IETF RFC 8263 PDF

The Group Domain of Interpretation (GDOI) includes the ability of a Group Controller/Key Server (GCKS) to provide a set of current Group Member (GM) devices with additional security associations (e.g., to rekey expiring security associations). This memo adds the ability of a GCKS to request that the GM devices return an acknowledgement of receipt of its rekey message and specifies the acknowledgement method.