Scalable Multicast Provisioning in IP Differentiated Services Networks

Ning Wang

Centre for Communication Systems Research (CCSR), University of Surrey, Guildford, UK.

The emergence of point-to-multipoint applications with Quality of Service (QoS) requirements in the Internet has prompted research towards the deployment of multicast communications in Differentiated Services (DiffServ) environments. However, despite many past research efforts, global availability of IP multicast is still a pie in the sky for Internet users, let alone applications with QoS guarantees. One of the key factors that hamper associated progress is scalability, in terms of various types of states associated with routing and signaling in both multicast and QoS. In this thesis we aim at a scalable architectural design of multicast service provisioning for end users with heterogeneous QoS requirements, targeted to the DiffServ environment.

Our architecture consists of three planes: management, control and data plane. First of all, we design and evaluate the Offline Multicast Traffic Engineering (OMTE) building block in the management plane for QoS aware multicast service dimensioning. The main novelty of this scheme is that we shift away from the commonly used Multi-Protocol Label Switching (MPLS) based traffic engineering, and address the bandwidth constrained IP multicast TE directly based on link state routing protocols. With this approach, end-to-end performance can be achieved without MPLS explicit routing that potentially suffers from scalability problems in terms of LSP maintenance and is relatively expensive to deploy.

In the control plane, we propose two different paradigms. QoS aware Source Specific Multicast (QSSM) is designed for dedicated multicast delivery tree construction in different QoS classes, while another overlay scheme, known as Differentiated QoS Multicast (DQM), attempts to build a single hybrid tree that exhibits heterogeneous QoS channels within the network. In both approaches, multicast group addresses are used to encode QoS class information, and the associated benefit is reflected in scalability and backwards compatibility: neither underlying multicast protocols nor existing routers need any extension for carrying and maintaining QoS states within the network.

Finally, envisaging the importance of protecting dimensioned resources from Denial-of-Service (DoS) attacks from malicious hosts, we propose the Multicast Sender Access Control (MSAC) mechanism, which is indispensable in multicast security, but still lacks significant attention from the research community. We focus on bi-directional multicast trees, which is the most vulnerable routing paradigm to DoS attacks. Both intra- and inter-domain control mechanisms are addressed with scalability considerations in mind.

Key words: IP multicast, Source Specific Multicast (SSM), Quality of Service (QoS), Differentiated Services (DiffServ), Traffic engineering (TE), Sender access control, Scalability

PhD Thesis, December 2004.

The full thesis in Acrobat pdf (1.2M) can be made available by contacting the author (N.Wang (at)