Alternate Routing

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Sheng-wei Wang - One of the best experts on this subject based on the ideXlab platform.

  • lightpath level active reRouting algorithms in all optical wdm networks with Alternate Routing and traffic grooming
    International Conference on Information Networking, 2012
    Co-Authors: Sheng-wei Wang, Chinyen Wen
    Abstract:

    This paper proposes two lightpath-level active reRouting algorithms, namely, the least resources reRouting algorithm and the load balanced reRouting algorithm, in all-optical WDM networks with Alternate Routing and traffic grooming. The proposed algorithms consist of three major components to be determined: i) when the reRouting algorithm initiates, ii) which lightpath is rerouted, and iii) which Routing path and wavelength for the rerouted lightpath is newly allocated. The proposed active reRouting algorithms initiate the reRouting procedure when a connection leaves and a lightpath is released. The lightpath to be rerouted is selected according to the objectives of two different algorithms. The Routing path and wavelength allocated to the rerouted lightpath is that the departure connection released. Simulation results show that the proposed load-balanced active reRouting algorithm yields much lower connection blocking probability than the least resources reRouting algorithms. We also observe that the number of rerouted lightpaths is very small. This result implies that the overhead for reRouting a lightpath is small and the performance of the networks can be significantly improved.

  • Probability based dynamic-Alternate Routing and the corresponding converter placement algorithm in all-optical WDM networks
    Computer Networks, 2012
    Co-Authors: Sheng-wei Wang
    Abstract:

    This paper proposes a new dynamic-Alternate Routing algorithm and its corresponding converter placement algorithm in order to reduce the connection blocking probability for all-optical WDM networks. The main idea in the proposed dynamic-Alternate Routing algorithm is to try to route the traffics according to a predefined optimal probability distribution. The problem for finding the optimal probability distribution was shown as a convex optimization problem. The problem can be solved by flow deviation method or other standard optimization techniques. Simulation results show that the proposed Routing algorithm yields lower connection blocking probabilities than the previous works. The proposed Routing algorithm produces similar traffic pattern as the optimal traffic pattern. The similarity between the traffic pattern produced by the proposed dynamic-Alternate Routing algorithm and the optimal traffic pattern can be further employed for solving other network designing problems such as converter placement problem. Since the optimal traffic pattern can be easily predicted, the optimal traffic pattern which minimizes the blocked traffic intensity is utilized for finding the locations of wavelength converters. The key idea is to place the wavelength converters at the nodes where they are needed most. Simulations have been performed to study the performance of the proposed wavelength converter placement method. The simulation results have shown that the proposed placement method combined with the proposed probability based dynamic-Alternate Routing algorithm yields smaller connection blocking probability than the two converter placement methods with their corresponding Alternate Routing algorithms.

  • Probability based dynamic-Alternate Routing algorithm in all-optical WDM networks
    2011
    Co-Authors: Sheng-wei Wang
    Abstract:

    This paper proposes a new dynamic-Alternate Routing algorithm for all-optical WDM networks without wavelength conversion in order to reduce the connection blocking probability. The main idea in the proposed dynamic-Alternate Routing algorithm is to try to route the traffics according to a predefined optimal probability distribution. The problem for finding the optimal probability distribution has been shown as a convex optimization problem. The problem can be solved by flow deviation method or other standard optimization techniques. The simulation results show that the proposed Routing algorithm yields lower connection blocking probabilities than the previous works as well as the proposed Routing algorithm produces similar traffic pattern as the optimal traffic pattern. The similarity between the traffic pattern produced by the proposed dynamic-Alternate Routing algorithm and the optimal traffic pattern can be further used for solving other network designing problems.

  • Allocation of Wavelength Converters in All-Optical WDM Networks with Alternate Routing
    2010
    Co-Authors: Sheng-wei Wang
    Abstract:

    This paper proposes a wavelength converter placement method such that the same network will yield low connection blocking probability even when the Alternate Routing algorithm is replaced by a different one. Since the objective of the Alternate Routing algorithms used in the networks is to minimize blocking probability, the optimal traffic pattern which minimize the blocked traffic intensity is utilized for finding the locations of wavelength converters. The key idea is to place the wavelength converters at the nodes where they are needed most. Simulations have been performed to study the performance of the proposed wavelength converter placement method. The simulation results have shown that the proposed placement method yields smaller connection blocking probability than the two converter placement methods when the networks employ the hop count based fixedAlternate Routing or least-loaded Routing.

  • Finding Routing Paths for Alternate Routing in All-Optical WDM Networks
    Journal of Lightwave Technology, 2008
    Co-Authors: Hwa-chun Lin, Sheng-wei Wang, Meng-lin Hung
    Abstract:

    An Alternate Routing algorithm requires a set of predetermined Routing paths between each source-destination pair. To reduce the connection blocking probability, it is desirable that the predetermined Routing paths between each source-destination pair be link-disjoint. The predetermined Routing paths used in previous works on Alternate Routing are the -shortest link-disjoint paths in terms of hop count. The shared links among the -shortest link-disjoint paths between different source-destination pairs may cause high connection blocking probability. Thus, depending on the traffic requirements of all source-destination pairs, hop-count based -shortest link-disjoint paths may not be the best choice for the predetermined Routing paths. This paper proposes a method to find a set of link-disjoint Routing paths between each source-destination pair to be used by an Alternate Routing algorithm in order to reduce the connection blocking probability. The key idea is to find a set of link-disjoint Routing paths based on the Routing paths that are utilized by the optimal traffic pattern in the network. Then, for each source-destination pair, we select a set of link-disjoint Routing paths from the Routing paths that are utilized by the optimal traffic pattern such that the selected set of link-disjoint Routing paths carries the most of the traffic between the source-destination pair. Simulations are performed to compare the performance of using the link-disjoint Routing paths found by the proposed method as the predetermined Routing paths and those of using the hop-count based -shortest link-disjoint paths and employing the Routing paths found by the capacity-balanced Alternate Routing method proposed method by Ho and Mouftah (in 2002) as the predetermined Routing paths. Our simulation results show that using the link-disjoint Routing paths found by the proposed method yields significantly lower connection blocking probability than employing the hop-count based -shortest link-disjoint paths and using the Routing paths found by the capacity-balanced Alternate Routing method (Ho and Mouftah, 2002).

Hussein T. Mouftah - One of the best experts on this subject based on the ideXlab platform.

  • localized power aware Alternate Routing for wireless ad hoc networks
    Communications and Mobile Computing, 2009
    Co-Authors: Baoxian Zhang, Hussein T. Mouftah, Zhuang Zhao
    Abstract:

    In this paper, we design a localized power-aware Alternate Routing (LPAR) protocol for dynamic wireless ad hoc networks. The design objective is to prolong the lifetime of wireless ad hoc networks wherein nodes can adaptively adjust their transmission power based on communication ranges. LPAR achieves this goal via two phases. In the first phase, energy draining balancing is achieved by identifying end-to-end paths with high residual energy. The second phase is designed to effectively reduce the power consumed for packet forwarding. This is achieved by iteratively performing adaptive localized power-aware Alternate reRouting to bypass each (potentially) high-power link along the end-to-end path identified in the first phase. Further, the design of LPAR enables nodes to collect their neighborhood information ‘on-demand’, which can effectively reduce the overhead for gathering such information. LPAR is suitable for both homogeneous and non-homogeneous networks. Simulation results demonstrate that LPAR achieves improved performance in reducing protocol overhead and also in prolonging network lifetime as compared with existing work. Copyright © 2008 John Wiley & Sons, Ltd.

  • an approach for enhancing fixed Alternate Routing in dynamic wavelength routed wdm networks
    Global Communications Conference, 2002
    Co-Authors: Hussein T. Mouftah
    Abstract:

    A novel planning algorithm, namely capacity-balanced Alternate Routing (C-BAR), is proposed for enhancing fixed Alternate Routing in dynamic wavelength-routed WDM networks. With C-BAR, Alternate paths between each source-destination (S-D) pair are defined at the network planning stage according to the load distribution and the location of each S-D pair, so that the Routing of lightpaths can take the most advantages of the load-balancing characteristic of the Alternate paths. A methodology for designing the number of Alternate paths between an S-D pair for achieving a specific performance requirement is demonstrated. Simulation is conducted to examine the proposed approaches, and show that the C-BAR algorithm can significantly improve the performance in blocking probability compared with the other reported RWA schemes.

  • dynamic reconfiguration based on balanced Alternate Routing algorithm bara for all optical wavelength routed wdm networks
    Global Communications Conference, 2002
    Co-Authors: Bin Zhou, Jun Zheng, Hussein T. Mouftah
    Abstract:

    This paper studies the virtual topology reconfiguration problem for all-optical wavelength-routed WDM networks. We consider dynamic reconfiguration in response to changing traffic demands and formulate the problem as an Integer Programming problem with multiple optimization objectives, aiming at maximizing the network throughput, minimizing the average propagation delay over a lightpath, and minimizing the reconfiguration cost. We use heuristics to obtain approximate optimal solutions and propose a balanced Alternate Routing algorithm (BARA) based on a genetic algorithm. To make the problem computational tractable, we assume wavelength converters at each network node and approximately divide the optimization process into two relatively independent stages: route computation and lightpath Routing. At the route computing stage, the aim is to compute a set of Alternate routes for each pair of source and destination nodes in the network. At the lightpath Routing stage, the aim is to decide an "optimal" route for each of the lightpaths between a pair of source and destination nodes from a set of Alternate routes, and the decisions are subject to the formulated constraints and optimization objectives. Through simulation experiments, we show the effectiveness of BARA.

  • capacity balanced Alternate Routing for mpls traffic engineering
    International Symposium on Computers and Communications, 2002
    Co-Authors: Hussein T. Mouftah
    Abstract:

    This paper solves the problem of path selection for connection-oriented MPLS-based mesh networks with a special focus on implementation issues in middle-sized networks, such as metropolitan-area networks (MANs). A novel network planning algorithm, called capacity-balanced Alternate Routing (C-BAR), is proposed. For C-BAR, Alternate paths between each ingress-egress pair are defined at a network planning stage according to the network topology and potential traffic load and location of each ingress-egress pair so that load-balancing can be achieved in Routing label switched paths (LSPs). Both analytical and simulation-based studies have been conducted to examine the proposed approach. The results show that the C-BAR algorithm can significantly improve the performance in blocking probability by spreading potential traffic to the whole network compared with other reported connection-oriented Routing schemes.

  • spare capacity planning using survivable Alternate Routing for long haul wdm networks
    International Symposium on Computers and Communications, 2002
    Co-Authors: Bin Zhou, Hussein T. Mouftah
    Abstract:

    Spare capacity planning is designed to find the minimum amount of spare capacity to be allocated throughout a network so that the network can survive from network component failures. In this paper, the spare capacity planning problem is investigated for long-haul wavelength division multiplexing (WDM) networks. A three-step method is developed for solving the problem. First, heuristic approaches are used to select both candidate working routes and protection routes in order to achieve approximate optimal performance while maintaining a computational feasibility. Second, traffic requests are distributed on the obtained candidate working and protection routes optimally using genetic algorithms (GA). Finally wavelengths are assigned to working lightpaths and shared protection lightpaths. The major advantage of the new approach is the ability to incorporate nonlinear constraints and nonlinear cost functions into the GA, which are introduced by sharing protection links between shared risk link groups (SRLG). Moreover, by considering SRLG constraints in the spare capacity planning phase, wavelengths can be allocated to each shared protection route before failures happen, so that shorter restoration latency can be achieved. Numerical results illustrate that the proposed approach is more cost-effective than the single-path protection method.

Meng-lin Hung - One of the best experts on this subject based on the ideXlab platform.

  • Finding Routing Paths for Alternate Routing in All-Optical WDM Networks
    Journal of Lightwave Technology, 2008
    Co-Authors: Hwa-chun Lin, Sheng-wei Wang, Meng-lin Hung
    Abstract:

    An Alternate Routing algorithm requires a set of predetermined Routing paths between each source-destination pair. To reduce the connection blocking probability, it is desirable that the predetermined Routing paths between each source-destination pair be link-disjoint. The predetermined Routing paths used in previous works on Alternate Routing are the -shortest link-disjoint paths in terms of hop count. The shared links among the -shortest link-disjoint paths between different source-destination pairs may cause high connection blocking probability. Thus, depending on the traffic requirements of all source-destination pairs, hop-count based -shortest link-disjoint paths may not be the best choice for the predetermined Routing paths. This paper proposes a method to find a set of link-disjoint Routing paths between each source-destination pair to be used by an Alternate Routing algorithm in order to reduce the connection blocking probability. The key idea is to find a set of link-disjoint Routing paths based on the Routing paths that are utilized by the optimal traffic pattern in the network. Then, for each source-destination pair, we select a set of link-disjoint Routing paths from the Routing paths that are utilized by the optimal traffic pattern such that the selected set of link-disjoint Routing paths carries the most of the traffic between the source-destination pair. Simulations are performed to compare the performance of using the link-disjoint Routing paths found by the proposed method as the predetermined Routing paths and those of using the hop-count based -shortest link-disjoint paths and employing the Routing paths found by the capacity-balanced Alternate Routing method proposed method by Ho and Mouftah (in 2002) as the predetermined Routing paths. Our simulation results show that using the link-disjoint Routing paths found by the proposed method yields significantly lower connection blocking probability than employing the hop-count based -shortest link-disjoint paths and using the Routing paths found by the capacity-balanced Alternate Routing method (Ho and Mouftah, 2002).

  • Traffic Intensity Based Alternate Routing for All-Optical WDM Networks
    Journal of Lightwave Technology, 2008
    Co-Authors: Hwa-chun Lin, Sheng-wei Wang, Chung-peng Tsai, Meng-lin Hung
    Abstract:

    This paper proposes a new approach to designing Alternate Routing algorithms for all-optical wavelength-division multiplexing networks in order to reduce the connection blocking probability. The key idea is to try to route traffic in approximately the optimal way of splitting the traffic among the multiple Routing paths between each source-destination pair. The optimal way of splitting the traffic among the multiple Routing paths between each source-destination pair is obtained by solving a nonlinear multicommodity flow optimization problem. Two Alternate Routing algorithms, namely, traffic intensity based fixed-Alternate Routing algorithm and traffic intensity based dynamic-Alternate Routing algorithm, are proposed based on this approach. Simulations are performed to study the performances of the proposed Alternate Routing algorithms. Our simulation results show that the Alternate Routing algorithms designed according to the optimal way of splitting the traffic can effectively reduce the connection blocking probability.

Hwa-chun Lin - One of the best experts on this subject based on the ideXlab platform.

  • Finding Routing Paths for Alternate Routing in All-Optical WDM Networks
    Journal of Lightwave Technology, 2008
    Co-Authors: Hwa-chun Lin, Sheng-wei Wang, Meng-lin Hung
    Abstract:

    An Alternate Routing algorithm requires a set of predetermined Routing paths between each source-destination pair. To reduce the connection blocking probability, it is desirable that the predetermined Routing paths between each source-destination pair be link-disjoint. The predetermined Routing paths used in previous works on Alternate Routing are the -shortest link-disjoint paths in terms of hop count. The shared links among the -shortest link-disjoint paths between different source-destination pairs may cause high connection blocking probability. Thus, depending on the traffic requirements of all source-destination pairs, hop-count based -shortest link-disjoint paths may not be the best choice for the predetermined Routing paths. This paper proposes a method to find a set of link-disjoint Routing paths between each source-destination pair to be used by an Alternate Routing algorithm in order to reduce the connection blocking probability. The key idea is to find a set of link-disjoint Routing paths based on the Routing paths that are utilized by the optimal traffic pattern in the network. Then, for each source-destination pair, we select a set of link-disjoint Routing paths from the Routing paths that are utilized by the optimal traffic pattern such that the selected set of link-disjoint Routing paths carries the most of the traffic between the source-destination pair. Simulations are performed to compare the performance of using the link-disjoint Routing paths found by the proposed method as the predetermined Routing paths and those of using the hop-count based -shortest link-disjoint paths and employing the Routing paths found by the capacity-balanced Alternate Routing method proposed method by Ho and Mouftah (in 2002) as the predetermined Routing paths. Our simulation results show that using the link-disjoint Routing paths found by the proposed method yields significantly lower connection blocking probability than employing the hop-count based -shortest link-disjoint paths and using the Routing paths found by the capacity-balanced Alternate Routing method (Ho and Mouftah, 2002).

  • Traffic Intensity Based Alternate Routing for All-Optical WDM Networks
    Journal of Lightwave Technology, 2008
    Co-Authors: Hwa-chun Lin, Sheng-wei Wang, Chung-peng Tsai, Meng-lin Hung
    Abstract:

    This paper proposes a new approach to designing Alternate Routing algorithms for all-optical wavelength-division multiplexing networks in order to reduce the connection blocking probability. The key idea is to try to route traffic in approximately the optimal way of splitting the traffic among the multiple Routing paths between each source-destination pair. The optimal way of splitting the traffic among the multiple Routing paths between each source-destination pair is obtained by solving a nonlinear multicommodity flow optimization problem. Two Alternate Routing algorithms, namely, traffic intensity based fixed-Alternate Routing algorithm and traffic intensity based dynamic-Alternate Routing algorithm, are proposed based on this approach. Simulations are performed to study the performances of the proposed Alternate Routing algorithms. Our simulation results show that the Alternate Routing algorithms designed according to the optimal way of splitting the traffic can effectively reduce the connection blocking probability.

  • traffic intensity based fixed Alternate Routing in all optical wdm networks
    International Conference on Communications, 2006
    Co-Authors: Hwa-chun Lin, Sheng-wei Wang, Chung-peng Tsai
    Abstract:

    This paper proposes a new fixed-Alternate Routing algorithm for all-optical WDM networks without wavelength conversion in order to reduce the connection blocking probability. The key idea in the proposed fixed-Alternate Routing algorithm is to try to route the traffics in approximately the optimal way. The multiple Routing paths between each source-destination pair are arranged and used in descending order according to the traffic intensities obtained by solving a nonlinear multicommodity flow optimization problem. It is well known that finding the connection blocking probability is a very difficult task. Therefore, an objective function closely related to the connection probability is devised and used to formulate a nonlinear multicommodity flow optimization problem. Simulations are performed to study the performance of the proposed fixed-Alternate Routing algorithm. Our simulation results show that sorting the Routing paths according to the optimally assigned traffic intensities in the proposed fixed-Alternate Routing algorithm can effectively reduce the connection blocking probability compared with sorting the Routing paths according to hop counts in a typical fixed-Alternate Routing algorithm. In general, in all-optical WDM networks, a connection request that goes through a longer path experiences higher connection blocking probability than a connection request that goes through a shorter path. This is known as the fairness problem. Our simulation results show that the proposed algorithm yields better fairness than a typical fixed-Alternate Routing algorithm.

  • ICC - Traffic Intensity Based Fixed-Alternate Routing in All-Optical WDM Networks
    2006 IEEE International Conference on Communications, 2006
    Co-Authors: Hwa-chun Lin, Sheng-wei Wang, Chung-peng Tsai
    Abstract:

    This paper proposes a new fixed-Alternate Routing algorithm for all-optical WDM networks without wavelength conversion in order to reduce the connection blocking probability. The key idea in the proposed fixed-Alternate Routing algorithm is to try to route the traffics in approximately the optimal way. The multiple Routing paths between each source-destination pair are arranged and used in descending order according to the traffic intensities obtained by solving a nonlinear multicommodity flow optimization problem. It is well known that finding the connection blocking probability is a very difficult task. Therefore, an objective function closely related to the connection probability is devised and used to formulate a nonlinear multicommodity flow optimization problem. Simulations are performed to study the performance of the proposed fixed-Alternate Routing algorithm. Our simulation results show that sorting the Routing paths according to the optimally assigned traffic intensities in the proposed fixed-Alternate Routing algorithm can effectively reduce the connection blocking probability compared with sorting the Routing paths according to hop counts in a typical fixed-Alternate Routing algorithm. In general, in all-optical WDM networks, a connection request that goes through a longer path experiences higher connection blocking probability than a connection request that goes through a shorter path. This is known as the fairness problem. Our simulation results show that the proposed algorithm yields better fairness than a typical fixed-Alternate Routing algorithm.

Harry G. Perros - One of the best experts on this subject based on the ideXlab platform.

  • Alternate Routing in Tandem Traffic-Groomed Optical Networks
    Journal of Networks, 2007
    Co-Authors: Alicia Nicki Washington, Harry G. Perros
    Abstract:

    Recent advances in telecommunication networks have allowed WDM to emerge as a viable solution to the ever-increasing demands of the Internet. Because these networks carry large amounts of traffic, Alternate Routing methods are designed in order to allow traffic to be properly re-routed from source to destination in the event of certain events, such as link blocking or failure. In this paper, we consider a tandem traffic-groomed optical network, modeled as a multi-level overflow system, where each level represents a wavelength between adjacent nodes. The queueing network is analyzed using a combination of methods. As will be shown, the decomposition method provides a good approximate analysis of large overflow systems supporting traffic from multiple sources.

  • performance analysis of traffic groomed optical networks employing Alternate Routing techniques
    International Teletraffic Congress, 2007
    Co-Authors: Nicki Washington, Harry G. Perros
    Abstract:

    Recent advances in telecommunication networks have allowed WDM to emerge as a viable solution to the ever-increasing demands of the Internet. In a wavelength-routed optical network, traffic is transported over lightpaths, which exclusively occupy an entire wavelength on each hop of the source-destination path. Because these networks carry large amounts of traffic, Alternate Routing methods are designed in order to allow traffic to be properly re-routed from source to destination in the event of certain events, such as link blocking or failure. In this paper, we consider a tandem traffic-groomed optical network, modeled as a multi-level overflow system, where each level represents a wavelength between adjacent nodes. The queueing network is analyzed using a combination of methods. As will be shown, the decomposition method provides a good approximate analysis of large overflow systems supporting traffic from multiple sources.

  • analysis of a traffic groomed optical network with Alternate Routing
    International Conference on Information Technology, 2007
    Co-Authors: Alicia Nicki Washington, Harry G. Perros
    Abstract:

    Advances in telecommunication networks have allowed WDM to emerge as a viable solution to the ever-increasing demands of the Internet. Because these networks carry large amounts of traffic, Alternate Routing methods are designed in order to allow traffic to be properly re-routed from source to destination in the event of certain events, such as link blocking or failure. In this paper, we consider a tandem traffic-groomed optical network, modeled as a multi-level overflow system, where each level represents a wavelength between adjacent nodes. The queueing network is analyzed using a combination of methods. As will be shown, the decomposition method provides a good approximate analysis of large overflow systems supporting traffic from multiple sources

  • ITNG - Analysis of a Traffic-Groomed Optical Network with Alternate Routing
    Fourth International Conference on Information Technology (ITNG'07), 2007
    Co-Authors: Alicia Nicki Washington, Harry G. Perros
    Abstract:

    Advances in telecommunication networks have allowed WDM to emerge as a viable solution to the ever-increasing demands of the Internet. Because these networks carry large amounts of traffic, Alternate Routing methods are designed in order to allow traffic to be properly re-routed from source to destination in the event of certain events, such as link blocking or failure. In this paper, we consider a tandem traffic-groomed optical network, modeled as a multi-level overflow system, where each level represents a wavelength between adjacent nodes. The queueing network is analyzed using a combination of methods. As will be shown, the decomposition method provides a good approximate analysis of large overflow systems supporting traffic from multiple sources