Providing Multicast Communication in a Differentiated Services Network Using Limited Branching Techniques

The differentiated services (DS) paradigm has emerged as a scalable approach to provide QoS for unicast communication in the Internet. Utilizing the DS to provide QoS for multicast poses several challenges because of the multi-point aspect, dynamic group membership, and heterogeneous receiver resource requirements of multicast. Existing proposals to accomplish this goal either require extra per packet overhead or changing multicast routing tables. This paper proposes an alternate architecture called M-DS (multicast-DS), utilizing two inter-operable limited branching techniques, edgerouter branching and limited-core branching, as appropriate within each DS domain. Our focus is on defining the signaling protocols for each technique, one for resource allocation on membership discovery and another for resource deallocation on membership termination in subnetworks. Signaling sets up state in each DS domain so that the data can flow through them as it would in the case of the unicast DS. M-DS preserves the DS scalability, does not incur any per packet overhead due to extra headers in data packets, and routes packets using the IP multicast routing tables that are already set up in individual domains, albeit by enhancing the router functionality. We evaluate the performance (signaling overhead and extra bandwidth required) of our architecture and show that it is practical to include it in the current DS framework. ∗This work is supported by the AFOSR MURI grant F49620-00-1-0327, NSF grant ANI-9973115, and by a research grant from Bellsouth.