Design of a multicast routing algorithm

科研費報告書収録論文(課題番号:09680388・基盤研究(C)(2)・H9～H10/研究代表者:根元, 義章/情報フィルタリングを用いた大規模情報ネットワークのリアルタイム障害検出方式

Optical Multicast Routing Under Light Splitter Constraints

During the past few years, we have observed the emergence of new applications that use multicast transmission. For a multicast routing algorithm to be applicable in optical networks, it must route data only to group members, optimize and maintain loop-free routes, and concentrate the routes on a subset of network links. For an all-optical switch to play the role of a branching router, it must be equipped with a light splitter. Light splitters are expensive equipments and therefore it will be very expensive to implement splitters on all optical switches. Optical light splitters are only implemented on some optical switches. That limited availability of light splitters raises a new problem when we want to implement multicast protocols in optical network (because usual multicast protocols make the assumption that all nodes have branching capabilities). Another issue is the knowledge of the locations of light splitters in the optical network. Nodes in the network should be able to identify the locations of light splitters scattered in the optical network so it can construct multicast trees. These problems must be resolved by implementing a multicast routing protocol that must take into consideration that not all nodes can be branching node. As a result, a new signaling process must be implemented so that light paths can be created, spanning from source to the group members

Avoidance of multicast incapable branching nodes for multicast routing in WDM networks

In this articlewestudy themulticast routing problem in all-opticalWDMnetworks under the spare light splitting constraint. To implement a multicast session, several light-trees may have to be used due to the limited fanouts of network nodes. Although many multicast routing algorithms have been proposed in order to reduce the total number of wavelength channels used (total cost) for a multicast session, the maximum number of wavelengths required in one fiber link (link stress) and the end-to-end delay are two parameters which are not always taken into consideration. It is known that the shortest path tree (SPT) results in the optimal end-to-end delay, but it can not be employed directly for multicast routing in sparse light splitting WDM networks. Hence, we propose a novel wavelength routing algorithm which tries to avoid the multicast incapable branching nodes (MIBs, branching nodes without splitting capability) in the shortest-path-based multicast tree to diminish the link stress. Good parts of the shortest-path-tree are retained by the algorithm to reduce the end-to-end delay. The algorithm consists of tree steps: (1) aDijkstraPro algorithmwith priority assignment and node adoption is introduced to produce a SPT with up to 38% fewer MIB nodes in the NSF topology and 46% fewerMIB nodes in the USA Longhaul topology, (2) critical articulation and deepest branch heuristics are used to process the MIB nodes, (3) a distance-based light-tree reconnection algorithm is proposed to create the multicast light-trees. Extensive simulations demonstrate the algorithm's efficiency in terms of link stress and end-to-end delay

Position-Based Multicast Routing for Mobile Ad-Hoc Networks

In this paper we present Position-Based Multicast (PBM), a multicast routing algorithm for mobile ad-hoc networks which does neither require the maintenance of a distribution structure (e.g., a tree or a mesh) nor resorts to flooding of data packets. Instead a forwarding node uses information about the positions of the destinations and its own neighbors to determine the next hops that the packet should be forwarded to and is thus very well suited for highly dynamic networks. PBM is a generalization of existing position-based unicast routing protocols such as face-2 or GPSR. The key contributions of PBM are rules for the splitting of multicast packets and a repair strategy for situations where there exists no direct neighbor that makes progress toward one or more destinations. The characteristics of PBM are evaluated in detail by means of simulation

A Multicast Routing Algorithm Using Movement Prediction for Mobile Ad Hoc Networks

Abstract-In mobile ad hoc networks, how to achieve the multicast communication is a challenging task due to the fact that the topology may change frequently and communication links may be broken because of users' mobility. To keep network connectivity, control packets are periodically sent within the system, resulting in high system overhead. To reduce the amount of control packets, a multicast routing algorithm for mobile ad hoc networks is designed in this paper. Utilizing movement prediction to estimate the life time of connections for every node pairs, the algorithm largely reduces the amount of control packets as compared to those using periodical path maintenance. Based on the estimate, a local path search rather than a global one is performed before the breakage of a path to get a backup path. This further lowers the system load. To avoid frequent path breakage, the algorithm chooses the path with the longest life among all possible paths. Using a simulation approach, we investigate the performance of the proposed algorithm through a comparison with an algorithm previously proposed in the literature. Based on the numerical results, we demonstrate that our proposed algorithm performs well

A Multicast Routing Algorithm Using Movement Prediction for Mobile Ad Hoc Networks

Abstract-In mobile ad hoc networks, how to achieve the multicast communication is a challenging task due to the fact that the topology may change frequently and communication links may be broken because of users' mobility. To keep network connectivity, control packets are periodically sent within the system, resulting in high system overhead. To reduce the amount of control packets, a multicast routing algorithm for mobile ad hoc networks is designed in this paper. Utilizing movement prediction to estimate the life time of connections for every node pairs, the algorithm largely reduces the amount of control packets as compared to those using periodical path maintenance. Based on the estimate, a local path search rather than a global one is performed before the breakage of a path to get a backup path. This further lowers the system load. To avoid frequent path breakage, the algorithm chooses the path with the longest life among all possible paths. Using a simulation approach, we investigate the performance of the proposed algorithm through a comparison with an algorithm previously proposed in the literature. Based on the numerical results, we demonstrate that our proposed algorithm performs well

The Edge Group Coloring Problem with Applications to Multicast Switching

This paper introduces a natural generalization of the classical edge coloring problem in graphs that provides a useful abstraction for two well-known problems in multicast switching. We show that the problem is NP-hard and evaluate the performance of several approximation algorithms, both analytically and experimentally. We find that for random $\chi$-colorable graphs, the number of colors used by the best algorithms falls within a small constant factor of $\chi$, where the constant factor is mainly a function of the ratio of the number of outputs to inputs. When this ratio is less than 10, the best algorithms produces solutions that use fewer than $2\chi$ colors. In addition, one of the algorithms studied finds high quality approximate solutions for any graph with high probability, where the probability of a low quality solution is a function only of the random choices made by the algorithm