Yes, you are on the right track here. Since the instances are on two different hosts, fronting it with a LB would ensure that JSession cookies are properly encoded and available to the surviving instance when instance failure occurs and the requests are failed over to the surviving instance.
But before going in for LB setup and configuration, its better to first ensure that basic multicast works between the two instances. (used for group member discovery, health monitoring and for finding sessions )
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