Tania Panayiotou

Multicast Routing Algorithms Based on

We use novel ldquolight-tree balancing techniquesrdquo to investigate the problem of provisioning multicast sessions in metropolitan all-optical networks. The Q-factor for every path of a derived light-tree is calculated taking into account several physical layer constraints in the network and using a Q-budgeting approach. Based on the above performance, tree balancing techniques are applied to maximize the number of multicast connections that can be admitted to the network.

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This paper investigates the problem of protecting multicast sessions in optical networks utilizing a novel segment-based protection heuristic algorithm called LP (level protection). The proposed scheme exhibits improved performance in terms of blocking probability compared to other traditional segment-based multicast protection schemes, especially when sharing techniques are also utilized. Furthermore, when physical layer impairments are also taken into account for the calculation of the working and protection light-trees, it is shown that the LP technique presents significant improvement in performance compared to the other commonly used protection techniques.

-Factor Physical-Layer Constraints in Metro Networks

In optical networks the effect of physical layer impairments can play an important role in the routing and wavelength assignment decisions that are taken in the control layer. Furthermore, as networks evolve to support more bandwidth-intensive applications, and as rich multimedia and real-time services become more popular, next-generation networks are expected to support traffic that will be heterogeneous in nature with both unicast and multicast applications. In this chapter we investigate the problems of routing and wavelength assignment in transparent optical networks that support unicast and multicast applications, while taking into consideration the physical layer impairments during the provisioning of each application.

Segment-based protection of multicast connections in metropolitan area optical networks with quality-of-transmission considerations

This work investigates the static impairment-aware multicast routing and wavelength assignment (IA-MC-RWA) problem for transparent Wavelength Division Multiplexing (WDM) metro networks. The IA-MC-RWA problem, known to be NP-complete, is first formulated mathematically as an integer linear program (ILP) taking into account a number of impairments encountered by the multicast connections at the physical layer. Efficient heuristics are also developed to solve the multicast routing problem with practical network size parameters. To evaluate the heuristics, their optimality is first examined by comparing their performance results to the results of the ILP for a small-sized network. Their performance is subsequently evaluated over a practical-sized problem. The proposed Q-based Steiner Tree (QBST) heuristic that takes the physical layer impairments (PLIs) into consideration during the provisioning phase of the multicast tree, outperforms the rest of the multicast routing heuristic algorithms developed for comparison purposes and provides results closer to the optimal compared to the ILP.

Impairment-Aware Optical Networking: A Survey

This paper investigates the problem of protecting multicast sessions in optical networks utilizing a novel cycle-based heuristic algorithm called Q-based p-Cycles Heuristic (QBPCH), that is used for the decomposition of the graph network into a set of p-cycles, while taking into account the physical layer impairments (PLIs) via a Q-budgeting approach. In this technique the length of these cycles is constrained in order to limit the effect of the impairments on the protection paths. The proposed scheme exhibits improved performance in terms of blocking probability, when compared to another proposed heuristic, namely p-Cycles Heuristic (PCH), that aims at decomposing the graph network into a set of p-cycles that maximizes the number of straddling links in the network. Both proposed schemes are also compared to a traditional ring cover heuristic (RC) and to a Hamiltonian cycle (HC) approach and it is shown that QBPCH performs the best in terms of blocking probability when the PLIs are considered.

Impairment-aware multicast session provisioning in metro optical networks

This paper investigates the problem of designing, engineering and evaluating metropolitan area transparent optical networks for the provisioning of multicast sessions. Apart from finding the minimum cost tree, our proposed technique utilizes a metric on the physical performance of the system, namely the Q-factor of the system, by calculating Q-penalties for impairments via a Q-budgeting approach, to investigate whether a multicast connection should be admitted to the network. It uses ldquotree balancing techniquesrdquo for the multicast sessions aiming at maximizing the multicast connections that can be admitted to the network.

p-Cycle-based protection of multicast connections in metropolitan area optical networks with physical layer impairments constraints

This paper investigates the problem of protecting multicast sessions in transparent optical networks. It utilizes a novel cycle based heuristic algorithm called Q-based p-Cycles Heuristic (QBPCH), that is used for the decomposition of the graph network into a set of p-cycles, while taking into account the physical layer impairments (PLIs) via a Q-budgeting approach. In this technique the length of these cycles is constrained in order to limit the effect of the impairments for the protection paths. The proposed scheme exhibits improved performance in terms of blocking probability when compared to a traditional ring cover heuristic (RC) and to a Hamiltonian cycle (HC) approach.

Multicasting with physical-layer constraints in metropolitan area networks

This paper investigates the problem of multicast traffic grooming in transparent optical networks utilizing a grooming approach that is based on 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 are consisting of both the available physical links and the logical links with available free capacity. Two schemes for building the HGs are proposed, namely the minimum free capacity light-tree first (MCF) and the maximum free capacity light-tree first (MXCF), and also a novel hybrid Steiner tree (HST) heuristic for routing/grooming on HGs is presented. The proposed routing/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.

p-Cycle-based protection of multicast connections in metropolitan area optical networks with quality-of-transmission considerations

This work examines protection of multicast sessions in optical networks utilizing a novel segment-based algorithm called Level Protection. Our proposed scheme exhibits improved performance compared to other segment-based multicast protection schemes.

Hybrid graph-based traffic grooming for multicast connections in mesh optical networks

Different node design architectures and node engineering approaches are considered for fully-transparent metropolitan area optical networks for the provisioning of multicast sessions. A number of multicast routing approaches are considered that take into account the physical layer constraints. The goal of this work is to minimize the overall blocking probability in the network, while ensuring that the provisioned multicast connections meet a prescribed bit error rate.