A method and a system. A Medium Access Control (MAC) frame includes an embedded Internet Protocol (IP) frame and a MAC address. The IP frame includes content of a second multimedia program and a second multicast address of the second multimedia program, the MAC address having been resolved from the second multicast address. The second multicast address is determined to be linked to a first multicast address of a first multimedia program of a television channel being played at a user host. The IP frame is forwarded from the MAC frame to an IP layer where the second multicast address is ascertained to be a multicast sub group address of the first multimedia program and is replaced in the IP frame with the first multicast address, after which the IP frame is transmitted to the user host to replace or be inserted into the first multimedia program being played.