Dpp System Architecture - Nortel DMS-100 Series Product Manual

1-2 Understanding DPP

DPP System Architecture

The architecture of the DPP is fully redundant (see Figure 1-2). Two
functionally identical units linked by crossover circuits ensure that no critical
AMA data is lost. Under normal operation, the active DPP unit writes
identical copies of data to each of the hard-disk drive units. The inactive DPP
unit, which remains in a warm-standby mode, becomes active if an error
condition is reported on the active unit or if the active side initiates a
processor switch. Internal diagnostics continually monitor the system's
status.
IOC cards provide the interface between the DPP and the rest of the
DMS-100 system. Redundant links, through separate IOCs, exchange AMA
data (Data Stream Interface [DSI] port) and non-AMA data (maintenance
port). Non-AMA data includes log messages, MAP commands, and DPP
program data. If one link fails, the second link automatically assumes the
load previously carried by the failed link.
297-1001-019 Standard 02.01 April 1997