Avaya 03-300430 User Manual

In systems with the Critical Reliability option, the following components, which together 
comprise the Port Network Connectivity (PNC), are duplicated:

●

Expansion Interface (EI) TN570 circuit packs in the port networks (PNs)

●

Switch Node Interface (SNI) TN573 circuit packs in switch nodes

●

DS1 Converter (DS1C) TN574 circuit packs for remote PN connections

●

Fiber-optic cables (metallic in certain cases) connecting the above circuit packs

●

DS1 facilities between the DS1Cs

●

Switch Node Clock (SNC) TN572 circuit packs

●

IP Server Interface (IPSI) TN2312AP circuit packs

Although not part of the PNC, Tone-Clock circuit packs are also duplicated in each PN. The 
PNC is available in two different configurations: direct connect, in which each port network is 
connected directly by fiber optic links to each other PN; and Center Stage Switch (CSS) which 
utilizes one or two switch nodes to interconnect the PNs. Direct connect systems can have up to 
two PNs. CSS systems with one switch node can have up to 15 PNs. CSS systems with three 
switch node can have up to 44 PNs. See the following figures.
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).
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, anti-thrashing, 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 will do its 
best to maximize service continuity.
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, error log entries are used to log 
useful information about the occurrence and causes of interchanges. This is done in order to 
facilitate diagnosis of problems, which can then be addressed by using the documentation for 
the individual MO involved.

PNC-DUP

NA

PNC duplication