Nortel Communication Server 1000S Installation And Configuration Manual page 90

Page 90 of 394 ISDN Primary Rate Interface equipment overview
553-3001-201 Standard 2.00
Tracking mode
In tracking mode, the DDP loop supplies an external clock reference to a
clock controller. Two DDP loops can operate in tracking mode, with one
defined as the primary reference source for clock synchronization, the other
defined as the secondary reference source. The secondary reference acts as a
back-up to the primary reference.
As shown in Figure 30 on
clock controllers (CC-0 and CC-1). One clock controller acts as a back-up to
the other. Lock the clock controllers to the reference clock.
September 2004
page 91, a system with dual CPUs can have two