DOCSIS 3.0 프로토콜에서 멀티캐스트 다운스트림 공유

Abstract

DOCSIS 3.0 introduces channel bonding to create a single virtual channel composed of multiple channels bonded together to deliver greater peak bandwidth to subscriber. When a cable modem joins a multicast session, the other cable modems in the same fiber node receive multicast packets over shared downstream channels. The main drawback is that all forwarded multicast packets with an unknown downstream service identifier (DSID) are discarded in the shared downstream channel, i.e - in accordance with DSID-based filtering and forwarding rules. Here, a new method, to recognize multicast packets with an unknown DSID using a newly proposed DBC-AD (Dynamic Bonding Change-Advertisement) message, is presented. The cable modem termination system (CMTS) forwards a DBC-AD message to other cable modems when a cable modem in the same fiber node joins a multicast session. This message, includes the authorization information such as a DSID, a downstream channel set (DCS), and a multicast session group address, will be stored as a database. This authorization information enables other cable modems to share multicast packet over shared downstream channels after checking the database using the DBC-AD message. The simulation results show that the CM using newly proposed DBC-AD message can reduce a multicast forwarding procedure in the fiber node up to 331%, which applies to broadcasting, IPTV, VoD, and various kinds of the Internet services.