Avaya S8700 Maintenance Manual page 2014

Maintenance-Object Repair Procedures
PNC Interchanges
PNC spontaneous interchanges occur when PNC duplication software determines
that the SOH of the standby PNC is better than that of the active PNC. PNC-DUP
executes a spontaneous interchange only when a message from a PNC
component MO sends a message indicating that either a fault has occurred on the
active PNC, or a fault has been resolved on the standby PNC such that the state
of health of the active PNC is now lower than that of the standby.
This message will usually indicate the type and location of the failed connectivity
component. A corresponding major or minor alarm is logged by the reporting MO,
stimulating an alarm report.
In the less common situation when the resolution of a fault on the standby renders
it more healthy than a simultaneously faulted active PNC, the message will
indicate the type and location of the improved component.
Once the interchange completes, the failed component will be on the standby
PNC. A demand interchange can be requested in the presence or absence of
standby PNC faults. The following sequence of actions can be observed during a
fault-free interchange:
1. The Expansion Interfaces currently acting as archangels in the PNs are
deactivated as indicated by the amber LEDs going from flashing to on
solid.
2. The EIs in IPSI port networks are interchanged as indicated by the new
standby EI amber LED off and the new active EI amber LED on solid.
3. One by one the EIs in non-IPSI port networks are interchanged as
indicated by new standby EI amber LED turning off and the new active EI
amber LED flashing (2 seconds on, 200 milliseconds off). At this point the
interchange is functionally complete.
4. The SNIs amber LEDs are updated. so that the SNIs on the active SN
have amber LEDs on, while the standby SN's SNIs amber LEDs turn off.
Certain conditions may interfere with the normal execution of the interchange:
1. In a faulted spontaneous interchange it is possible the PN directly affected
by the fault will be the last to interchange.
2. A user directly affected by the single fault instigating a PNC interchange
can experience a momentary outage of voice path connectivity during the
switch.
3. If faults exist on both the standby and active PNC, it is possible to have
some PNs go out of service while others are returned to service.
4. The new standby SNIs amber LED my not be off due to a fault in the line of
communication path to the standby SNIs. In a multi-fault interchange,
LEDs on the new active SNIs may not be on for the same reason.
8-1292 Issue 1 May 2002 555-233-143