30-10-2009, 03:32 PM
Abstract
The present network-layer multicast routing protocols build multicast trees based only on hop count and policy. If a tree cannot meet application require- ments, the receivers have no alternative. A general and modular architecture that integrates alternate path routing with the network multicast services is proposed. This enables individual multicast receivers to reroute a multicast tree according to their needs, subject to policy restrictions. Many Internet multicast applications such as teleconferencing and remote diagnosis have Quality-of-Service (QoS) requirements. The requirements can be additive (end-to-end delay), multiplicative (loss rate) or with a bottleneck nature (bandwidth). It is a challenging task to build QoS constrained multicast trees with high performance, high success ratio, low overhead, and low system require- ments. This paper presents a new Enhanced QoS Multicast Routing Protocol (EQMRP) that has very small communication overhead and requires no state out- side the multicast tree. EQMRP achieves the favorable tradeo® between routing performance and overhead by carefully selecting the network sub-graph in which it conducts the search for a path that can support the QoS requirement, and by auto-tuning the selection according to the current network conditions. Its early warning mechanism helps to detect and route around the real bottlenecks in the network, which increases the chance of ¯nding feasible paths for additive QoS re- quirements. EQMRP minimizes the system requirements; it relies only on the local state stored at each router. The routing operations are completely decentralized. The protocol does not require any global network state to be maintained and can operate on top of any unicast routing protocol
[attachment=335]
