High Availability:Hardware: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 Toolpack system can synchronized the system on 3 types of sources:

• BITS port (Available on TMP7900 telecom units and TMP6400 with DS3 or SONET/SDH mezzanine. Also available on the TMP7900-TMS)
• Line Service
• SONET/SDH interface

Choosing Clock Reference

Always place the most reliable clock source at the top of the clock references list in the web portal. This will avoid unnecessary clock switch over. TelcoBridges recommend to synchronize the clock on the BITS port when available. If your system includes TMP7900-TMS, it is recommended to use the TMP7900-TMS BITS ports as clock sources.

When the system selects a clock, it will only use clock sources that are valid and that it is available on an active device of the system. For example, in a system containing 2 TMP7900-TMS ( one will be active, the other standby ) the clock sources on the standby TMP7900-TMS (BITS ports) will not be selected. In the figure below the clock source #3 and #4 won't be selected as system clock unless the standby TMP7900-TMS becomes active.

Clock Redundancy

The system clock is configured using the Toolpack web portal. Toolpack allow the system to have a system clock references list. Clock redundancy is accomplished by configuring at least 2 valid clock references in the system. The system will scan through the clock references list until it finds a valid one. If the active clock source becomes unavailable, the system will scan through the clock reference list again to found another valid clock source. Clock recovery, which means that the system will switch back to a more preferred clock source if it becomes available again, can be configured in TMS network.

Another redundancy feature for the system clock is the 2 BITS ports which can be assigned to different clock source.

Recommended Setup

Here is an example of a system clock where 2 TMP7900-TMS and the system has selected the clock source #1 as system clock:

References

NOTE:These references assume that your system is running at least on Toolpack v2.3. For configuring the system, please select the appropriate Toolpack Web Tutorial Guide.