Setting Up
4-46
9161-A2-GH30-20
September 1997
Table 4-8.
System Options (3 of 4)
Secondary Clock Source
Possible Settings: Net1, Net2, DSX
ss-p, Internal, External, Sync Data
Default Setting: Internal
Provides a secondary clock source when the primary clock source fails. The source
selected for this configuration option provides all of the timing within the unit and the
clocks for all of the external interfaces. Only one APM clock source can be selected as
the clock source for either primary or secondary clock. The clock source will switch back
to primary when the primary clock source returns and is stable for 10 seconds. If the
secondary clock source fails, the clock source will switch to internal. The clock source
will switch back to primary when the primary clock source returns and is stable for
10 seconds.
NOTE:
For the Primary and Secondary Clock Source options, only Sync Data and
Internal can be selected for both options. All other selections must have
different settings (e.g., if Primary Clock Source is set to Net1, Secondary
Clock Source cannot be set to Net1).
Net1 – The secondary clock for the unit is derived from the Network 1 T1 interface.
Net2 – The secondary clock for the unit is derived from the Network 2 T1 interface.
DSX
ss-p – The secondary clock for the unit is derived from the DSX-1 interface, where
ss is the slot number and p is the port number. This selection is only available if a
DSX-1 interface is enabled.
Internal – The secondary clock for the unit is the internal clock.
External – The secondary clock for the unit is the external clock (XTXC) provided
through one of the synchronous data ports (specified in the Port configuration option).
Only a disabled port can be selected and the port cannot be used for data. This
selection only appears if at least one synchronous data port is disabled.
Sync Data – The secondary clock for the unit is derived from the XTXC signal of a
synchronous data port (specified in the Port configuration options). Only an enabled port
can be selected. This selection only appears if at least one synchronous data port is
enabled.
NOTE:
If an EDL for the port is enabled, the external device must provide a clock
8 kbps less than the expected data port rate. For example, if 64 kbps is the
selected port rate, the external clock source should supply a 56 kbps clock
signal.
Port (for Secondary Clock Source)
Possible Settings: S
ssPp
Default Setting: the first available port
Selects a slot and a port number for the Secondary Clock Source.
Port only appears if Secondary Clock Source is set to Sync Data or External.
S
ssPp – Where ss is the slot number and p is the port number for the Secondary Clock
Source.
