Ericsson LBI-38965B - Manual (Page 64)

LBI-38965 FAULT TOLERANCE
C-2
Figure C.1 shows the architecture for a fault tolerant EDACS billing system.
RF
System
Console
Terminal
MIM
(Primary)
MIM
BCU
BCU
C
A
M
C
A
M
AREA
IMC
Console
Terminal To StarGate
Primary
Downlink
Backup
Downlink
(Backup)
Figure C.1 - EDACS Billing Fault Tolerant Architecture
Redundant MIM processors are added to each RF System interface within the IMC. A duplicate CAM is added, which
connects to the redundant BCU/CAL and tape drive.
REDUNDANT OPERATION
The primary and redundant MIM processors operate in a hot standby configuration, i.e., once primary unit failure is
detected, the backup becomes the active processor with minimal disruption to calls in progress. The redundant CAM,
BCU/CAL and tape drive are operated as on-line mirror duplicates. This eliminates any changeover operation; in the event
of failure of one BCU/CAL, or its associated components; the remaining unit continues to operate and process call activity.