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

Required Density of Multicast Capable Optical Cross Connects to Assure Efficient Multicasting

International audienceMany algorithms are developed to deploy multicast in optical networks. Those algorithms are designed to resolve the main issue of multicasting in optical networks, which is not all optical cross-connect in the network are capable to split an incoming light signal to more than one output interface. Some of those algorithms are based on additional signaling exchanged to generate the appropriate multicast trees, some use rerouting to source, and some generate multiple multicast trees for the same multicast group. The performance of those algorithms depends basically on the number and location of multicast capable cross-connects. A multicast capable cross-connect (MCOXC) is an optical node equipped with light splitter that allows splitting an incoming light signal to any two or more output interfaces. This paper studies how many nodes in optical networks must be equipped with light splitters to assure good performance of multicast algorithms in sparse splitting networks. This depends basically on the topology in terms of number of nodes, the average node degree and the variation of the node degree distribution over the network nodes. The more the variation of the node degree is, the more splitters are required

Multicast sur les réseaux optiques

Optical networks had been an important area of improvement in terms of its deployment as a core of the backbone of the international communication network. Fiber optics show a big evolution in terms of link capacity and speed compared to any other type of cables. Moreover, multicasting over IP networks had matured in the past years and this was because of the reduction in traffic which resulted when multiple clients requested to receive the same information from the same source. To support multicasting in optical networks, optical nodes have to branch one incoming light wave to more than one output port. Optical nodes must be equipped with light splitters that split one light wave to more than one output. Due to its complex design, a light splitter is very expensive equipment, thus, equipping all optical nodes with splitters will increase the cost of the optical network setup. This leads to a consensus that not all optical nodes on the network will possess this splitting capability. This document is divided into three main parts. In the first part, a brief description of multicast routing and optical networks is given respectively. Then an introduction of multicasting over optical networks is given. The main issue is that not all nodes in the network are multicast capable. The second part provides propositions to resolve network design faces of this main issue. This part studies the optimal density, placement and capabilities of those splitters in the network. Each of these propositions is simulated to evaluate its performance and criticize its efficiency. The last part of this document, describes a new signaling mechanism that modify the process of generating the multicast trees because of the light splitting limitation. This rerouting signaling mechanism depends on the number of the light splitters compared to the size of the network. At the end, conclusions for all the work done in the three parts are summarized, and a prospective is given. Next steps are identified to benefit of work done in real network design and development.Les réseaux optiques sont un domaine important de développement en termes de déploiement comme coeur de la dorsale du réseau de communication international. Les fibres optiques montrent une rapide évolution en termes de capacité et de vitesse de lien comparées à n'importe quel autre type de supports. Par ailleurs, le multicast sur réseaux IP a mûri ces dernières années. Il en résulte une grande réduction de trafic lorsque plusieurs clients demandent de recevoir la même information de la même source. Pour permettre le multicast dans les réseaux optiques, les noeuds optiques doivent diviser une onde lumineuse entrante et la commuter vers plusieurs ports de sortie. Les noeuds optiques doivent être équipés des répartiteurs de lumière ("light splitters") qui splitent une onde lumineuse vers plus d'une sortie. En raison de sa conception complexe, un répartiteur de lumière est un équipement très coûteux, de ce fait, équiper tous les noeuds optiques de répartiteurs peut augmenter inconsidérément le coût d'installation du réseau optique. Ceci mène à un consensus : tous les noeuds optiques du réseau ne sont pas capables de spliter la lumière. Le document est divisé en trois parties principales. Dans la première partie, une description du routage multicast et des réseaux optiques sont données successivement. Ensuite, nous introduisons le multicast sur les réseaux optiques. Le problème général est que tous les noeuds optiques dans le réseau ne sont pas capables de spliter. La deuxième partie propose plusieurs solutions pour résoudre ce problème général. Cette partie étudie la densité, le placement et les capacités de ces répartiteurs optiques dans le réseau. Chacune de ces solutions est simulée pour évaluer ses performances et pour analyser son efficacité. La dernière partie décrit un nouveau mécanisme de signalisation qui modifie le processus de construction d'un arbre multicast en raison de l'absence (ou la présence) d'un répartiteur optique dans les noeuds du réseau optique chargés de supporter l'arbre optique. Ce mécanisme de signalisation par reroutage dépend du nombre de répartiteurs de lumière comparé à la taille du réseau. En conclusion, le travail effectué dans les trois parties est récapitulé et une prospective est donnée. De prochaines étapes sont identifiées pour pleinement bénéficier de notre travail fait dans la conception et développement des futurs réseaux optiques.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Effect of Splitting Factor on Multicast Trees in Optical Networks

Abstract: Enhanced optical switches structure can now handle multicast routing in the optical layer. For an optical node to be able to do branching in the physical layer, it must be equipped with a light splitter. Light splitters are expensive equipment. A lot of work had been done in order to reduce the cost of implementing splitters within the network. Moreover, the internal structure of a splitter is enhanced to reduce its cost, and the power loss resulted of multiple splitting. Efficient placement of splitters in the network leads to a reduction in the cost of the network design, and the cost of the generated trees. The splitting capability of each splitter plays an important role on how much branching can be done on the optical node. Also, the splitting capability affects the power loss done on each branching node, and consequently the final power received by each member. This paper studies the effect of the splitting factor on the cost of the generated trees and the value of the power received by each of the multicast group members. the reduction of power done on each splitting node on the other hand. This paper is organized as follows: in section II, a brief description of the architecture of a multicast capable node is presented. In section III, related work on how to enhance the structure of those splitters to reduce the cost, and increase the network performance. Also their placement in the network is presented. In section IV, a comparison between splitting capabilities versus number of splitters is done. In the last section, network performance is evaluated, and results of the evaluation show that reducing the splitting capability and increasing the number of splitters enhance the multicast routing from one side, and reduce the numbers of amplifiers needed from the other side. I

Efficient Placement of Light Splitters for Heterogeneous Multicast Traffic in Optical Networks

International audienceWhen multicasting in optical networks is implemented within the switching control plane, it combines the efficiency of multicast tree along with high speed and low delay of optical communications. Multicast nodes must be equipped with light splitters. Light splitters are expensive equipment. Therefore, a limited number of optical nodes will have this splitting capability. A good placement of optical splitters can increase the efficiency of the multicast signaling and routing techniques on one hand, and reduce the number of those splitters on the other hand. This leads to faster multicast trees setting up, lower data transmission delays, and less traffic on the network links; thus saving of optical links capacity for other multicast and unicast transmissions. In order to achieve efficient multicasting in optical network, we propose to take into account network characteristics (link capacity and node degree) when placing the optical splitters. The benefits of the smart placement of light splitters will be clearly shown in heterogeneous optical networks, where multicast traffic is not uniformly distributed over the network, and optical links connecting different nodes in the network have different characteristics

Power Fairness for Multicast Traffic in Optical Networks with Adaptive Light Splitters

Abstract: To perform data multicasting in the optical layer, optical nodes must be equipped with light splitters. Light splitters can split one light wave to more than one node output. A lot of work had been done in order to enhance the structure of the light splitter in a way to reduce its cost and enhance its performance in terms of the power loss resulted of multiple splitting. To guarantee the fairness of power received by different members of a same multicast group, the use of adaptive light splitters is required. Adaptive light splitters allow splitting an incoming light signal into two or more node output with the ability of varying the individual power of each output signal. This paper studies the benefits of using adaptive splitters on the value of the power received by each of the multicast group members in a way to assure fairness among all members. I