This post explain the network communication done through all facets of DFSR operation and administration. Even if you don’t care about firewalls and ports, this should shed some light on DFSR networking in general, and may save you skull sweat someday. DFSR and RPC: Plenty of Windows components support hard-coding to exclusive ports, and at a glance, DFSR is no exception. By running the DFSRDIAG STATICRPC command against the DFSR servers you force them to listen on whatever port you like for file replication. Many Windows RPC applications use the Endpoint Mapper (EPM) component for these types of client-server operations.
Full Article: DS Blog