In this paper, we introduce Relayed Multicast Control Protocol (RMCP). The RMCP has been designed for realizing and managing the relayed multicast. Relayed multicast, as known as Overlay Multicasting or Application-level Multicasting, is a data delivery scheme for one-to-many multicast application, in which one or more intermediate Multicast Agents are employed for relaying application data from a sender to many receivers along a tree hierarchy. In RMCP, a special-purpose entity, named Session Manager, is used to manage the overall control operations. RMCP is designed to ensure that the multicast applications and services can be provided along with the associated relayed data transport schemes over current Internet environments in which IP multicast has not completely been deployed.