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 synchronize 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.

It is worth mentioning that TMG7800 clock is distributed through the system using the TMS network.

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: