Directory Server 11g Release 1 (11.1.1), 6, and 5.2 are compatible with regard to replication configuration, with the following exceptions:
Replication priority is not supported in version 5.2. If you configure replication priority on a 11g Release 1 (11.1.1) master replica, the replication priority will be transferred to consumers running Directory Server 11g Release 1 (11.1.1), but not to any consumers running a previous version of Directory Server.
An unlimited number of masters is not supported on replication topologies that contain Directory Server 5.2 masters. Although Directory Server 11g Release 1 (11.1.1) supports an unlimited number of masters in a replication topology, this number is limited to 4 if your replication topology includes any Directory Server 5.2 master servers.