Method and apparatus of multicast service flow processing for head-end cable modem

A multicast service flow processing method for a headend cable modem and an apparatus thereof are provided to divide an input downstream multicast packet per a multicast session and divide service flows corresponding to the divided multicast sessions, thereby configuring information about a corresponding service flow by an inner header. A multicast packet processor(201) divides an input multicast packet per a session and adds and outputs an inner header to the multicast packet. A header processor(204) forms a multicast media access control packet based on the inner header. The header processor transmits the multicast packet to a downstream physical layer by downstream-scheduling the multicast packet.