Again, you should refer to the spec. CMP is possible with both local and remote interfaces but it is strongly advised to use only local interfaces as mentioned in section 10.3:
The Bean Provider programming an application that uses container-managed persistence typically avoids calls to the methods of the remote home and remote interfaces in favor of invoking related beans by means of the methods of their local interfaces. Unlike remote method calls, such internal method invocations are made using call-by-reference and commonly do not involve the checking of method permissions.
CMR is only possible with local interfaces as stated in section 9.3:
Entity beans that have container-managed relationships with other entity beans, as described in Chapter 10, �Entity Bean Component Contract for Container-Managed Persistence�, must be accessed in the same local scope as those related beans, and therefore typically provide a local client view. In order to be the target of a container-managed relationship, an entity bean with container-managed persistence must provide a local interface.