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ATM PNC-DUP (ATM PNC Duplication)
Issue 1 June 2005 587
ATM PNC-DUP (ATM PNC Duplication)
S8700 MC
The PNC-DUP MO tracks the health of the active and standby PNCs, controls planned and
spontaneous interchanges, and manages related functions such as double call refresh and
unrefresh, antithrashing, and so on. The main responsibility of PNC-DUP is to recover the
system to full service in the event of a fault. In the event of multiple faults, PNC-DUP does its
best to maximize service continuity.
Note:
Note: ATM PNC-DUP behaves differently when the system is running the ATM PNC
feature. While not a separate MO, this discussion explains the unique behavior
of PNC-DUP under the ATM PNC feature.
In critical-reliability systems, the following components comprising the port-network connectivity
(PNC), are duplicated:
● ATM-Expansion Interface (ATM-EI) circuit packs in port networks (PNs)
● Fiber-optic cables connecting the above circuit packs to the ATM Switch Interface Modules
● ATM Switch
Although not part of the PNC, Tone-Clock circuit packs are also duplicated in each PN. ATM
PNC systems can have up to 64 PNs.
PNC duplication architecture utilizes an active/standby duplication scheme in which one
complete set of PNC components supports call processing, while the duplicate PNC is held in
reserve. All calls on the active PNC are simultaneously set up, or shadowed, on the standby
PNC in order for it to be capable of instantly assuming active status when necessary, allowing
for interchanges without service disruption (in the case of single faults).
PNC duplication does not introduce any additional types of hardware or hardware faults, and
there are no tests associated with the PNC-DUP MO. Instead, its error log entries contain
useful information about the occurrence and causes of interchanges in order to facilitate
diagnosis of problems, which can then be addressed by using the documentation for the
individual MO involved.
MO Name in Alarm Log Alarm
Level
Initial Command to Run Full Name of MO
PNC-DUP NA status pnc PNC duplication