By William T. Hanks, Tom Cloonan, Amit Eshet, Jeff Howe, John Ulm, Ian Wheelock, ARRIS
This paper will present a proposal for an extension to the DOCSIS protocol to facilitate the use of a “DOCSIS Multicast Carousel” table which periodically transmits DOCSIS-specific IP multicast forwarding information for each of the currently active multicast group addresses within a MAC Domain Downstream Service Group (MD-DS-SG). The CM may utilize this table of information to rapidly change its own multicast filters (and, if necessary, quickly retune one or more pre-designated downstream channel receivers) in response to subscriber IP video channel change requests without requiring additional control signaling to or from the CMTS. When the subscriber has settled on a program selection for a provisioned timeframe, the final selection and a list of interim selections may be signaled to the CMTS for metrics collection. This proposal is being submitted in an effort to mitigate several issues that have been identified as MSOs and vendors continue to explore IP Video Multicast deployment scenarios. These issues include the large bandwidth requirements that may be needed to support unicast bursts for fast-channel change assistance. The issues also include the high processing and message exchange rates (between CMs and CMTSs) that may be required when large numbers of subscribers initiate simultaneous channel change requests.