Challenges of Integrating ASM and SSM IP Multicast Protocol Architectures

The Source Speciic Multicast (SSM) service model and protocol architecture have recently been proposed as an alternative to the currently deployed Any Source Multicast (ASM) service. SSM attempts to solve many of the deployment problems of ASM including protocol complexity, inter-domain scalability, and security weaknesses. However, the SSM protocol architecture is not radically diierent from that of ASM. This has created opportunities for integrating it into the currently deployed ASM infrastructure. In this paper, we rst describe the ASM and SSM service models and associated protocol architectures, highlighting the relative merits and demerits of each. We then examine the network infrastructure needed to support both of them. Our conclusion is that integration is relatively straightforward in most cases; however there is one case|supporting ASM service over an SSM-only protocol architecture|for which it is diicult to design elegant solutions for an integrated SSM/ASM infrastructure.