Avaya S8700 Maintenance Manual page 2015

For multi-connect configurations

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PNC-DUP (PNC Duplication)

In any multifault situation, rely on status pnc to determine which is the active

PNC duplication informs Timing Synchronization maintenance when a PNC

interchange has been completed and indicates which PNC is active. This will

cause Synchronization to audit and insure that the primary source for

synchronization of Tone-Clocks in each PN is supplied by a path associated with

the active PNC.

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 form. 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

Repairs on the Standby PNC Components

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

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

Issue 1 May 2002

Troubleshooting