Nortel Communication Server 1000S Maintenance Manual page 16

Page 16 of 210 PRI fault clearing
553-3001-517 Standard 2.00
System software checks every 0-15 minutes (programmable) to see if a
clock-controller or reference-clock error has occurred.
If the 0-15 minute check finds the PRI in local alarm was a primary clock
source, the software switches the clock controller to the secondary reference.
Channel restoration
When the alarm condition improves, the PRI is restored to service as follows:
1 The local alarm is cleared.
2 After 11 seconds, the PRI stops sending a remote alarm indication to the
far end.
3 The D-channel automatically attempts to re-establish. If this is
successful, the B-channels are placed into the idle state and made
available for calls.
Figure 1 on page 17
(local and remote) alarm timers.
September 2004
shows the progression of the system Red and Yellow