Algorithms for Efficient Filtering in Content-Based Multicast (original) (raw)
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Multicasting is a technique for data routing in networks that allows multiple destinations to be addressed simultaneously. The implementation of multicasting requires, however, the solution of difficult combinatorial optimization problems. In this chapter, we discuss combinatorial issues occurring in the implementation of multicast routing, including multicast tree construction, minimization of the total message delay, center-based routing, and multicast message packing.
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IEEE/ACM Transactions on Networking, 1999
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 o f t h e 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 o-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.
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In this thesis we investigate the problem of finding minimum delay applicationlayer multicast trees, such as the trees constructed in overlay networks. It is widely accepted that shortest path trees are not a good solution for this problem since such trees can have nodes with very large degree, termed high load nodes. The load on these nodes makes them a bottleneck in the distribution tree, due to computation load and access link bandwidth constrains.
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We propose a heuristic algorithm for the construction of a heterogeneous multicast distribution tree used for video transmission that satisfies different QoS requests. Our approach assumes an active network where active nodes can filter the video stream. By appropriately choosing the active nodes at which filtering is performed, the proposed algorithm constructs the multicast tree where, for example, the total required bandwidth is minimized. We assume existing multicast routing algorithms to form multicast groups, and the resulting distribution tree is a hierarchical arrangement of those groups. We evaluate the performance of our algorithm and compare it against two other approaches: simulcast and layered encoded transmission. Results show that we can get advantages when network nodes participate in the construction of the heterogenous multicast distribution tree, such as the possibility to set up a larger number of simultaneous multicast sessions.
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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. Multicast groups are usually classi ed as sparse or pervasive groups depending on the physical distribution of group members. They are also classi ed based on the temporal characteristics of group membership into static and dynamic groups. In this paper, we propose two algorithms for constructing multicast trees for multimedia group communication in which the members are sparse and static. The proposed algorithms use a constrained distributed unicast routing algorithm for generating low-cast, bandwidth and delay constrained multicast trees. These algorithms have l o wer message complexity and call setup time due to their nature of iteratively adding paths, rather than edges, to partially constructed trees. We study the performance in terms of call acceptance rate, call setup time, and multicast tree cost of these algorithms through simulation by comparing them with that of a recently proposed algorithm 14 for the same problem. The simulation results indicate that the proposed algorithms provide larger call acceptance rates, lower setup times and comparable tree costs.
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In the paper we introduce a group members arrangement as a new parameter for analyzing multicast routing algorithms finding multicast trees. We also propose a new multicast routing algorithm without constraints. The objective of STA (Switched Trees Algorithm) is to minimize the total cost of the multicast tree using a modification of the classical Prim's algorithm (Pruned Prim's Heuristic) and the SPT (Shortest Path Tree) algorithm that constructs a shortest path tree between a source and each multicast node.
Near-Optimal Allocation of Delay Requirements on Multicast Trees
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Knowing the QoS requirement for each link involved in a multicast connection, such that overall QoS requirement is satisfied, would greatly assist both QoS-based multicast routing and resource reservation processes. In the case of delay, the question of what delay requirements should be imposed on each link of a source-based multicast tree, such that the overall source-to-destination delay and inter-destination delay variation requirements are satisfied at minimum total tree cost, is the focal point of this paper. A major contribution of this paper is the development of a number of heuristic algorithms for (near-)optimal allocation of delay requirements using Genetic Algorithms (GAs). Initial tests, with multicast trees of different sizes (10-and 30-node trees), configurations (in terms of number of destinations and destination distribution), and overall delay requirements, show the ability of the algorithms in providing good solutions within a reasonable amount of time.
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This paper discusses an approach for distributing a large number of multimedia (video) titles to users located at the leaves of a tree network. The proposed approach is to build multicast trees, over which the content files are sent to user disks, followed by delayed local playback of the content. The work concentrates on exact and heuristic methods for an efficient tree packing in several download periods. In order to satisfy all the requests accumulated in a certain time period, we choose to minimize the number of times a multicast tree is split because of capacity constrains. We show that this objective provides lowest link utilization and good convergence both in the integer formulation and in the developed heuristics (of type tabu search, iterated local search, and variable neighborhood search). The model can be also used in a planning setting to answer the question on the maximum user request rate that can be supported by a certain network topology.