Nortel Communication Server 1000 Manual page 104

104 Integrated Digital Access (IDA) equipment
Reference clock errors
System software checks at intervals of 1 to 15 minutes to see if a clock
controller or reference-clock error has occurred. (The interval of this check
can be configured in LD 73).
In tracking mode, at any one time, there is one active clock controller
which is tracking on one reference clock. If a clock controller error is
detected, the system switches to the backup clock controller, without
affecting which reference clock is being tracked.
A reference-clock error occurs when there is a problem with the clock
driver or with the reference clock at the far end. If the clock controller
detects a reference-clock error, the reference clocks are switched.
Automatic clock recovery
A command for automatic clock recovery can be selected in LD 60 with
the command EREF.
A DDP2 loop is disabled when it enters a local-alarm condition. If the
local alarm is cleared, the loop is enabled automatically. When the loop is
enabled, clock tracking is restored in the following conditions:
•
If the loop is assigned as the primary reference clock but the clock
controller is tracking on the secondary reference or in free-run mode, it
is restored to tracking on primary.
•
If the loop is assigned as the secondary reference clock but the clock
controller is in free-run mode, it is restored to tracking on secondary.
•
If the clock check indicates the switch is in free-run mode:
—
—
Note:
it resumes tracking on a reference clock unless the clock-switching
option is disabled (LD 60, command MREF), or the reference clock is
"undefined" in the database.
Tracking is restored to the primary reference clock if defined.
If the primary reference is disabled or in local alarm, tracking is
restored to the secondary reference clock if defined.
If the system is put into free-run mode by the craftsperson,
Nortel Communication Server 1000
DASS2 Fundamentals
NN43001-571 04.01 4 June 2010
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