Deployment separtation can be used to introduce better managebility and robustness of a system with e.g. high integration volumes. By setting up a clustered environment where the Managed Servers are grouped by type on the different cluster nodes. E.g. One physical server has two Managed Servers of Main type and another physical server has two Managed Servers of Int type. The benefit here is if the integration server gets highly loaded during specific periods the MainCluster will not be affected as much. Also if the Integration Cluster for some reason needs a restart or maintenance, the user clients will not be affected - only the integrations. In this example there is no actual need for an external load balancer, but if the IntCluster is the most importat and the MainCluster machine is down it can be made availabe using a external load balancer.
Note: For a HA cluster to properly function even when the master node crashed, it is recomended to setup at least two slave nodes (three nodes all together).