Primary Storage

Yes there is a need.  With single initiator/target  zoning it is frequently implemented so that all ports from the same host are zoned to all ports from the same target.  Without masking the node ports in such a zone would be used for internode.  Likewise if replication is used zoning is typically done so that all replication ports from each storage system are in a zone.  Again without masking these ports would then be used for both replication and internode in each cluster. 

so implement  port masking for all clusters.  I hope this helps.  

Just a question by the way: Is there a need for portmasking if you have a correct zoning? For example in a stretched cluster configuration, the intra-cluster communication is separated on a private SAN (virutal or pyhsical). In the public SAN there are only tow types of zoning: Host to SVC and SVC to Storage. And if the zoning follows the rules of a "single-initiator-single-target"-zoning there should be no need for portmasking, or not? Thanks