Toolpack v2.3:Clocking Sources
From TBwiki
The Tmedia/Tdev system requires that all of its component Tmedia/Tdev devices be in synchronization with each other.
With an eye on flexibility, clocking sources can be configured to be generated from either internal clocking sources originating from any Tmedia unit or from more reliable clocking sources, such as a T1 line. In addition, multiple clocking sources can be configured in order to guarantee against the failure of any one clocking source causing system synchronization problems. A conceptual illustration is provided below.