Multicast services have been increasingly used in large scale continuous media applications. The quality-of-service (QoS) requirements of these continuous media applications prompt the necessity for QoS-driven, constraint-based multicast routing. This article provides a comprehensive overview of existing multicast routing algorithms, protocols, and their QoS extension. In particular, we classify multicast routing problems according to their optimization functions and performance constraints, present basic routing algorithms in each problem class, and discuss their strengths and weakness. We also categorize existing multicast routing protocols, outline the issues and challenges in providing QoS in multicast routing, and point out possible future research directions.

The increasing interest in distributed applications like multimedia and collaborative work calls for efficient means to support multicast communication. A fundamental issue in multicast communication is route selection, usually based on trees. We present a destinationdriven algorithm that optimizes for applications, such as group video- or tele-conferencing, that require multicast trees with low total cost. The destination-driven algorithm uses a greedy strategy based on shortest-path trees and minimal spanning trees but biases routes through destinations. The performance of the algorithm is analyzed through extensive simulation and compared with several Steiner tree heuristics and the popular shortest-path tree (SPT) method. The algorithm is found to produce trees with significantly lower overall cost than the SPT while maintaining reasonable per-destination performance. Its performance is also shown to compare well with other well-known Steiner heuristics. Moreover, the algorithm do...

In multicasting routing, the main objective is to send data from one or more source to multiple destinations, while at the same time minimizing the usage of resources. Examples of resources which can be minimized include bandwidth, time and connection costs. In this paper we survey applications of combinatorial optimization to multicast routing. We discuss the most important problems considered in this area, as well as their models. Algorithms for each of the main problems are also presented.

The paper addresses the issue of minimizing the number of nodes involved in the routing over a multicast tree and in the maintenance of such a tree in a datagram network. It presents a scheme where the tree routing and maintenance burden is laid only upon the source node and the destination nodes associated with the multicast tree. The main concept behind this scheme is to view each multicast tree as a collection of unicast paths, and to locate only the multicast source and destination nodes on the junctions of their multicast tree. The paper shows that despite of this restriction, the cost of the created multicast trees is not necessarily higher than the cost of the trees created by other algorithms that do not impose the restriction and therefore require all the nodes along the data path of a tree to participate in the routing over the tree and in the maintenance of the tree.

With the proliferation of multimedia group applications, the construction of multicast trees satisfying Quality of Service (QoS) requirements is becoming a problem of prime importance. Many of the multicast applications (such as video broadcasts and teleconferencing) require the network to support dynamic multicast sessions wherein the membership of the multicast group changes with time. In this paper, we propose and evaluate an algorithm called CRCDM (Controlled Rearrangement for Constrained Dynamic Multicasting) for on-line update of multicast trees to adjust to changes in group membership. The CRCDM algorithm is based on a concept called Quality Factor (QF) that represents the usefulness of a portion of the multicast tree to the overall multicast session. When the usefulness of a particular region of the tree drops below a threshold, a rearrangement technique is used to suitably modify the tree. Our algorithm aims to satisfy the delay-constraints of all current group members, at the same time minimizing the cost of the constructed tree. We compare the performance of our algorithm, by simulation, with that of an off-line Steiner heuristic; with ARIES [2], a recently published algorithm for on-line update of unconstrained trees; and with the algorithm proposed in [10] for on-line update of delay-constrained trees. The simulation results indicate that our algorithm provides excellent cost-competitiveness that is better than that provided by the algorithm described in [10], minimizes changes in the multicast tree after each update, and performs favorably even when compared with the unconstrained ARIES heuristic. Keywords: Multicast routing, On-line Steiner problem, Dynamic multicast groups, Rearrangement algorithm, QoS, Group communication This work was...

In the age of multimedia and high-sl)eed networks', multicast is one of the mechanisms by which the power of the Internet can be further harnessed in an efficient manner. When more than one receiver is interested in receiving a transmission from a single or a set of senders, multicast is the most efficient and viable mechanism. In the protocol stack of the network, multicast is best implemented in the network layer in the form of a multicast routing protocol to select the best path for the transmission. The other layers' of the protocol stack provide additional features for multicast.

With the proliferation of multimedia group applications, the construction of multicast trees satisfying Quality of Service (QoS) requirements is becoming a problem of prime importance. Many of the multicast applications (such as video broadcasts and teleconferencing) require the network to support dynamic multicast sessions wherein the membership of the multicast group changes with time.

Many new distributed multimedia applications involve dynamic multiple participants, have stringent end-to-end delay requirement and consume large amount of network resources. In this paper, we propose a distributed delay-constrained dynamic multicast routing algorithm (DCDMR) to support these applications. DCDMR scales well because the source of the multicast tree needs only limited computation or may even not be involved in the route computation. When group membership changes, the existing multicast tree is perturbed as little as possible and the average resulting tree cost is very satisfactory. 1 Introduction Many new distributed real-time applications of computer networks such as distance education and videoconferencing involve multiple participants, have stringent end-to-end delay requirement and consume large amount of network resources. In order to support these new applications efficiently, multicast routing algorithms computing least cost multicast trees that satisfy a given e...

In wireless sensor networks, efficiently disseminating data from a dynamic source to multiple mobile sinks is important for applications such as mobile target detection and tracking. The tree-based multicasting scheme can be used. However, due to the short communication range of each sensor node and the frequent movement of sources and sinks, a sink may fail to receive data due to broken paths, and the tree should be frequently reconfigured to reconnect sources and sinks. To address the problem, we propose a dynamic proxy tree-based framework in this paper. A big challenge in implementing the framework is how to efficiently reconfigure the proxy tree as sources and sinks change. We model the problem as on-line constructing a minimum Steiner tree in an Euclidean plane, and propose centralized schemes to solve it. Considering the strict energy constraints in wireless sensor networks, we further propose two distributed on-line schemes, a shortest path-based (SP) scheme and a spanning range-based (SR) scheme. Extensive simulations are conducted to evaluate the schemes. The results show that the distributed schemes have similar performance as the centralized ones, and among the distributed schemes, SR outperforms SP.

Abstract. In this paper, we propose a multi-objective traffic engineering scheme using different distribution trees to dynamic multicast groups (i.e., in which egress nodes can change during the connection’s lifetime). If a multicast tree is recomputed from scratch, it may consume a considerable amount of CPU time and all communication using the multicast tree will be temporarily interrupted. To alleviate these drawbacks we propose an optimization model (dynamic model MHDB-D) that makes use of a previously computed multicast tree (static model MHDB-S) in order to add new egress nodes. Using these two models, our aim is to combine into a single aggregated metric, the following weighting objectives: maximum link utilization, hop count, total bandwidth consumption and total end-to-end delay. Moreover, our proposal solves the traffic split ratio for multiple trees. The problem is NP-hard, therefore, two novel multicast multi-objective dynamic routing algorithms (MMR-S and MMR-D) are proposed for optimizing the different objectives. We compare the dynamic multicast routing model (MHDB-D) with the static model (MHDB-S) and the algorithm proposed (MMR-D). The proposed approaches can be applied in MPLS networks by allowing explicit routes to be established in multicast events. The main contributions of this paper are the optimization models for static and dynamic multicast routing; and the heuristic algorithms proposed. 1.