Cisco Unified Contact Center Enterprise Solution Reference ...

Chapter 3 Design Considerations for High Availability
Figure 3-21 Redundant Unified ICM VRU PGs with Two IP IVR Servers
Public
network
TDM
access
Unified ICM Call Router and Logger
OL-8669-05
T1 lines
Voice
Voice
T1 lines gateway 1
gateway 2 Gatekeepers
V
V
IDF
switch 1
IDF
switch 2
MDF
switch 1
Call control, CTI data,
IP messaging
TDM voice lines
Ethernet lines
Agent
PG A
ICM A
Cisco CallManager
cluster
Publisher
Sub 1 M Sub 2
M M
Agent
PG B
ICM B
ICM central controllers
MDF
switch 2
IP IVR 1
VRU
PG A
IP IVR
group
IP IVR 2
Understanding Failure Recovery
VRU
PG B
Firewall
Corporate
LAN
The Unified ICM Central Controllers or Unified ICM Servers are shown in these diagrams as a single
set of redundant servers. However, depending upon the size of the implementation, they could be
deployed with multiple servers to host the following key software processes:
Unified ICM Call Router
The Unified ICM Call Router is the brain of the system, and it maintains a constant memory image
of the state of all the agents, calls, and events in the system. It performs the call routing in the
system, executing the user-created Unified ICM Routing Scripts and populating the real-time
reporting feeds for the Administrative Workstation. The Call Router software runs in synchronized
execution, with both of the redundant servers running the same memory image of the current state
across the system. They keep this information updated by passing the state events between the
servers on the private LAN connection.
Unified ICM Logger and Database Server
The Unified ICM Logger and Database Server maintain the system database for the configuration
(agent IDs, skill groups, call types, and so forth) and scripting (call flow scripts) as well as the
historical data from call processing. The Loggers receive data from their local Call Router process
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