Nortel Networks NN43001-301 manual Clock Controller primary and secondary tracking

50ISDN Primary Rate Interface equipment overview

Tracking mode In tracking mode, the DDP2 loop supplies an external clock reference to a clock controller. Two DDP2 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 18 "Clock Controller primary and secondary tracking" (page 50), a system with dual CPUs can have two clock controllers (CC-0 and CC-1). One clock controller acts as a back-up to the other. The clock controllers should be completely locked to the reference clock.

Figure 18

Clock Controller primary and secondary tracking

Free run (non-tracking) mode The clock synchronization of the system can operate in free-run mode if:

•no loop is defined as the primary or secondary clock reference,

•the primary and secondary references are disabled, or

•the primary and secondary references are in local (near end) alarm

Nortel Communication Server 1000

ISDN Primary Rate Interface Installation and Commissioning

NN43001-301 02.03 Standard

Release 5.5 7 December 2007

Copyright © 2003-2007, Nortel Networks