TMG7800	Y	Y	Y

Clock Redundancy

The TMG-CONTROL allows to configure a system clock references list using the Web Portal. Clock redundancy is accomplished by configuring at least 2 valid clock references in the system. The TMG-CONTROL will scan through the clock references list until it finds a valid one. If the active clock source becomes unavailable, TMG-CONTROL will to the next preferred valid clock source. Clock recovery, which means that the system will switch back to a more preferred clock source if it becomes available again, is an option available through the Web Portal.

Here is an example of a TMG7800 system containing 3 source references:

Even if clock source #1 becomes unavailable, clock source #2 will synchronize the TDM network. As seen in the next example: