Cisco Unified Contact Center Enterprise Solution Reference ...

Understanding Failure Recovery
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Cisco Unified Contact Center Enterprise 7.x SRND
Chapter 3 Design Considerations for High Availability
Any new calls that come into the disabled side will not be routed by the Unified CCE, but they can
be redirected or handled using standard Cisco Unified CallManager redirect on failure for their CTI
route points.
Agents will be impacted as noted above if their IP phones are registered to the side of the
Cisco Unified CallManager cluster opposite the location of their active Peripheral Gateway and CTI
OS Server connection. Only agents that were active on the surviving side of the Peripheral Gateway
with phones registered locally to that site will not be impacted.
At this point, the Call Router and Cisco Unified CallManager Peripheral Gateway will run in simplex
mode, and the system will accept new calls from only the surviving side for Unified CCE call treatment.
The Unified IP IVR/Unified CVP functionality will also be limited to the surviving side as well.
Scenario 4: Unified MA Location WAN (Visible Network) Fails
The Unified CCE design model for clustering over the WAN assumes the Unified CCE agents are
remotely located at multiple sites connected by the visible WAN. Each agent location requires WAN
connectivity to both of the data center locations across the visible WAN where the Cisco Unified
CallManager and Unified ICM components are located. These connections should be isolated and
provide for redundancy as well as making use of basic SRST functionality in the event of a complete
network failure, so that the remote site would still have basic dial tone service to make emergency (911)
calls.
If side A of the WAN at the Unified MA location fails, the following conditions apply:
Any IP phones that are homed to the side-A Cisco Unified CallManager subscribers will
automatically re-home to the side-B subscribers (provide the redundancy group is configured).
Agent desktops that are connected to the CTI OS or Cisco Agent Desktop server at that site will
automatically realign to the redundant CTI OS server at the remote site. (Agent desktops will be
disabled during the realignment process.)
If both sides of the WAN at the Unified MA location fail, the following conditions apply:
The local voice gateway will detect the failure of the communications path to the Cisco Unified
CallManager cluster and will go into SRST mode to provide local dial-tone functionality.
The agent desktop will detect the loss of connectivity to the CTI OS Server (or Cisco Agent Desktop
Server) and automatically log the agent out of the system. While the IP phones are in SRST mode,
they will not be able to function as Unified CCE agents.
Understanding Failure Recovery
This section analyzes the failover recovery of each individual part (products and subcomponents inside
each product) of the Unified CCE solution.
Cisco Unified CallManager Service
In larger deployments, it is possible that the Cisco Unified CallManager to which the agent phones are
registered will not be running the CTI Manager service that communicates with the Cisco Unified
CallManager Peripheral Gateway for Unified CCE. When an active Cisco Unified CallManager (call
processing) service fails, all the devices registered to it are reported “out of service” by the CTI Manager
service locally and to any external client, such as the Peripheral Gateway on a different subscriber CTI
Manager service.
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