Multicast Grooming Research Articles

Hybrid graph-based multicast traffic grooming in metro networks with quality-of-transmission considerations

This paper investigates the problem of multicast traffic grooming in optical networks utilizing a novel grooming approach that is based on the routing/grooming of multicast calls on hybrid graphs (HGs). HGs are constructed dynamically upon the arrival of each multicast call, in such a way that they consist of both the available physical links and the logical links with available capacity. Several schemes were developed for the construction of the HGs, namely the minimum free capacity light-tree first, the maximum free capacity light-tree first, the maximum overlapping light-tree first, the least-used light-tree first, and the most-used light-tree first scheme. Also, a novel hybrid Steiner tree heuristic for routing/grooming on the HGs is presented. The proposed grooming approach exhibits improved performance in terms of blocking probability compared to existing multicast grooming approaches that route/groom multicast calls by considering physical and logical links separately. Furthermore, the physical layer impairments were also considered during the provisioning phase of the newly established light-trees on the HG, in which case the proposed schemes also exhibit improved performance compared to other grooming approaches.

Green multicast grooming based on cross-shared protection in optical WDM networks

Currently, multicast survivability in optical network obtains more attention. This paper focuses on the field of multicast grooming shared protection in green optical network and designs a novel auxiliary graph and a shared matrix to address the survivable multicast resource consumption. This paper also proposes a new heuristic called Green Multicast Grooming algorithm based on spanning path Cross-Shared protection (GMG-CSP), in which network reliability, energy efficiency and resource utilization are jointly considered. Simulation results testify that, compared to other algorithms, the proposed GMG-CSP not only has lower blocking probability and higher bandwidth utilization ratio, but also saves more energy.

A new green multicast grooming protection algorithm in WDM optical networks

Since optical network carries a lot of traffic, survivability is very important to ensure the service continuity against network failures. Recently, multicast services become more popular to meet the huge multimedia demand in network, so that multicast survivability in optical network has got more attention. However, multicast survivability may lead to more energy consumption due to more redundant backup resources allocated. Since greening network is particularly important with the energy crisis keeping growing, green multicast survivability in optical network is a challenging issue. This paper focuses on the green multicast grooming protection problem in optical network and designs two auxiliary graphs that includes a virtual topology graph and an integrated graph to address the survivable multicast grooming, routing and wavelength assignment. Based on the auxiliary graphs, this paper proposes an efficient heuristic called green multicast grooming algorithm based on spanning path dedicated protection (GMG-SPDP), in which the network reliability and the energy efficiency are jointly taken into account. Simulation results show that, compared to other algorithms, the proposed GMG-SPDP not only has lower blocking probability and higher bandwidth utilization ratio, but also saves more energy.

Multicast Traffic Grooming in Tap-and-Continue WDM Mesh Networks

Multicast applications are expected to be major drivers of Internet traffic growth. As most multicast connections require much lower bandwidth than the capacity offered by a wavelength, multicast traffic grooming is needed to efficiently use network resources. Recent research on multicast grooming has focused on light-trees because of their natural advantage for multicast traffic. However, using light-trees may lead to some serious negative side effects because of light splitting. In this paper, we investigate the multicast traffic grooming problem in tap-and-continue (TaC) networks, where a node can tap a small amount of incoming optical power for the local station while forwarding the remainder to an output. We first propose a simple and efficient node architecture with the TaC mechanism. We use this in an integer linear programming (ILP) formulation with the objective of minimizing the network cost in terms of the number of higher layer electronic ports and the number of wavelengths used. Since the ILP is not scalable, two heuristic algorithms, multicast trail grooming (MTG) and multiple destination trail-based grooming (MDTG), are proposed. Using the ILP, we show that having more costly nodes with multicast capability does not improve the performance significantly. The solutions obtained by MTG and MDTG are close to the ILP optimal solution. MTG and MDTG are shown to work efficiently for typical network topologies such as NSFNET, with MTG showing better performance than MDTG.

Multicast multi-granular grooming based on integrated auxiliary grooming graph in optical networks

In order to improve the bandwidth utilization efficiency and reduce the blocking probability for multicast requests in optical networks, the multicast traffic grooming approach was proposed to groom a lot of low-speed traffic to a few of high-speed light-trees. At the same time, in order to save the ports and the cost of optical cross-connect, the multicast waveband grooming approach was proposed to groom multiple light-trees to a few of waveband tunnels. However, the existing approaches all did not consider the joint performances of improving bandwidth utilization efficiency, reducing blocking probability and saving ports for multicast requests. Therefore, in this article, we propose a new multicast multi-granular grooming approach to perform the hierarchical sequential grooming to improve the joint performances based on a newly developed integrated auxiliary grooming graph (IAGG) that includes multiple wavelength integrated grooming graphs (WIGGs) and one waveband virtual topology layered graph (BVLG) to support both the multicast traffic grooming and multicast waveband grooming. In order to achieve the map of light-tree to the virtual topology layer in WIGG or BVLG, we present a light-segment map method, where a light-tree will be divided to several light-segments each of which will be independently mapped to the virtual topology layer. Since different definitions of blocking probability may lead to different objectives, we define two kinds of blocking probability, mean blocking probability of requests (MBPR) and mean blocking probability of users (MBPU). According to the two definitions of blocking probability, we propose two multicast multi-granular grooming heuristic algorithms, Heuristic Algorithm with minimizing MBPR and Heuristic Algorithm with minimizing MBPU based on IAGG. Simulation results show that the two proposed algorithms are both efficient and have better performances than traditional multicast grooming algorithm.

Multicast Grooming Algorithms in Waveband Switching Multi-Domain Optical Networks

In this paper, we study the multicast waveband grooming in multi-domain optical networks and propose three heuristic algorithms, Per-Domain Multicast Grooming (PDMG), Virtual Topology Multicast Grooming (VTMG) and Hierarchical Multi-domain Multicast Grooming (HMMG). Simulation results show that, comparing with PDMG and VTMG, HMMG has the best performance of ports savings and the lowest blocking probability.

Multi-cast waveband grooming algorithms in multi-domain optical networks

With the increasing of number of multimedia network applications, multi-cast services are becoming more and more popular. At the same time, the waveband switching technique is proposed to save ports and to reduce the cost of optical cross-connect. However, the existing multi-cast waveband grooming algorithms are mostly limited to single-domain optical networks. The size of optical backbones keeps enlarging, and the backbones are actually divided into multiple independent domains to provide the needed scalability and confidentiality. To solve these problems, the authors propose three heuristic algorithms: per-domain multi-cast grooming (PDMG), virtual topology multi-cast grooming (VTMG) and hierarchical multi-domain multi-cast grooming (HMMG). The main difference between these algorithms is that the inter-domain routing is performed in a different manner; in other words, the routings in PDMG, VTMG and HMMG are computed based on the domain-by-domain fixed routing table, the high layer in the aggregative virtual topology of multi-domains and the hierarchical integrated multi-cast auxiliary graph, respectively. For the intra-domain routing, the three algorithms employ the same method based on an intra-domain multi-cast integrated auxiliary graph. Simulation results show that compared with PDMG and VTMG, HMMG has the best performance in terms of the number of ports saved and the blocking probability.

Green multicast grooming based on optical bypass technology

With the network traffic increasing, the energy consumption of network equipments is growing greatly. Under the background of serious greenhouse effect, the excessive energy consumption has become a major barrier of developing the future information society. For this reason, the issue of saving energy followed by the grooming and optical bypass technology has become particularly important. In this paper, in order to perform the energy-saving for multicast demands, we present the multicast grooming policies and also develop a new auxiliary graph to support the multicast routing in green optical network. Based on the proposed auxiliary graph, a novel Multicast Green Grooming (MGG) approach by using the energy-efficient optical bypass technology and the effective grooming policy combination is proposed to reduce the occupied energy-consuming equipments that mainly include the core router ports, optical transceivers and amplifiers. Simulation results show that, compared to the traditional approach, MGG not only can obtain the lower blocking probability but also is able to save significant energy.

Multicast Grooming Algorithm in Waveband Switching Optical Networks

In optical Wavelength-Division-Multiplexing (WDM) networks, multicast becomes more and more popular to provide high-speed communication between one point and multiple points. At the same time, the ports of Optical Cross-Connect (OXC) are greatly enhanced with the increasing number of wavelengths in fibers, and then the waveband switching technique is proposed to save the ports and reduce the cost of OXC. However, current waveband grooming algorithms are all limited in unicast. To achieve the multicast communication and meanwhile save the ports of OXC, we need to solve the multicast grooming, routing and wavelength/waveband assignment problem which is the HP-hard. In this paper, we propose a heuristic algorithm named Integrated Multicast Waveband Grooming (IMWG) based on Multicast Layered Auxiliary Graph (MLAG) that includes a Virtual Topology Layer (VTL) and multiple Waveband-Plane Layers (WPLs) to support the single-hop, multi-hop and hybrid multicast waveband grooming. For each demand, IMWG first computes a single-hop or multi-hop grooming waveband-tree on VTL. If the grooming waveband-tree cannot be found on VTL, IMWG computes a new waveband-tree on WPL. If the new waveband-tree cannot be found on WPL, IMWG computes a hybrid grooming waveband-tree on MLAG. Simulation results show that, compared with other algorithms, IMWG is able to obtain better performances.

Dynamic provisioning of low-speed unicast/multicast traffic demands in mesh-based WDM optical networks

This paper addresses the problem of dynamically provisioning both low-speed unicast and multicast connection requests in mesh-based wavelength division multiplexing (WDM) optical networks. Several routing/provisioning schemes to dynamically provision both unicast and multicast connection requests are presented. In addition, a constraint-based grooming strategy is devised to utilize the overall network resources as efficiently as possible. Based on this strategy, several different sequential multicast grooming heuristics are first presented. Then, we devise a hybrid grooming approach and combine it with sequential approaches to achieve a grooming scheme that is biased toward serving multicast traffic demands in comparison with all other sequential grooming approaches. To achieve our objective, we decompose the problem into four subproblems: 1) routing problem; 2) light-tree-based logical-topology-design problem; 3) provisioning problem; and 4) traffic-grooming problem. The simulation results of the proposed schemes are compared with each other and with those of conventional nongrooming approaches. To the best of our knowledge, this is the first detailed paper to address and examine the problem of grooming dynamic multicast traffic demands.