User manual

DEFINITY Enterprise Communications Server Release 6
Maintenance for R6vs/si
555-230-127
Issue 1
August 1997
Reliability Systems: A Maintenance Aid
Page 6-3Reliability Options
6
information, see TDM-BUS Maintenance section in Chapter 10, ‘‘Maintenance
Object Repair Procedures’’, and the set tdm command in Chapter 8,
‘‘Maintenance Commands and Trouble-Clearing Aids’’.
High Reliability
High reliability systems duplicate components that are critical to the viability of
the system as a whole to prevent a single failure from dropping all service. These
components include the following:
■ PPN control carrier and carrier power units (OLSs)
■ All SPE circuit packs, including the Processor, Memory, Network
Controller, Processor Interface, Packet Controller, and Duplication
Interface circuit packs
■ PPN Tone Clock circuit pack (EPN Tone-Clocks are not duplicated)
■ TDM buses (described in the previous section)
The duplicated SPEs operate in active/standby fashion. Operation of this
duplication is described in the STBY-SPE and DUPINT MO sections in Chapter
10, ‘‘Maintenance Object Repair Procedures’’. Interchanges of the SPE and of
PPN Tone-Clocks operate independently unless induced by use of the
SPE-select switches.
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
The entire direct-connected fiber connectivity 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 a pair of 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.