Cisco Unified Contact Center Enterprise Solution Reference ...

Chapter 3 Design Considerations for High Availability
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Unified IP IVR (CRS) Design Considerations
Unified IP IVR (CRS) High Availability Using Cisco Unified CallManager
You can implement Unified IP IVR (CRS) port high availability by using any of the following
call-forward features in Cisco Unified CallManager:
Forward Busy — forwards calls to another port or route point when Cisco Unified CallManager
detects that the port is busy. This feature can be used to forward calls to another CTI port when a
Unified IP IVR (CRS) CTI port is busy due to a Unified IP IVR (CRS) application problem, such as
running out of available CTI ports.
Forward No Answer — forwards calls to another port or route point when Cisco Unified
CallManager detects that a port has not picked up a call within the timeout period set in
Cisco Unified CallManager. This feature can be used to forward calls to another CTI port when a
Unified IP IVR (CRS) CTI port is not answering due to a Unified IP IVR (CRS) application
problem.
Forward on Failure — forwards calls to another port or route point when Cisco Unified CallManager
detects a port failure caused by an application error. This feature can be used to forward calls to
another CTI port when a Unified IP IVR (CRS) CTI port is busy due to a Cisco Unified CallManager
application error.
Note When using the call forwarding features to implement high availability of Unified IP IVR (CRS) ports,
avoid creating a loop in the event that all the Unified IP IVR (CRS) servers are unavailable. Basically,
do not establish a path back to the first CTI port that initiated the call forwarding.
Unified IP IVR (CRS) High Availability Using Unified ICM
You can implement Unified IP IVR (CRS) high availability through Unified ICM scripts. You can
prevent calls from queuing to an inactive Unified IP IVR (CRS) by using the Unified ICM scripts to
check the Unified IP IVR (CRS) Peripheral Status before sending the calls to it. For example, you can
program a Unified ICM script to check if the Unified IP IVR (CRS) is active by using an IF node or by
configuring a Translation Route to the Voice Response Unit (VRU) node (by using the consider if field)
to select the Unified IP IVR (CRS) with the most idle ports to distribute the calls evenly on a call-by-call
basis. This method can be modified to load-balance ports across multiple Unified IP IVR (CRSs), and it
can address all of the Unified IP IVR (CRSs) on the cluster in the same Translation Route or Send to
VRU node.
Note All calls at the Unified IP IVR (CRS) are dropped if the Unified IP IVR (CRS) server itself fails. It is
important to distribute calls across multiple Unified IP IVR (CRS) servers to minimize the impact of
such a failure. In Unified IP IVR Release 4.0(x), there is a default script to handle cases where the
Unified IP IVR (CRS) loses the link to the IVR Peripheral Gateway, so that the calls are not lost.
Cisco Unified Contact Center Enterprise 7.x SRND
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