The Agent PG
communicates with the Unified Communications Manager cluster through the CTI
Manager. An Agent PG can control agent phones and CTI route points anywhere in
the cluster. The Agent PG registers with the CTI Manager on a Unified
Communications Manager subscriber in the cluster. The CTI Manager accepts all
JTAPI requests from the PG for the cluster. When the PG requests a phone or
route point on another subscriber, the CTI Manager forwards the request to the
other subscriber using the CallManager SDL links.
This section uses
PG to describe any PG that includes the Unified Communications Manager
PIM. The Agent PG can be a Generic PG or a Unified Communications Manager PG.
For example, the following figure uses Generic PGs to connect to the
subscribers. Those Generic PGs are acting as Agent PGs.
design deploys Unified CCE Agent PGs in a redundant configuration, because a PG
only connects to the cluster through a single CTI Manager. If that CTI Manager
fails, the PG cannot communicate with the cluster. A redundant PG provides a
second pathway through a different CTI Manager on a different subscriber in the
The minimum design
for a high-availability cluster is one publisher and two subscribers. If the
primary subscriber fails, the devices rehome to the secondary subscriber and
not to the publisher for the cluster.
Figure 8. High
Availability Design for Unified Communications Manager Cluster
The redundant PG
servers keep in synchronization through a private network that is isolated from
the public network. If the two servers run on different physical machines at
the same site, you can create the private network by connecting an Ethernet
Cross-Over Cable between their private-network NICs. If the two PG servers are
geographically distributed, use a separate WAN connection for the private
network. To avoid a single point of failure in the network, do not use the same
circuits or network gear as for the public network.
Within the Agent PG,
the JTAPI Gateway and Agent PG PIM manage the connectivity to the cluster. The
JTAPI Gateway handles the JTAPI socket connection protocol and messaging
between the PIM and the CTI Manager. The PIM manages the interface between
Unified CCE, the JTAPI Gateway, and the cluster. It requests specific objects
to monitor and handle route requests from the cluster. The PG starts the JTAPI
Gateway and PIM automatically as node-managed processes. The PG monitors the
processes and automatically restarts them if they fail.
installation, download the JTAPI Gateway from the cluster to ensure
compatibility. Whenever you upgrade either the PG or Unified Communications
Manager, remove and reinstall the JTAPI Gateway.
The JTAPI services
from both redundant Agent PGs sign in to the CTI Manager after initialization.
Agent PG Side A signs in to the primary CTI Manager; Agent PG Side B signs in
to the secondary CTI Manager. Only one PG in each pair actively registers and
monitors phones and CTI route points. The redundant PG runs in hot-standby
mode. The redundant PG signs into the secondary CTI Manager only to initialize
the interface and make it available for a failover. This arrangement
significantly decreases the time for the failover.
During system start,
the PG that first connects to the Unified CCE Call Router server and requests
configuration information is the active PG. The Call Router ensures that the PG
side that has the best connection becomes active. The nominal designations of
“Side A” and “Side B” do not affect which PG becomes active. During a PG
failover caused by a private link failure, a weighting mechanism chooses which
PG is active to minimize the impact on the contact center.
The PIM startup
process registers all CTI route points first, which is done at a rate of five
route points per second. For systems with large numbers of CTI route points, it
can take several minutes before the system allows any agents to sign in. You
can reduce this time by distributing the devices over multiple PIM interfaces
to the cluster.
If calls arrive at
the CTI Route Points before the PIM is operational, the calls fail unless you
set up the route points with a recovery number. Place the recovery number in
their Call Forward on Unregistered or Call Forward on Failure setting. For
example, you can set the recovery numbers to the Cisco Unity voicemail system
for the Auto Attendant.
Active PG Shutdowns
Avoid shutting down an active peripheral gateway service in your production environment. This causes a service interruption of a minute or more while the other side connects and activates. The length depends on the size of the configuration and the type of peripheral. For example, the VRU peripheral can take less time. The other side for the VRU might take 30 seconds or less to reactivate.