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Biswanath Mukherjee - One of the best experts on this subject based on the ideXlab platform.
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optical wdm networks
2006Co-Authors: Biswanath MukherjeeAbstract:Optical Networking: Principles and Challenges.- Enabling Technologies: Building Blocks.- Local, Access, and Metro Networks.- Single-Hop Networks.- Multihop Networks.- Optical Access Networks.- Optical Metro Networks.- Wavelength-Routed (Wide-Area) Optical Networks.- Routing and Wavelength Assignment.- Elements of Virtual-Topology Design.- Advanced Topics in Virtual-Topology Optimization.- Wavelength Conversion.- Survivable WDM Networks.- Light-Tree: Optical Multicasting.- Traffic Grooming.- Advanced Topics in Traffic Grooming.- All-Optical Impairment-Aware Routing.- Network Control and Management.- Optical Packet Switching (OPS).- Optical Burst Switching (OBS).
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minimum cost Virtual Topology adaptation for optical wdm mesh networks
International Conference on Communications, 2005Co-Authors: S F Gieselman, N K Singhal, Biswanath MukherjeeAbstract:This study considers reducing cost to ISPs by allowing them to dynamically lease only the required amount of bandwidth from network operators in order to satisfy their customers' traffic needs. Network operators can also generate additional revenue from this approach by leasing out the spare bandwidth to time-of-the-day-insensitive applications. We study a Virtual-Topology adaptation model for the ISP based on minimizing its total dollar cost for running its network. Relative to the flat-rate model (where the ISP's Topology is fixed based on worst-case traffic), our minimum-cost Virtual-Topology adaptation method can yield significant cost savings of over 21% (based on a US ISP network employing realistic traffic and bandwidth costs). Our optimization approach is based on a mixed integer linear program (MILP) which nominally adds or deletes one link (lightpath) in the ISP's Virtual Topology at a time after a certain observation period, which is a few hundreds of seconds.
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Virtual Topology adaptation for wdm mesh networks under dynamic traffic
IEEE ACM Transactions on Networking, 2003Co-Authors: A Gencata, Biswanath MukherjeeAbstract:We present a new approach to the Virtual-Topology reconfiguration problem for a wavelength-division-multiplexing-based optical wide-area mesh network under dynamic traffic demand. By utilizing the measured Internet backbone traffic characteristics, we propose an adaptation mechanism to follow the changes in traffic without a priori knowledge of the future traffic pattern. Our work differs from most previous studies on this subject which redesign the Virtual Topology according to an expected (or known) traffic pattern, and then modify the connectivity to reach the target Topology. The key idea of our approach is to adapt the underlying optical connectivity by measuring the actual traffic load on lightpaths continuously (periodically based on a measurement period) and reacting promptly to the load imbalances caused by fluctuations on the traffic, by either adding or deleting one or more lightpath at a time. When a load imbalance is encountered, it is corrected either by tearing down a lightpath that is lightly loaded or by setting up a new lightpath when congestion occurs. We introduce high and low watermark parameters on lightpath loads to detect any over- or underutilized lightpath, and to trigger an adaptation step. We formulate an optimization problem which determines whether or not to add or delete lightpaths at the end of a measurement period, one lightpath at a time, as well as which lightpath to add or delete. This optimization problem turns out to be a mixed-integer linear program. Simulation experiments employing the adaptation algorithm on realistic network scenarios reveal interesting effects of the various system parameters (high and low watermarks, length of the measurement period, etc.). Specifically, we find that this method adapts very well to the changes in the offered traffic.
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Virtual Topology adaptation for wdm mesh networks under dynamic traffic
International Conference on Computer Communications, 2002Co-Authors: A Gencata, Biswanath MukherjeeAbstract:We present a new approach to the Virtual-Topology reconfiguration problem for wavelength-routed, optical wide-area networks under dynamic traffic demand. By utilizing the measured Internet backbone traffic characteristics, an adaptation mechanism is proposed to follow the changes in traffic without assuming that the future traffic pattern is known. In that sense, our work differs from previous studies which redesign the Virtual-Topology according to an expected (or known) traffic pattern, and then modify the connectivity to reach the target Topology. The key idea of our approach is to adapt the underlying optical connectivity by measuring the actual traffic load on lightpaths continuously (periodically based on a measurement period) and reacting promptly to the imbalances caused by fluctuations in the traffic by adding or deleting one lightpath at a time. We aim to correct the encountered load imbalance directly, either by tearing down a lightpath that is lightly loaded or by setting up a new lightpath when congestion occurs. We introduce high and low watermark parameters on lightpath loads to detect any over/underutilized lightpath, and to trigger an adaptation step. The adaptation method is evaluated through simulations and the effect of system parameters (high and low watermarks, length of the measurement period) are investigated.
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fault management in ip over wdm networks wdm protection versus ip restoration
IEEE Journal on Selected Areas in Communications, 2002Co-Authors: L Sahasrabuddhe, S Ramamurthy, Biswanath MukherjeeAbstract:We consider an IP-over-WDM network in which network nodes employ optical crossconnects and IP routers. Nodes are connected by fibers to form a mesh Topology. Any two IP routers in this network can be connected together by an all-optical wavelength-division multiplexing (WDM) channel, called a lightpath, and the collection of lightpaths that are set up form a Virtual Topology. In this paper, we concentrate on single fiber failures, since they are the predominant form of failures in optical networks. Since each lightpath is expected to operate at a rate of few gigabits per second, a fiber failure can cause a significant loss of bandwidth and revenue. Thus, the network designer must provide a fault-management technique that combats fiber failures. We consider two fault-management techniques in an IP-over-WDM network: (1) provide protection at the WDM layer (i.e., set up a backup lightpath for every primary lightpath) or (2) provide restoration at the IP layer (i.e., overprovision the network so that after a fiber failure, the network should still be able to carry all the traffic it was carrying before the fiber failure). We formulate these fault-management problems mathematically, develop heuristics to find efficient solutions in typical networks, and analyze their characteristics (e.g., maximum guaranteed network capacity in the event of a fiber failure and the recovery time) relative to each other.
Byrav Ramamurthy - One of the best experts on this subject based on the ideXlab platform.
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a scalable approach for survivable Virtual Topology routing in optical wdm networks
IEEE Journal on Selected Areas in Communications, 2007Co-Authors: Ajay Todimala, Byrav RamamurthyAbstract:The survivable Virtual Topology routing problem is to route a Virtual Topology graph on a optical fiber physical Topology such that the Virtual Topology remains connected when failures occur in the physical Topology. In this work we study the problem of survivable Virtual Topology routing under single node/SRLG (Shared Risk Link Group) failure model. We prove that the survivable Virtual Topology routing problem under node/SRLG failures is NP-complete. We present an improved integer linear programming (ILP) formulation for computing the survivable routing of a Virtual Topology graph. However, ILP is not scalable when the network size scales more than a few tens of nodes. In this work, we present sub-classes of graphs which more accurately model an actual network and for which a survivable routing can be easily computed solving an ILP. We successfully computed the survivable routing of Virtual topologies belonging to these sub-classes against link/SRLG failures for topologies of size up to 24 nodes.
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survivable Virtual Topology routing under shared risk link groups in wdm networks
Broadband Communications Networks and Systems, 2004Co-Authors: Ajay Todimala, Byrav RamamurthyAbstract:Network survivability is one of the most important issues in the design of optical WDM networks. In this work we study the problem of survivable routing of a Virtual Topology on a physical Topology with shared risk link groups (SRLG). The survivable Virtual Topology routing problem against single-link failures in the physical Topology is proved to be NP-complete in E. Modiano and A. Narula-Tam, May 2002. We prove that survivable Virtual Topology routing problem against SRLG/node failures is also NP-complete. We present an improved integer linear programming (ILP) formulation (in comparison to E. Modiano and A. Narula-Tam, May 2002) for computing the survivable routing under SRLG/node failures. Using an ILP solver, we computed the survivable Virtual Topology routing against link and SRLG failures for small and medium sized networks efficiently. As even our improved ILP formulation becomes intractable for large networks, we present a congestion-based heuristic and a tabu search heuristic (which uses the congestion-based heuristic solution as the initial solution) for computing survivable routing of a Virtual Topology. Our experimental results show that tabu search heuristic coupled with the congestion based heuristic (used as initial solution) provides fast and near-optimal solutions.
Ajay Todimala - One of the best experts on this subject based on the ideXlab platform.
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a scalable approach for survivable Virtual Topology routing in optical wdm networks
IEEE Journal on Selected Areas in Communications, 2007Co-Authors: Ajay Todimala, Byrav RamamurthyAbstract:The survivable Virtual Topology routing problem is to route a Virtual Topology graph on a optical fiber physical Topology such that the Virtual Topology remains connected when failures occur in the physical Topology. In this work we study the problem of survivable Virtual Topology routing under single node/SRLG (Shared Risk Link Group) failure model. We prove that the survivable Virtual Topology routing problem under node/SRLG failures is NP-complete. We present an improved integer linear programming (ILP) formulation for computing the survivable routing of a Virtual Topology graph. However, ILP is not scalable when the network size scales more than a few tens of nodes. In this work, we present sub-classes of graphs which more accurately model an actual network and for which a survivable routing can be easily computed solving an ILP. We successfully computed the survivable routing of Virtual topologies belonging to these sub-classes against link/SRLG failures for topologies of size up to 24 nodes.
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survivable Virtual Topology routing under shared risk link groups in wdm networks
Broadband Communications Networks and Systems, 2004Co-Authors: Ajay Todimala, Byrav RamamurthyAbstract:Network survivability is one of the most important issues in the design of optical WDM networks. In this work we study the problem of survivable routing of a Virtual Topology on a physical Topology with shared risk link groups (SRLG). The survivable Virtual Topology routing problem against single-link failures in the physical Topology is proved to be NP-complete in E. Modiano and A. Narula-Tam, May 2002. We prove that survivable Virtual Topology routing problem against SRLG/node failures is also NP-complete. We present an improved integer linear programming (ILP) formulation (in comparison to E. Modiano and A. Narula-Tam, May 2002) for computing the survivable routing under SRLG/node failures. Using an ILP solver, we computed the survivable Virtual Topology routing against link and SRLG failures for small and medium sized networks efficiently. As even our improved ILP formulation becomes intractable for large networks, we present a congestion-based heuristic and a tabu search heuristic (which uses the congestion-based heuristic solution as the initial solution) for computing survivable routing of a Virtual Topology. Our experimental results show that tabu search heuristic coupled with the congestion based heuristic (used as initial solution) provides fast and near-optimal solutions.
Lei Guo - One of the best experts on this subject based on the ideXlab platform.
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survivable routing algorithm with mixed shared protection in fault tolerant gmpls multi layered optical networks
European Transactions on Telecommunications, 2010Co-Authors: Lei Guo, Xingwei Wang, Jiannong Cao, Xuetao Wei, Qiming Gai, Zhaolong NingAbstract:In this paper, we studied survivability in general multi-protocol label switching (GMPLS) multi-layered optical networks and proposed a novel mixed shared protection algorithm (MSPA) based on the integrated layered graph (ILG) to tolerate single-fibre link failure. The ILG is composed of one Virtual Topology layer (VTL), corresponding to IP/MPLS layer; multiple wavelength-plane layers (WPLs), corresponding to the wavelength-division multiplexing (WDM) optical layer; and some Virtual links that connect the VTL to each WPL in order to solve the problem on routing, wavelength assignment and low-speed traffic grooming. For every connection request, the MSPA first computes a single-hop or multi-hop label switching path (LSP) pair, involving a working LSP and a physical link-disjoint backup LSP in the VTL. If the LSP pair is not found in the VTL, the MSPA computes the new LSP pair in the WPL. Conversely, if the new LSP pair is not detected in the WPL, the MSPA computes the hybrid multi-hop LSP pair in the ILG. In the MSPA, if the two working LSPs are in physical link-disjoint, their corresponding backup LSPs can share the backup bandwidth. In addition, the working LSPs and the backup LSPs can also share the same mixed of wavelength, in which the different bandwidths can be assigned to different working and backup LSPs. Simulation results show that, compared to previous algorithm, the MSPA can obtain a better bandwidth utilisation ratio (BUR) with a lower blocking probability. Copyright © 2010 John Wiley & Sons, Ltd.
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local and global hamiltonian cycle protection algorithm based on abstracted Virtual Topology in fault tolerant multi domain optical networks
IEEE Transactions on Communications, 2010Co-Authors: Lei Guo, Xingwei Wang, Jiannong Cao, Weigang HouAbstract:Since current optical network is actually divided into multiple domains each of which has its own network provider for independent management, the development of multi-domain networks has become the trend of next-generation intelligent optical networks, and then the survivability has also become an important and challenging issue in fault-tolerant multi-domain optical networks. In this paper, we study protection algorithms in multi-domain optical networks and propose a new heuristic algorithm called multi-domain Hamiltonian cycle protection (MHCP) to tolerate the single-fiber link failure. In MHCP, we present the local Hamiltonian cycle (LHC) method based on the physical Topology of each single-domain and the global Hamiltonian cycle (GHC) method based on the abstracted Virtual Topology of multi-domains to protect the intra-fiber link and inter-fiber link failures, respectively. We also present the link-cost formulas to encourage the load balancing and proper links selection for computing the working path of each connection request. Simulation results show that, compared with previous multi-domain protection algorithm, MHCP can obtain better performances in resource utilization ratio, blocking probability, and computation complexity.
Zhiquan Luo - One of the best experts on this subject based on the ideXlab platform.
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reconfiguration with no service disruption in multifiber wdm networks
Journal of Lightwave Technology, 2005Co-Authors: Mohamed Saad, Zhiquan LuoAbstract:In a wavelength division multiplexing (WDM)-based network, lightpaths are established between router pairs to form a Virtual Topology residing on top of the underlying physical Topology. The ability to reconfigure its Virtual Topology upon dynamically changing traffic patterns has been identified as one of the most important features of WDM-based networks. Given a multifiber WDM network with limited fiber and wavelength resources, an existing Virtual Topology, and a new set of traffic demands, this paper addresses the problem of finding the new Virtual Topology that maximizes the carried traffic of connections, while absolutely guaranteeing that ongoing connections are not disrupted. We introduce conditions under which the new Virtual Topology has the intrinsic property of no service disruption. Then, we use these conditions to formulate the reconfiguration problem as an integer linear program (ILP). We also present a heuristic reconfiguration algorithm that is based on partitioning the traffic demands, so as to maintain wavelength loads as balanced as possible, followed by solving a sequence of single-wavelength problems. We theoretically verify the correctness of the algorithm, and illustrate its efficiency in terms of solution quality and computational cost via numerical experiments.
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reconfiguration with no service disruption in multifiber wdm networks based on lagrangean decomposition
International Conference on Communications, 2003Co-Authors: Mohamed Saad, Zhiquan LuoAbstract:In a WDM based network, lightpaths are established between router pairs to form a Virtual Topology residing on top of the underlying physical Topology. The ability to reconfigure its Virtual Topology upon dynamically changing traffic patterns has been identified as one of the most important features of WDM based networks. Compared to previously reported reconfiguration studies, we provide contributions along two different directions. First, we address the problem of finding the new Virtual Topology that maximizes the number of successfully established lightpaths, while guaranteeing absolutely no service disruptions. Second, based on a Lagrangean decomposition approach, we demonstrate that optimal and near-optimal Virtual topologies can be obtained by considering only one wavelength in the formulation, leading to a reconfiguration algorithm that scales to an arbitrarily large number of wavelengths. Computational results confirm the high efficiency of the proposed algorithm.
