DEFINITY Enterprise Communications Server Release 7
Maintenance for R7r
555-230-126
Issue 4
June 1999
Maintenance Object Repair Procedures
9-1304PNC-DUP (PNC Duplication)
9
Antithrashing and PNC Interchanges
Following a spontaneous PNC interchange, subsequent PNC interchanges are
prevented for 5 minutes. This condition is indicated by a "yes" in the Interchange
Disabled? field of the status pnc screen. After 5 minutes, the antithrashing, timer
expires, interchange decisions are re-enabled, and the field displays ‘‘no.’’
Should a catastrophic failure occur on the active PNC during the period when
"Interchange Disabled?" is set to "yes" there will be no spontaneous PNC
interchange.
Demand PNC interchanges also invoke anti-thrashing, but only for a
period of 30 seconds. During antithrashing mode, demand interchanges are also
prevented unless the override option is specified. Use of this option will cause a
service disruption.
Repairs on the Standby PNC Components
!
CAUTION:
If there is a TDM-CLK alarm, system timing may be routed through part of
the standby PNC, and circuit switched data may be affected by the
following repair procedures. This can happen, for example, when a slave
tone/clock circuit pack experiences a loss of signal and switches to receive
timing from the standby EI. In this case TDM-CLK 2305 error will be logged,
and the clock problem should be addressed first, if possible.
To repair PNC components in a duplicated PNC proceed as follows:
1. Most repairs will involve fixing a single fault on the standby PNC. Use
set
pnc lock
or
busy-out pnc
to prevent an interchange into the PNC being
repaired.
2. If a faulty component exists on the currently active PNC, the standby PNC
is more severely faulted. Normally the standby PNC will be fully repaired
first since it is the most severely impaired. To repair the active PNC,
request an interchange via the
reset pnc interchange override-and-lock
command. The
override-and-lock
option ensures that no subsequent
interchange will occur during the repair of the standby PNC. The demand
interchange may not be necessary if the following conditions drive a
spontaneous interchange:
■ The anti-thrashing period from the last interchange has expired.
■ The global refresh from releasing the standby PNC has completed.
The standby PNC SOH is better than the active.
3. At this point, the faulty component will be on the standby PNC, and the
PNCs are locked in their current active/standby state. Busy-out the PNC.
Then fault isolation and component testing procedures for the individual
PNC components can be used just as for a simplex PNC. Replacement of
components will not disrupt operation of the active PNC.
