Sysplex subplexing

A subplex is a subset of a sysplex that consists of all the members in the sysplex that communicate through cross-system coupling facility (XCF) groups with each other, and not with members outside the subset.

Defining multiple subplex scopes within a sysplex can be useful in scenarios where multiple networks with different security or functional attributes are attached to specific systems in the sysplex. For example, consider the scenario where some systems in the sysplex are connected to an internal enterprise network and other systems in the sysplex are connected to external networks that have different security attributes. In this example, you might want to be able to partition the sysplex into two subplexes from a sysplex network function perspective; one that includes the systems connected to the internal network and another for the systems that are connected to the external networks. By defining these separate subplexes, users can still exploit some of the sysplex network functions while preserving the isolation of the networks (that is, without automatically enabling dynamic XCF connectivity across the entire sysplex).