A relative delay constrained tree for efficient multicast routing
ICCC '02 Proceedings of the 15th international conference on Computer communication
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Motivated by the enriching content of multimedia applications and by the changing requirements and functionality at the user sides, multicast service with different levels of QoS for multiple-point applications has become increasingly demanding. The main intent of this paper is thus to develop and evaluate a set of member join/leave and state update/refresh procedures to provide desired levels of QoS for bi-directional core-based multicast routing with explicit member join and soft state refresh procedures.In our prior work [14] we have (i) devised effective eligibility tests to verify whether or not a new member can join a multicast tree at adequate QoS, while not violating the existing QoS guarantees to other on-tree members; and (ii) determine the minimal possible state needed to conduct eligibility tests, and devise state update procedures accordingly. % In this paper, we lay a more general framework for QoS-driven member join/leave procedure. In particular, we identify the tradeoff between the amount of (updated) state kept at each on-tree router and the degree of collaboration among on-tree routers to conduct the eligibility tests, and develop two member join/leave procedures that range from using the most comprehensive state update procedure (and hence the least degree of collaboration among on-tree routers) to the other extreme. Also, we adopt the soft state concept and devise a soft state refresh/update mechanism that can be readily integrated with the tree maintenance mechanism that already exists in most core-based multicast routing protocols. Finally, we evaluate the proposed framework, in terms of the probability of locating feasible multicast trees, message overheads, and scalability.