If a packet is not matched by any association the IPFE will create a new association by choosing an application server from the Target Set IP List. The choice is based on the Load Balance Algorithm setting.
Regardless of the algorithm, the IPFE will raise a minor alarm of "Out of Balance: High" or "Out of Balance: Low" on an application server whenever it is receiving a statistically high or low amount of traffic in comparison to others within the same Target Set.
If an application server determines that it has reached fully loaded capacity, then it will notify the IPFE not to send it further new connections. This is called Stasis. Application servers may go in and out of Stasis automatically according to the current traffic.
There are two Load Balance Algorithms available:
Hash : load balancing achieved by sending the new connection to a server based on hashing the originating port and IP address.
Hash load balancing will remove an application server from consideration for new connections whenever it is incurring an "Out of Balance: High" alarm. In this way reconnecting connections will always be directed to application servers that are moderately loaded. This feature is independent of Stasis notifications.
Least load : chooses the server with the least load as reported by the application server.
If the loads of two or more of the least-loaded servers are within a configurable percentage of each other, they are considered equally loaded, and the IPFE distributes connections to them in a round-robin fashion.