Ashok Kumar Pradhan

A Cost Efficient Multicast Routing and Wavelength Assignment in WDM Mesh Network

Multicast Routing and Wavelength Assignment (MRWA) is a technique implemented in WDM optical networks, where dedicated paths are established between a source and a set of destinations, unlike unicasting where a source is connected with only one destination. For a multicast session request a multicast tree is generated to establish a connection from source to all the destinations. A wavelength is assigned to each and every branches of the generated multicast tree to create a light-tree for the session. In this work, we have tried to minimize the wavelength usage to establish multicast sessions for a set of multicast session requests. Our approach is to minimize the size of the multicast tree by sharing branches, as much as possible, to connect all the destinations from the source node. A lesser usage of links minimizes the collision probability for the assignment of wavelength, say w, in each of the selected links to be assigned the wavelength. Secondly, greater sharing implies lesser splitting. As splitters are costly, minimum usage of splitters incurs lesser infrastructure cost in the network. The effectiveness of our approach has been established through extensive simulation on different set of multicast session under different network topologies and comparing with standard Minimal Spanning Tree (MST) based algorithm. The simulation shows our algorithm performs better than the MST based algorithm.

Survivable of multicast traffic grooming against single link failures in WDM mesh networks

In Wavelength Division Multiplexing (WDM) optical networks, the failure of network resources (e.g., fiber link or node) can disrupt the transmission of information to several destination nodes on a light-tree based multicast sessions. Thus, it is essential to protect multicast sessions by reserving resources along back-up trees. So that if primary tree fails to transmit the information back-up tree will forward the message to the desired destinations. In this paper, we address the problem of survivable of multicast routing and wavelength assignment with sub-wavelength traffic demands in a WDM mesh networks. In this work, we extend the approach of segment disjoint protection methodology to groom the multicast sessions in order to protect them from single link failures. We have proposed an efficient approach for protecting multicast sessions named light-tree based shared segment protection grooming (LTSSPG) scheme and compared with existing multicast traffic grooming with segment protection (MTG-SP) approach. In case of MTG-SP, each segment of primary tree is protected by dis-joint segment in the back-up tree to share the edges or segment. Whereas in case of LTSSPG approach, the segment are shared between the primary as well as back-up trees. The main objective of this work is to minimize the cost in terms of number of wavelengths requirement and optical splitters as well as minimizing the blocking probability of network resources. The performance of various algorithms are evaluated based on extensive simulations in standard networks.

Knapsack based multicast traffic grooming for optical networks

Abstract This paper proposes a light-tree based heuristic algorithm, called 0/1 knapsack based multicast traffic grooming, in order to minimize the network cost by reducing the number of higher layer electronic and optical devices, such as transmitters, receivers, and splitters, and used wavelengths in the network. The proposed algorithm constructs light-trees or sub light-trees, which satisfy sub bandwidth demands of all multicast requests. We present a light-tree based integer linear programming (ILP) formulation to minimize the network cost. We solve the ILP problem for sample four-node and six-node networks and compare the ILP results with the proposed heuristic algorithm. We observe that the performance of the proposed algorithm is comparable to the ILP in terms of cost. When the introduced ILP is not tractable for large network, the proposed algorithm still able to find the results. Furthermore, we compare the proposed heuristic algorithm to existing heuristic algorithms for different backbone networks. Numerical results indicate that the proposed heuristic algorithm outperforms the conventional algorithms in terms of cost and resource utilization.

Multicast dynamic traffic grooming using bin packing method in WDM mesh networks

Abstract With the development of multimedia services in Internet technology, there comes a big gap between bandwidth utilization and the blocking probability for multicast requests in the optical wavelength division multiplexing (WDM) networks. The objective of the proposed approach is to minimize the number of requests blocked in a dynamic multicast optical networks by minimizing the total resources (such as transceivers, splitters and wavelengths) used by the requests and simultaneously increase the bandwidth utilization. Since there are multiple wavelengths on a WDM optical fiber of fixed capacities, minimizing the number of wavelengths to be used is a variation of the bin packing problem. In the bin packing problem, multicast requests of different granularities or subwavelengths must be packed into a finite number of wavelength channels, in such a fashion that it minimizes the number of wavelengths used. In computational complexity theory, it is a combinatorial NP-hard problem. Therefore, we propose two heuristic approaches that provide the efficient resource utilization. These algorithms are called Multicast Traffic Grooming with Bin packing Best-Fit (MTG-BBF) and Multicast Traffic Grooming with Bin packing First-Fit (MTG-BFF). Both the algorithms are derived from standard Bin pack heuristic approach and we map our problem with such kind of approach. Our simulations demonstrated that both the algorithms significantly reduce the blocking probability (BP) compared to well known existing algorithms and MTG-BFF produces slightly better performance than MTG-BBF in the standard networks.

Multicast protection and grooming scheme in survivable WDM optical networks

Network survivability is an important factor in the design of WDM optical networks. In dynamic provisioning context, a typical connection request may require bandwidth less than a wavelength channel capacity and it may also require protection from network failure, typically fiber cuts. In this paper, we investigate the multicast traffic protection with grooming in WDM mesh network under single link failure and propose a novel multicast protection algorithm called shared segment protection with grooming (SSPG) that constructs the primary or working light-tree and corresponding link disjoint backup light-tree for each dynamic multicast connection request. In this approach, a backup segment can efficiently share the wavelength channel capacity of its working segments and simultaneously use the common network resources at the backup light-tree. In order to efficiently utilize the network resources (such as wavelength, transceivers, optical splitters and wavelength channels), the sub-wavelength demands are groomed to protect multicast requests against single link failure. The main objective of this work is to minimize the blocking probability of client calls or bandwidth blocking probability of a dynamically changing multicast request of WDM optical networks and efficiently utilize the network resources, respectively. The performances of various algorithms are evaluated based on extensive simulations to study dynamic provisioning of survivable multicast sessions in standard WDM mesh networks. The simulation results reveal that the proposed SSPG produces better performance in terms of blocking probability (in terms of requests), bandwidth blocking probability (in terms of bandwidth capacity), wavelength channel utilization and cost which is associated with the network resources such as transceivers, splitters and wavelengths than existing standard link shared protection with grooming (LSPG) and path-pair shared protection with grooming (PSPG) algorithms.

Multicast traffic grooming with survivability in WDM mesh networks

Survivability of traffic grooming problem for optical mesh networks is employed in WDM mesh networks. A typical connection request may require bandwidth capacity which is lesser than the wavelength channel capacity of an optical fiber network, and it may also require protection from link failures of the network, typically fiber cut. As higher layer electronic ports, such as transceivers and optical splitters are dominant cost factors of an optical network, it is essential to reduce their number of use when grooming the multicast traffic into high bandwidth light-trees. This paper, provides an near optimal cost design of WDM networks with survivable multicast traffic grooming under static traffic demands. In this paper, we have proposed a heuristic approach called Multicast Traffic Grooming with Survivability (MTGS) at light-tree level for grooming a connection request with segment protection. In this segment protection scheme, backup paths use the network resources (such as transceivers, optical splitters and wavelengths), as long as their working paths are failed simultaneously. In our proposed approach, working paths and backup paths are groomed separately and protecting each specific link when two links failed simultaneously. The main objective of this approach is to minimize the cost of the network which is associated with network resources. We have compared our work with existing approach called logical-first sequential routing with single-hop grooming (LFSEQSH) and logical-first sequential routing with multi-hop grooming (LFSEQMH) algorithms. In the existing multicast traffic algorithms, we add survivability with traffic grooming in static traffic environment. The results, thus obtained by comparison depict that our proposed approach yields better performance in term of network cost than existing algorithms.

Multicast Traffic Grooming in Sparse Splitting WDM Mesh Networks

With the growing popularity of multicast applications and the recognition of the potential achievable efficiency gain of the traffic grooming, we face the challenge of optimizing the design of WDM optical networks with sparse splitting multicast traffic grooming. Efficiently grooming low speed connections onto a high capacity wavelength channel can significantly improve the bandwidth utilization in an optical network. In this study, we investigate the problem of sub-wavelength traffic grooming in a WDM optical networks and shows how to take the advantages of multicast capable nodes in grooming these sub-wavelength traffic. The problem of constructing optimal multicast routing trees and grooming their traffics in WDM optical mesh networks is NP-hard. Therefore, we propose an heuristic approach to solve the problem in an efficient manner. The main objective of this paper is to maximize the bandwidth utilization and simultaneously minimize the wavelength usage in a sparse splitting optical network. The problem is mathematically formulated. We have simulated the proposed heuristic approach Multicast Sparse Splitting Traffic Grooming (MSSTG) with different network topologies and compared the performance with Multicast Traffic Grooming with Shortest Path (MTG-SP) algorithm. The simulation results shows that the proposed approach produces better result than existing MTG-SP algorithm.

Resource efficient multicast traffic grooming in WDM mesh networks

In this paper, we have considered an optimal design and provisioning of WDM networks for the grooming of sub-wavelengths traffic requests. As higher layer electronic ports, such as transceivers and optical splitters are dominant cost factors of an optical network, it is essential to reduce their numbers of use while grooming the multicast traffic requests into high bandwidth light-trees. This paper provides an optimal cost design of WDM networks with multicast traffic grooming under static traffic demand. We develop a unified framework for the optimal provisioning of different practical scenarios of multicast traffic grooming in a static traffic scenario. In this study, we design an Integer linear Programming (ILP) formulation for multicast traffic grooming to minimize the cost associated with the higher layer electronic ports such as transceivers, splitters and wavelengths, and simultaneously maximize the bandwidth utilization of the network. We propose a heuristic algorithm called Efficient Light-Tree based Multicast Traffic Grooming (ELT-MTG) algorithm to achieve scalability in large size optical networks. Simulations are conducted on several standard well-known WDM mesh networks to study the design cost (based on number of transceivers, optical splitters and wavelengths) used in the networks. The result, thus obtained by comparison, helped us to conclude that the proposed approach ELT-MTG gives better performance than well-known existing logical-first sequential routing with single-hop grooming (LFSEQSH) and logical-first sequential routing with multi-hop grooming (LFSEQMH) algorithms in a static traffic environment.