About HA Through Windows NLB
Note: The information below presents an NLB cluster approach rather than the recommended IP Address Takeover Approach.
Windows Network Load Balancer (NLB) is used to provide high-availability for the following connections:
- The interaction web page on the Knowledge Worker desktop—the custom UC Connector tab—and the UC Connector web port.
- Universal Routing Server (URS) and the UC Connector Custom Server port.
The ports used for both of these connections must be switched over as part of the Window NLB mechanism, in order to ensure that both the Preview Notification method and the custom UC Connector tab continue to operate after a switchover from primary to backup instance of UC Connector.
When configured for HA, the HTTP messages from the UC platform are sent to the Windows NLB cluster—using the virtual IP (VIP) address—and the Windows NLB cluster then delivers this traffic to the individual UC Connector instance, according to its unique IP address.
This figure shows an overview of how HA-enabled UC Connector instances can be deployed. While web communication with the UC platform uses a single Virtual IP address to communicate with UC Connector, Genesys Management and Configuration Layer components and T-Library clients use the unique IP address for communication with the UC Connector and the Local Control Agent (LCA) installed at each UC Connector host.
When a failure occurs, Genesys performs a switchover of the failed primary UC Connector instance to the backup instance. The Genesys Management Layer uses a Windows NLB utility (wlbs.exe or nlb.exe) to enable and disable the web ports used by UC Connector. To start this utility, special control scripts (.bat files) are required. These scripts are triggered when alarm conditions in the UC Connector log events are generated as the UC Connector instances switch modes from primary to backup.