The load balancing and failover features work by using a hierarchical view of the hosts associated with the Framework.
The hierarchy of hosts is created by using the Hosts console to group hosts into domains and subdomains, which are representative of your enterprise network structure. This effectively gives them a chain of command, where they always address requests to managers in their immediate subdomain before moving along a branch to another subdomain or parent domain.
To achieve an effective load balancing and failover environment, at least two Framework Manager packages must be deployed across the same Framework. The licensing model is not based on how many managers or agents are deployed, but how many hosts the Framework is deployed on. This means that there are no restrictions on how many Framework Manager packages you can deploy.
The Registry Manager controls a database that records the location and status of each package deployed on each of the hosts within the Framework. A copy of this information is held at each host by the Registry Agent package that is included as part of the agent installation. The distributed information is used to calculate the route to the appropriate manager for requests from any agent registered on the Framework. The structure of the registry data enables each host to determine which Framework Manager on the Framework should be the target of requests, and which Framework Manager to use if there is a failure or withdrawal of the initially selected Framework Manager.