private Cache createCache(int locatorPort) {
    // if you need to debug SSL communications use this property:
    // System.setProperty("javax.net.debug", "all");
    Properties properties = getDistributedSystemProperties();
    properties.setProperty(LOCATORS, "localhost[" + locatorPort + "]");
    return new CacheFactory(properties).create();
  }
This class tests cluster tcp/ip communications both with and without SSL enabled
geode-core/src/upgradeTest/java/org/apache/geode/ClusterCommunicationsDUnitTest.java