Maintenance Manual

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Cisco ICM Enterprise Edition Administrator Guide Release 6.0(0)
Chapter 2 Fault Tolerance
Central Controller
Role of the Synchronizers
The Synchronizers play the key role in maintaining synchronized execution
across the two sides of the Central Controller. All input for the CallRouter and any
changes to the Logger must pass through the Synchronizers.
Each time a Synchronizer receives input, it passes that input to its duplicate on the
other side. The two Synchronizers cooperate to ensure that they are both sending
the same input to the Central Controllers on both sides of the system.
Figure 2-4 shows how the Synchronizers combine input messages and send the
messages in the same order to each side of the Central Controller.
Figure 2-4 Role of the Synchronizers
Both CallRouters receive the same input and generate the same output. The
Synchronizers ensure that both sides of the Central Controller return identical
destinations for the same call and write identical data to the databases.
Figure 2-5 further illustrates the Central Controller and its device connections.
Synchronizer Synchronizer
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CallRouter CallRouter
Central Controller
Side A
Central Controller
Side B
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Input Messages
PGs
NICs
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