private void createCacheAndRegion(VM memberVM, int locatorPort) {
    memberVM.invoke("start cache and create region", () -> {
      cache = createCache(locatorPort);
      cache.createRegionFactory(RegionShortcut.REPLICATE)
          .setScope(useDAck ? Scope.DISTRIBUTED_ACK : Scope.DISTRIBUTED_NO_ACK)
          .create(regionName);
    });
  }
This class tests cluster tcp/ip communications both with and without SSL enabled
geode-core/src/upgradeTest/java/org/apache/geode/ClusterCommunicationsDUnitTest.java