The Experts below are selected from a list of 6465 Experts worldwide ranked by ideXlab platform
Sanjay Jha - One of the best experts on this subject based on the ideXlab platform.
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failure oriented Path Restoration algorithm for survivable networks
Network Operations and Management Symposium, 2004Co-Authors: William Lau, Sanjay JhaAbstract:A new polynomial-time approximation algorithm called service Path local optimization (SPLO) is presented. SPLO is shown to perform competitively with existing non-polynomial approximations based on the failure-oriented approach. SPLO is designed for online computation where only one request is computed at a time, and the decision making does not depend on future requests. The polynomial-time and online nature of the algorithm makes SPLO suitable for use in real-time on-demand Path request applications. In addition, a non-polynomial approximation algorithm based on SPLO called nSPLO is proposed. Result shows that spare capacity is reduced significantly but at the cost of substantially higher computation run-time. The paper also introduces a new concept called Path intermix where the service Path's allocated bandwidth can be used by the backup Paths protecting that particular service Path. The result shows that Path intermix can reduce spare capacity by up to 5% for single node failure.
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failure oriented Path Restoration algorithm for survivable networks
IEEE Transactions on Network and Service Management, 2004Co-Authors: William Lau, Sanjay JhaAbstract:In this article, a new polynomial-time approximation algorithm called Service Path Local Optimization (SPLO) is proposed for the online Restoration problem. SPLO is shown to perform competitively with existing offline heuristics algorithm in terms of spare capacity. SPLO is designed for online computation where only one request is computed at any one time, and the decision making does not depend on future requests. The polynomial-time and online nature of the algorithm makes SPLO suitable for use in real-time on-demand Path request applications. SPLO can be combined with a non-polynomial post-processing component that re-optimizes the backup Paths. Significant reductions in spare capacity requirements are achievable at the expense of higher computation time. Further, the potential for SPLO as an algorithm in traffic engineering applications is investigated by looking at the performance impact when source-destination-based traffic aggregation is applied. We also introduce a new concept called Path intermix where the service Path?s allocated bandwidth can be used by the backup Paths protecting that particular service Path.
W D Grover - One of the best experts on this subject based on the ideXlab platform.
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Design of a meta-mesh of chain subnetworks: enhancing the attractiveness of mesh-restorable WDM networking on low connectivity graphs
IEEE Journal on Selected Areas in Communications, 2002Co-Authors: W D Grover, J. DoucetteAbstract:We have developed a design refinement to increase the capacity efficiency of span-restorable mesh networks on sparse facility graphs. The new approach views the network as a "meta-mesh of chain subnetworks". This makes the prospect of WDM mesh networking more economically viable than with previous mesh-based designs where the average nodal degree is low. The meta-mesh graph is a homeomorphism of the complete network in which edges are either direct spans or chains of degree-2 nodes. The main advantage is that loop-back-type spare capacity is provided only for the working demands that originate or terminate in a chain and not for the entire flow that crosses a chain. The transiting ("express") flows are entirely mesh-protected within the meta-mesh graph which is of higher average degree and hence efficiency for mesh Restoration than the network as a whole. Nodal equipment savings also arise from the grooming of express lightPaths onto the logical chain-bypass span. Only the meta-mesh nodes need optical cross-connect functionality. Other sites use OADMs and/or glassthroughs. The resultant designs comprise a special class of restorable network that is intermediate between pure span Restoration and Path Restoration. Most of the efficiency of Path Restoration is achieved, but with a span Restoration mechanism which is more localized and potentially faster and simpler than Path Restoration. The concept lends itself to implementation with OADMs having a passive waveband pass-through feature to support the logical chain bypass spans for express lightPaths.
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a highly efficient Path Restoration protocol for management of optical network transport integrity
IEEE Journal on Selected Areas in Communications, 2000Co-Authors: Rainer R Iraschko, W D GroverAbstract:Distributed Path Restoration based on optical cross-connects can provide highly capacity-efficient real-time Restoration for WDM-based optical networking. However, to obtain an assured Restoration level with the theoretically very low amounts of spare capacity that Path Restoration allows, one must solve, or closely approximate a solution to, the integer multicommodity maximum flow (MCMF) problem, MCMF is, however a hard combinatorial optimization problem due to what is called the "mutual capacity" aspects of the problem: which of many competing origin-destination pairs should be allowed Paths over the finite spares on each span? Integer MCMF is further complicated by the nonunimodular nature of the problem, i.e., fractional flows are forbidden but would arise if solved by linear programming. This paper presents a heuristic principle that tests well against integer programming solutions of MCMF routing. The heuristic is first characterized in a centralized program, then adapted for use in a distributed Path Restoration protocol. In all test cases, the protocol obtains over 97% of the Paths found in an optimal MCMF solution in the same network. Via OPNET simulation it is also predicted that the protocol will run in well under 2 seconds which means it could be used directly in real-time, or in distributed prefailure self-planning, for Restoration. The significance is that network operators could aggressively optimize their spare capacity, toward theoretical minimums, while still assuring 100% restorability.
J Comellas - One of the best experts on this subject based on the ideXlab platform.
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experimental assessment of bulk Path Restoration in multi layer networks using pce based global concurrent optimization
Journal of Lightwave Technology, 2014Co-Authors: Alberto Castro, Ricardo Martinez, Ramon Casellas, Luis Velasco, Raul Munoz, R Vilalta, J ComellasAbstract:Generalized multi-protocol label switching-based multi-layer networks (MLN) combining packet and optical switching lead to jointly leverage intrinsic per-layer benefits such as statistical multiplexing and huge transport capacity. By doing so, efficient network resource utilization is attained through MLN traffic engineering (TE) strategies, i.e. grooming. In this context, an optical link failure may cause the disruption of multiple groomed packet label switched Paths (LSPs). Thereby, efficient recovery schemes such as Restoration are required. In dynamic Restoration, the centralized Path computation element (PCE) sequentially computes backup Paths for the set of failed packet LSPs using the TE database (TED). Since the TED is not updated until an LSP is actually set up, it is very likely that the PCE assigns the same network resources to different backup Paths. This does increase resource contention and not fully exploits the potential grooming opportunities among the backup LSPs; consequently, the restorability metric performs poorly. To improve this, a designed PCE global concurrent optimization (GCO) architecture is implemented favoring grooming and lowering resource contention. The addressed problem, referred to as bulk Path Restoration in multi-layer optical networks (BAREMO), is formally modeled and stated using a mixed integer linear programming formulation. Then, a heuristic algorithm solving the BAREMO problem is devised. The experimental performance evaluation is conducted within the ADRENALINE testbed. Besides validating the PCE GCO architecture, its performance is compared with a sequential PCE for several traffic loads and failure rates. The results show that the PCE GCO improves remarkably restorability compared to the sequential PCE at the expenses, however, of increasing the Restoration time.
William Lau - One of the best experts on this subject based on the ideXlab platform.
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failure oriented Path Restoration algorithm for survivable networks
Network Operations and Management Symposium, 2004Co-Authors: William Lau, Sanjay JhaAbstract:A new polynomial-time approximation algorithm called service Path local optimization (SPLO) is presented. SPLO is shown to perform competitively with existing non-polynomial approximations based on the failure-oriented approach. SPLO is designed for online computation where only one request is computed at a time, and the decision making does not depend on future requests. The polynomial-time and online nature of the algorithm makes SPLO suitable for use in real-time on-demand Path request applications. In addition, a non-polynomial approximation algorithm based on SPLO called nSPLO is proposed. Result shows that spare capacity is reduced significantly but at the cost of substantially higher computation run-time. The paper also introduces a new concept called Path intermix where the service Path's allocated bandwidth can be used by the backup Paths protecting that particular service Path. The result shows that Path intermix can reduce spare capacity by up to 5% for single node failure.
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failure oriented Path Restoration algorithm for survivable networks
IEEE Transactions on Network and Service Management, 2004Co-Authors: William Lau, Sanjay JhaAbstract:In this article, a new polynomial-time approximation algorithm called Service Path Local Optimization (SPLO) is proposed for the online Restoration problem. SPLO is shown to perform competitively with existing offline heuristics algorithm in terms of spare capacity. SPLO is designed for online computation where only one request is computed at any one time, and the decision making does not depend on future requests. The polynomial-time and online nature of the algorithm makes SPLO suitable for use in real-time on-demand Path request applications. SPLO can be combined with a non-polynomial post-processing component that re-optimizes the backup Paths. Significant reductions in spare capacity requirements are achievable at the expense of higher computation time. Further, the potential for SPLO as an algorithm in traffic engineering applications is investigated by looking at the performance impact when source-destination-based traffic aggregation is applied. We also introduce a new concept called Path intermix where the service Path?s allocated bandwidth can be used by the backup Paths protecting that particular service Path.
Alberto Castro - One of the best experts on this subject based on the ideXlab platform.
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experimental assessment of bulk Path Restoration in multi layer networks using pce based global concurrent optimization
Journal of Lightwave Technology, 2014Co-Authors: Alberto Castro, Ricardo Martinez, Ramon Casellas, Luis Velasco, Raul Munoz, R Vilalta, J ComellasAbstract:Generalized multi-protocol label switching-based multi-layer networks (MLN) combining packet and optical switching lead to jointly leverage intrinsic per-layer benefits such as statistical multiplexing and huge transport capacity. By doing so, efficient network resource utilization is attained through MLN traffic engineering (TE) strategies, i.e. grooming. In this context, an optical link failure may cause the disruption of multiple groomed packet label switched Paths (LSPs). Thereby, efficient recovery schemes such as Restoration are required. In dynamic Restoration, the centralized Path computation element (PCE) sequentially computes backup Paths for the set of failed packet LSPs using the TE database (TED). Since the TED is not updated until an LSP is actually set up, it is very likely that the PCE assigns the same network resources to different backup Paths. This does increase resource contention and not fully exploits the potential grooming opportunities among the backup LSPs; consequently, the restorability metric performs poorly. To improve this, a designed PCE global concurrent optimization (GCO) architecture is implemented favoring grooming and lowering resource contention. The addressed problem, referred to as bulk Path Restoration in multi-layer optical networks (BAREMO), is formally modeled and stated using a mixed integer linear programming formulation. Then, a heuristic algorithm solving the BAREMO problem is devised. The experimental performance evaluation is conducted within the ADRENALINE testbed. Besides validating the PCE GCO architecture, its performance is compared with a sequential PCE for several traffic loads and failure rates. The results show that the PCE GCO improves remarkably restorability compared to the sequential PCE at the expenses, however, of increasing the Restoration time.