Zhone Technologies IMACS-200 - Manual (Page 98)

4-14 General Features
Model No. Running Head Other CPU Settings IMACS-200 General Features
4.4.1 System Clock Source
Figure 4-8.Setting the System Clock Source
The IMACS-200 can be set to source to an incoming timing source from the WAN, the HSU,
the optional OWAN, or on its internal clock. Figure 4-8 shows this setting from the CPU Clock
screen. Choosing one of the three choices and saving the choice will force the system to time
off of that source.
The crafts person can choose a different source for both the Primary and Secondary inputs,
and the current clock field will update to the highest-order clock available. The primary clock
is always the systems first choice, followed by the Secondary clock and then finally the shelf
will internally time. For example, should the primary timing source fail, the system will
automatically switch to the secondary source. Should the primary timing source recover, then
the system will automatically switch back to the primary timing source. Should both the
primary and secondary sources fail, then the IMACS-200 will revert to internally timed. Loss
of the secondary timing source while the primary source is still available will have no impact
to the system operation.