Universal IP Multicast Delivery

Many applications can benefit from ubiquitous availability of multicast delivery. Unfortunately IP multicast coverage on the Internet is spotty at best, limited to individual campuses and a handful of service providers. In response to the slow deployment of IP multicast, a number of end-host multicast mechanisms have been developed. End-host multicast lowers the deployment barrier of multicast technology by moving multicast functionality from routers to hosts. Their performance, however, cannot be as good as that of native IP multicast. We present a framework called Universal Multicast (UM) which integrates end-host multicast with deployed IP multicast islands to achieve ubiquitous multicast delivery. We intend UM to be a general framework that can work with various end-host multicast protocol to build dynamic unicast tunnels to connect IP-multicast enabled “islands.” The design of UM takes full advantage of deployed IP multicast where available and utilizes end-host multicast where needed. An important feature of the UM design is to allow multiple connecting points per IP multicast island. In this paper we show that when an IP multicast island is large in size, having multiple connecting points can significantly speed up packet delivery and reduce traffic concentration.