DEFINITY Enterprise Communications Server Release 7
Maintenance for R7r
555-230-126
Issue 4
June 1999
Hardware Configurations
2-18Duplication: Reliability Options
2
Critical Reliability Option
Critical Reliability systems include all of the features of the High Reliability option
described above. Additionally, the duplicate components of Port Network
Connectivity (PNC) and other components critical to the viability of each EPN.
■ Switch Node carriers and carrier power supplies (OLSs)
■ Switch Node Interface (SNI) circuit packs
■ Switch Node Clock (SNC) circuit packs (one on each duplicated Switch
Node carrier)
■ PPN and EPN Tone-Clock circuit packs
■ PPN and EPN Expansion Interface circuit packs
■ Each EPN contains a TN771D Maintenance/Test circuit pack
■ Inter-PN cabling
■ DS1 Converter Complexes (circuit packs, cabling and DS1 facilities used
to connect remote EPNs)
The entire PNC (whether direct connect or CSS connected) is duplicated as a
whole, forming two identical sets which each function as a whole (A-PNC and
B-PNC). The 2 PNCs operate in an active/standby manner with all inter-PN calls
set up on both PNCs so that the active can assume control without disruption of
service. Operation of PNC duplication is described under PNC-DUP in Chapter
9, ‘‘Maintenance Object Repair Procedures’’.
The Tone-Clocks in each EPN operate in an active/standby manner
independently from other duplication strategies.
