Avaya Definity SI, Maintenance Manual, Page: 208 / 2968

Reliability Systems: A Maintenance Aid
555-233-123 6-4 Issue 4 May 2002
Critical Reliability
Critical Reliability systems include all of the features of the High Reliability option
described in the previous section. Additionally, these systems duplicate
components of Port Network Connectivity (PNC) and of other components that
are critical to the viability of each EPN. These components include the following:
■
PPN and EPN Tone-Clock circuit packs
■
PPN and EPN Expansion Interface circuit packs
■
Inter-PN cabling
NOTE:
In Critical Reliability systems, the TN771 Maintenance/Test circuit pack is
required in both the PPN and EPN.
The entire direct-connected fiber is duplicated between each pair of port
networks. Each duplicated fiber pair operates in an active/standby manner with all
inter-PN calls set up on both fibers so that the active SPE can assume control
without disruption of service. Each fiber pair between port networks operates
independently of the other fiber pairs with respect to the active/standby operation,
that is, the A-carrier fiber can be active between the PPN and EPN 1, and the
B-carrier fiber can be active between the PPN and EPN 2.
The Tone-Clocks in each EPN operate in an active/standby manner independently
from other duplication strategies.
Duplicated Hardware
A description of the hardware components used in a High or Critical Reliability
system follows.
SPE Duplication
Each SPE in a high or critical reliability system consists of the following circuit
packs:
■
Processor Circuit Pack (TN2404/TN790)
■
Network Control Circuit Pack (TN777B)
■
Packet Control Circuit Pack (TN778)
NOTE:
There may be zero or one Packet Control circuit pack. However, both
SPEs must have an equal number of circuit packs.