A method and system of operating a Reliable Transmission Protocol switch node to provide an IPTV multicast is provided. According to an embodiment of the invention, IP packets transporting an encrypted media stream are received from an IPTV Head-end. The media stream contains complete image frames. Unencrypted identifiers identifying packets containing complete image frame data are also received. The received packets are stored in a buffer, and on receipt of a request from a media renderer to provide the IPTV multicast, the packet(s) containing the last complete image frame in the media stream and all subsequent packets are sent to the media renderer.