When a client application attempts to connect to a busy server, login redirection helps balance the load of the servers by allowing the server to redirect the client connection to less busy servers within the cluster.
At any given time, some servers within a cluster environment are usually more loaded with work than others. The login redirection occurs during the login sequence and the client application does not receive notification that it was redirected. Login redirection is enabled automatically when a client application connects to a server that supports this feature.