Cisco Unified Contact Center Enterprise Solution Reference ...

Peripheral Gateway Design Considerations
3-24
Cisco Unified Contact Center Enterprise 7.x SRND
Chapter 3 Design Considerations for High Availability
CallManager CTI Manager, and it is specific for the version of Cisco Unified CallManager. This
software module must be downloaded from Cisco Unified CallManager when the PG is initially set up
to ensure specific version compatibility.
The Agent PG Peripheral Interface Manager (PIM) is also a node-managed process and is monitored for
unexpected failures and automatically restarted. This process manages the higher-level interface
between the Unified ICM and the Cisco Unified CallManager cluster, requesting specific objects to
monitor and handling route requests from the Cisco Unified CallManager cluster.
In a duplex Agent PG environment, both JTAPI services from both Agent PG sides log into the CTI
Manager upon initialization. Cisco Unified CallManager PG side A logs into the primary CTI Manager,
while PG side B logs into the secondary CTI Manager. However, only the active side of the Cisco Unified
CallManager PG registers monitors for phones and CTI route points. The duplex Agent PG pair works
in hot-standby mode, with only the active PG side PIM communicating with the Cisco Unified
CallManager cluster. The standby side logs into the secondary CTI Manager only to initialize the
interface and make it available for a failover. The registration and initialization services of the
Cisco Unified CallManager devices take a significant amount of time, and having the CTI Manager
available significantly decreases the time for failover.
In duplex PG operation, the side that goes active is the PG side that is first able to connect to the Unified
ICM Call Router Server and request configuration information. It is not deterministic based upon the
side-A or side-B designation of the PG device, but it depends only upon the ability of the PG to connect
to the Call Router, and it ensures that only the PG side that has the best connection to the Call Router
will attempt to go active.
The startup process of the PIM requires that all of the CTI route points be registered first, which is done
at a rate of 5 route points per second. For systems with a lot of CTI route points (for example, 1000),
this process can take as long as 3 minutes to complete before the system will allow any of the agents to
log in. This time can be reduced by distributing the devices over multiple PIM interfaces to the
Cisco Unified CallManager cluster.
Cisco Unified CallManager will accept multiple PG/PIM connections on a single cluster, which allows
Unified CCE to distribute different types of registrations across multiple connections. For example, one
PIM could be configured to log in as JTAPIuser1 and have only the CTI route points associated with it,
while a second PIM could be logged in as JTAPIuser2 and have the agent IP phones registered to it. This
arrangement would allow agents to log in faster at startup, without having to wait for the dialed numbers
to be registered with CTI Manager first.
Cisco Unified CallManager Failure Scenarios
A fully redundant Unified CCE system contains no single points of failure. However, there are scenarios
where a combination of multiple failures can reduce Unified CCE system functionality and availability.
Also, if a component of the Unified CCE solution does not itself support redundancy and failover,
existing calls on that component will be dropped. The following failure scenarios have the most impact
on high availability, and Cisco Unified CallManager Peripheral Interface Managers (PIMs) cannot
activate if either of the following failure scenarios occurs (see Figure 3-16):
Agent PG/PIM side A and the secondary CTI Manager that services the PG/PIM on side B both fail.
Agent PG/PIM side B and the primary CTI Manager that services the PG/PIM on side A both fail.
In either of these cases, the Unified ICM will not be able to communicate with the Cisco Unified
CallManager cluster.
OL-8669-05