IP Multicast Over Cable TV Networks

Abstract. When a cable TV network that provides Internet access is connected to multiple ISPs, there are instances where multicast does not work or works inef-ficiently. This paper identifies causes of these problems, and proposes solutions, demonstrating that it is possible to provide efficient multicast with any of the architectures under consideration. In addition, the de facto industry standard for data transmission over cable networks, DOCSISTM, guarantees that a cable com-pany will have the ability to block certain multicast traffic (such as traffic gener-ated by Internet television broadcasters which compete with the cable company’s core business.) This paper describes how an ISP can circumvent this. Under the assumption that there is a significant amount of multicast traffic, we show thatca-ble companies and ISPs would be motivated to provide multicast services in all cases, but there are cases where they are not motivated to choose an efficient ap-proach. Finally, we consider the impact of possible regulation that prohibits cable companies from blocking. In cases where this regulation has any impact, it can increase or decrease the cost of multicast services.