Cisco Unified Contact Center Enterprise Solution Reference ...

Peripheral Gateway Design Considerations
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Cisco Unified Contact Center Enterprise 7.x SRND
Chapter 3 Design Considerations for High Availability
PG side B becomes active and registers all dialed numbers and phones, and call processing
continues.
Agent desktops go back into service and allow full access to state and third-party call control
functions again. However, agents may be left in not-ready state and have to manually go back into
a ready state. (This behavior is configurable.)
For agents that were on active calls at the time of the failover, when they disconnect from all calls,
the agent's desktop functionality is restored to the same state prior to failover, and the IP phone
re-homes to the backup Cisco Unified CallManager subscriber B.
When Cisco Unified CallManager subscriber A recovers, all idle phones and gateways re-home to
it. Active devices will wait until they are idle before re-homing to the primary subscriber.
PG side B remains active, using the CTI Manager on Cisco Unified CallManager subscriber B.
During this failure, any calls in progress at a Unified CCE agent will remain active; however, the
agent will not be able to perform a conference, transfer, or other Cisco Unified CallManager features
until the phone re-homes to an active subscriber. When the call is completed, the phone will re-home
automatically to the backup Cisco Unified CallManager subscriber.
After the failure has recovered, the PG will not fail back to the A side of the duplex pair. All CTI
messaging will be handled using the CTI Manager on Cisco Unified CallManager subscriber B,
which will communicate with Cisco Unified CallManager subscriber A to obtain phone state and
call information.
Figure 3-17 Scenario 1 – Cisco Unified CallManager and CTI Manager Fail
CallManager A
Fails
Agent PG A Agent PG B
M
ICM synchronzation messages
CallManager intra-cluster messages
JTAPI messages
H323 or MGCP messages
SCCP messages
M
IP
CallManager B
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