private void exchangeRemoteLocators(int port, DistributionConfigImpl config,
      LocatorMembershipListener locatorListener, final String hostnameForClients) {
    RemoteLocatorJoinRequest request = buildRemoteDSJoinRequest(port, config, hostnameForClients);
    String remoteDistributedSystems = config.getRemoteLocators();
    if (remoteDistributedSystems.length() > 0) {
      StringTokenizer remoteLocators = new StringTokenizer(remoteDistributedSystems, ",");
      while (remoteLocators.hasMoreTokens()) {
        DistributionLocatorId remoteLocatorId =
            DistributionLocatorId.unmarshal(remoteLocators.nextToken());
        LocatorDiscovery localDiscovery =
            new LocatorDiscovery(this, remoteLocatorId, request, locatorListener);
        LocatorDiscovery.RemoteLocatorDiscovery remoteLocatorDiscovery =
            localDiscovery.new RemoteLocatorDiscovery();
        _executor.execute(remoteLocatorDiscovery);
      }
    }
  }
For WAN 70 Exchange the locator information across the distributed systems (sites)
geode-wan/src/main/java/org/apache/geode/cache/wan/internal/client/locator/WanLocatorDiscovererImpl.java