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 inc lude all of the features of the High Reliab ility option
described a bove. Additionally, the dup licate components of Port Network
Connectivity (PNC) and other comp onents critical to the viab ility of each EPN.
■Switch Node carriers and carrier power supplies (OLSs)
■Switch Node Interface (SNI) circuit p acks
■Switch Node Clock (SNC) circuit p acks (one on each dup licated Switch
Node carrier)
■PPN and EPN Tone-Clock circuit pac ks
■PPN and EPN Expansion Interface circuit packs
■Each EPN contains a TN771D Maintenance/Test circuit pack
■Inter-PN cabling
■DS1 Converter Complexes (circuit p acks, cabling an d DS1 facilities used
to connect remote EPNs)
The entire PNC (whether direct connect or CSS connected ) is duplicat ed as a
whole, forming two identica l sets which each function as a wh ole (A-PNC and
B-PNC). The 2 PNCs operate in an active/standby manner with all i nter-PN calls
set up on both PNCs so that the active c an assume control without disrup tion 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 d uplication strateg ies.