The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
Krishna M. Sivalingam - One of the best experts on this subject based on the ideXlab platform.
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INFOCOM - Routing, wavelength and time-slot assignment in time division multiplexed wavelength-routed optical WDM networks
Proceedings.Twenty-First Annual Joint Conference of the IEEE Computer and Communications Societies, 2002Co-Authors: Krishna M. SivalingamAbstract:We study routing and wavelength assignment for a circuit-switched time division multiplexed (TDM) wavelength-routed (WR) optical WDM network. In a conventional WR network, an entire wavelength is assigned to a given Session (or circuit). This can lead to lower channel utilization when the individual Sessions do not need the entire channel bandwidth. We consider a TDM-based approach to reduce this inefficiency. In this architecture, each wavelength is partitioned in the time-domain into fixed-length time-slots organized as a TDM frame. Multiple Sessions are multiplexed on each wavelength by assigning a sub-set of the TDM slots to each Session. Thus, given a Session Request with a specified bandwidth, the goal is to determine the route, wavelength and time-slot assignment (RWTA) that meets the Request. This is similar to routing and wavelength assignment in WR networks. We present a family of RWTA algorithms and study the blocking performance. We use the existing shortest-path routing algorithm with a new link cost function, least resistance weight (LRW) function, that incorporates wavelength utilization information. We employ the known least loaded (LL) wavelength selection and present three variations of the least-loaded time-slot (LLT) algorithm. Simulation based analyses are used to compare the proposed TDM architecture to traditional WR networks, both with and without wavelength conversion. The goal is to compare the benefits of TDM and wavelength conversion towards improving performance in WR networks. The results show that the use of TDM provides substantial gains, especially for multi-fiber networks.
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Routing, wavelength and time-slot assignment in time division multiplexed wavelength-routed optical WDM networks
Proceedings.Twenty-First Annual Joint Conference of the IEEE Computer and Communications Societies, 2002Co-Authors: Bo Wen, Krishna M. SivalingamAbstract:We study routing and wavelength assignment for a circuit-switched time division multiplexed (TDM) wavelength-routed (WR) optical WDM network. In a conventional WR network, an entire wavelength is assigned to a given Session (or circuit). This can lead to lower channel utilization when the individual Sessions do not need the entire channel bandwidth. We consider a TDM-based approach to reduce this inefficiency. In this architecture, each wavelength is partitioned in the time-domain into fixed-length time-slots organized as a TDM frame. Multiple Sessions are multiplexed on each wavelength by assigning a sub-set of the TDM slots to each Session. Thus, given a Session Request with a specified bandwidth, the goal is to determine the route, wavelength and time-slot assignment (RWTA) that meets the Request. This is similar to routing and wavelength assignment in WR networks. We present a family of RWTA algorithms and study the blocking performance. We use the existing shortest-path routing algorithm with a new link cost function, least resistance weight (LRW) function, that incorporates wavelength utilization information. We employ the known least loaded (LL) wavelength selection and present three variations of the least-loaded time-slot (LLT) algorithm. Simulation based analyses are used to compare the proposed TDM architecture to traditional WR networks, both with and without wavelength conversion. The goal is to compare the benefits of TDM and wavelength conversion towards improving performance in WR networks. The results show that the use of TDM provides substantial gains, especially for multi-fiber networks.
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Routing Mechanisms Employing Adaptive Weight Functions for Shortest Path Routing in Optical WDM Networks
Photonic Network Communications, 2001Co-Authors: N. Bhide, Krishna M. Sivalingam, T. Fabry-asztalosAbstract:Optical dense wavelength division multiplexed (DWDM) networks are an attractive candidate for the next generation Internet and beyond. In this paper, we consider routing and wavelength assignment in a wide area wavelength routed backbone network that employs circuit-switching. When a Session Request is received by the network, the routing and wavelength assignment (RWA) task is to establish a lightpath between the source and destination. That is, determine a suitable path and assign a set of wavelengths for the links on this path. We consider a link state protocol approach and use Dijkstra’s shortest path algorithm, suitably modified for DWDM networks, for computing the shortest paths. In [1] we proposed WDM aware weight functions that included factors such as available wavelengths per link, total wavelengths per link. In this paper, we present new weight functions that exploit the strong correlation between blocking probability and number of hops involved in connection setup to increase the performance of the network. We also consider alternate path routing that computes the alternate paths based on WDM aware weight functions. The impact of the weight functions on the blocking probability and delay is studied through discrete event simulation. The system parameters varied include number of network nodes, wavelengths, degree of wavelength conversion, and load. The results show that the weight function that incorporates both hop count and available wavelength provides the best performance in terms of blocking probability.
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ICC (3) - Adaptive weight functions for shortest path routing algorithms for multi-wavelength optical WDM networks
2000 IEEE International Conference on Communications. ICC 2000. Global Convergence Through Communications. Conference Record, 2000Co-Authors: T. Fabry-asztalos, N. Bhide, Krishna M. SivalingamAbstract:Optical dense wavelength division multiplexed (DWDM) networks are an attractive candidate for the next generation Internet and beyond. In this paper, we consider the wide area wavelength routed backbone network with circuit-switching. Given a Session Request, the routing and wavelength assignment (RWA) problem is to calculate a path between two nodes, and also assign a set of wavelengths along this path. We use Dijkstra's shortest path algorithm, suitably modified for DWDM networks, for computing the shortest paths. We consider WDM aware weight functions which include factors such as available wavelengths per link, distance, and total wavelengths per link. We study and compare the performance of these weight functions in terms of blocking probability, link utilization and average delay.
Ashok Jhunjhunwala - One of the best experts on this subject based on the ideXlab platform.
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Load balanced routing to enhance the performance of optical backbone networks
2008 5th IFIP International Conference on Wireless and Optical Communications Networks (WOCN '08), 2008Co-Authors: P Rajalakshmi, Ashok JhunjhunwalaAbstract:In this paper, we identify the topological and routing technique constraints on the performance of optical backbone WDM networks with wavelength conversion at the nodes and propose techniques to over come this constraints so that the network performance is enhanced. For any Session Request, a lightpath has to be established on the shortest path between the node pairs. As each lightpath is a substantial revenue and long-lived, the network operator would like no lightpath Request rejection (call blocking) or would like to accommodate more calls in the network before he has to upgrade his network. Hence given a network, we are proposing an analytical method to identify the critical links of the network which will cause early blocking, for the fixed shortest path routing. Once the critical links are identified, we would like to analyse the physical location of these critical links on the network topology and propose a new fixed routing technique namely, restricted routing by which the performance is enhanced as it balances the load uniformly among the links. In this routing technique, not all the calls have the shortest path. We compare the performance of the restricted routing with the optimal performance where all the links have equal blocking probability. The analysis is carried out on some of the standard backbone networks and the results show that by the restricted routing there is a significant performance improvement.
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Routing wavelength and time-slot reassignment algorithms for TDM based optical WDM networks
Computer Communications, 2007Co-Authors: Pachamuthu Rajalakshmi, Ashok JhunjhunwalaAbstract:In this paper, we consider the problem of maximizing the time of first lightpath Request rejection, T in the circuit-switched time division multiplexed (TDM) wavelength-routed (WR) optical WDM networks. TDM is incorporated into WDM, to increase the channel utilization when the carried traffic does not require the entire channel bandwidth. In TDM-WDM network, multiple Sessions are multiplexed on each wavelength by assigning a sub-set of the TDM slots to each Session. Thus, given a Session Request with a specified bandwidth, a lightpath has to be established by using the routing, wavelength and time-slot assignment (RWTA) algorithms. If the lightpath cannot be established, lightpath Request rejection or call blocking occurs. As each lightpath is substantial revenue and long-lived, lightpath Request rejection is highly unfavourable in the optical backbone networks. In this paper, we are proposing an intelligent routing, wavelength and time-slot reassignment algorithm for multi-rate traffic demands, where, when a call gets blocked, the already established calls in the network are rerouted, wavelength and time-slot reassigned so as to accommodate the blocked call. Since we are talking of slow arrivals and long holding times for the lightpaths, it is possible to do this reassignment while provisioning a new call. Simulation based analyses are used to study the performance of the proposed reassignment algorithm. The results show that the proposed reassignment algorithm can be used to maximize the time of first call blocking, thereby accommodating more calls in the network before upgrading the network capacity.
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Wavelength reassignment algorithms for all-optical WDM backbone networks
Optical Switching and Networking, 2007Co-Authors: Pachamuthu Rajalakshmi, Ashok JhunjhunwalaAbstract:In this paper, we consider the problem of enhancing the blocking performance, in the circuit-switched wide-area optical wavelength-division multiplexed (WDM) networks with no wavelength conversion at the nodes. The limitation of such a no conversion network is the wavelength continuity constraint (wcc) which requires the same wavelength on all the hops of the path. Whenever there is a Session Request, a lightpath has to be established in the network. If the lightpath could not be established, lightpath Request rejection or call blocking occurs. As each lightpath is a substantial revenue and is long-lived, lightpath Request rejection is highly unfavorable in the optical backbone networks. An optimal optical network is the one with wavelength conversion capability at the nodes. In these conversion networks, blocking occurs due to capacity exhaustion on the links and not due to wcc. Hence these networks have the lowest possible blocking probability (Pb) achievable for any given network. Our aim is to see if one can achieve this near optimal blocking performance in no conversion networks by using our proposed wavelength reassignment algorithms. In the reassignment technique, when the new call gets blocked due to wcc, the already established calls or lightpaths are wavelength reassigned, so as to create a wavelength-continuous route in order to accommodate the new call. During wavelength reassignment, the routes for all the calls remain the same, i.e. no rerouting is done. We have proposed two heuristic reassignment algorithms namely, MOLC and Random and have studied their performance on some standard backbone optical networks. Simulation results show that in these example networks, our proposed reassignment algorithm can mostly remove the blocking due to the wcc and can achieve the wavelength conversion performance.
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ICON - Routing Wavelength and Timeslot Reassignment Algorithms for TDM based Optical WDM Networks - Multi rate traffic demands
2006 14th IEEE International Conference on Networks, 2006Co-Authors: Pachamuthu Rajalakshmi, Ashok JhunjhunwalaAbstract:In this paper, we consider the problem of maximizing the time of first lightpath Request rejection, T in the circuit-switched time division multiplexed (TDM) wavelength-routed (WR) optical WDM networks. TDM is incorporated into WDM, to increase the channel utilization when the carried traffic does not require the entire channel bandwidth. In TDM-WDM network, multiple Sessions are multiplexed on each wavelength by assigning a sub-set of the TDM slots to each Session. Thus, given a Session Request with a specified bandwidth, a lightpath has to be established by using the routing, wavelength and time-slot assignment (RWTA) algorithms. If the lightpath cannot be established, lightpath Request rejection or call blocking occurs. As each lightpath is substantial revenue and long-lived, lightpath Request rejection is highly unfavourable in the opitcal backbone networks. In this paper, we are proposing an intelligent routing, wavelength and time-slot reassignment algorithm for multi rate traffic demands, where, when a call gets blocked, the already established calls in the network are rerouted, wavelength and timeslot reassigned so as to accomodate the blocked call. Since we are talking of slow arrivals and long holding times for the lightpaths, it is possible to do this reassignment while provisioning a new call. Simulation based analyses are used to study the performance of the proposed reassignment algorithm. The results show that the proposed reassignment algorithm can be used to maximize the time of first call blocking, thereby accommodating more calls in the network before upgrading the network capacity.
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Routing Wavelength and Timeslot Reassignment Algorithms for TDM based Optical WDM Networks - Multi rate traffic demands
2006 14th IEEE International Conference on Networks, 2006Co-Authors: P Rajalakshmi, Ashok JhunjhunwalaAbstract:In this paper, we consider the problem of maximizing the time of first lightpath Request rejection, T in the circuit-switched time division multiplexed (TDM) wavelength-routed (WR) optical WDM networks. TDM is incorporated into WDM, to increase the channel utilization when the carried traffic does not require the entire channel bandwidth. In TDM-WDM network, multiple Sessions are multiplexed on each wavelength by assigning a sub-set of the TDM slots to each Session. Thus, given a Session Request with a specified bandwidth, a lightpath has to be established by using the routing, wavelength and time-slot assignment (RWTA) algorithms. If the lightpath cannot be established, lightpath Request rejection or call blocking occurs. As each lightpath is substantial revenue and long-lived, lightpath Request rejection is highly unfavorable in the optical backbone networks. In this paper, we are proposing an intelligent routing, wavelength and time-slot reassignment algorithm for multi rate traffic demands, where, when a call gets blocked, the already established calk in the network are rerouted, wavelength and timeslot reassigned so as to accommodate the blocked call. Since we are talking of slow arrivals and long holding times for the lightpaths, it is possible to do this reassignment while provisioning a new call. Simulation based analyses are used to study the performance of the proposed reassignment algorithm. The results show that the proposed reassignment algorithm can be used to maximize the time of first call blocking, thereby accommodating more calls in the network before upgrading the network capacity
Bo Wen - One of the best experts on this subject based on the ideXlab platform.
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Routing, wavelength and time-slot assignment in time division multiplexed wavelength-routed optical WDM networks
Proceedings.Twenty-First Annual Joint Conference of the IEEE Computer and Communications Societies, 2002Co-Authors: Bo Wen, Krishna M. SivalingamAbstract:We study routing and wavelength assignment for a circuit-switched time division multiplexed (TDM) wavelength-routed (WR) optical WDM network. In a conventional WR network, an entire wavelength is assigned to a given Session (or circuit). This can lead to lower channel utilization when the individual Sessions do not need the entire channel bandwidth. We consider a TDM-based approach to reduce this inefficiency. In this architecture, each wavelength is partitioned in the time-domain into fixed-length time-slots organized as a TDM frame. Multiple Sessions are multiplexed on each wavelength by assigning a sub-set of the TDM slots to each Session. Thus, given a Session Request with a specified bandwidth, the goal is to determine the route, wavelength and time-slot assignment (RWTA) that meets the Request. This is similar to routing and wavelength assignment in WR networks. We present a family of RWTA algorithms and study the blocking performance. We use the existing shortest-path routing algorithm with a new link cost function, least resistance weight (LRW) function, that incorporates wavelength utilization information. We employ the known least loaded (LL) wavelength selection and present three variations of the least-loaded time-slot (LLT) algorithm. Simulation based analyses are used to compare the proposed TDM architecture to traditional WR networks, both with and without wavelength conversion. The goal is to compare the benefits of TDM and wavelength conversion towards improving performance in WR networks. The results show that the use of TDM provides substantial gains, especially for multi-fiber networks.
Tanmay De - One of the best experts on this subject based on the ideXlab platform.
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CISIM - A Cost Efficient Multicast Routing and Wavelength Assignment in WDM Mesh Network
Communications in Computer and Information Science, 2020Co-Authors: Subhendu Barat, Ashok Kumar Pradhan, Tanmay DeAbstract: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.
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ICIT - Multicast Routing and Spectrum Assignment in Flexible-Grid Optical Networks Based on Light-Tree Sharing Approach
2016 International Conference on Information Technology (ICIT), 2016Co-Authors: Panchali Datta Choudhury, Ritesh Singh Chauhan, P. V. Sudheer, Tanmay DeAbstract:Studies on Flexible-Grid technology reveals that it provides desirable solution for next generation high-speed network design. Multicast Routing and Spectrum assignment (MRSA) in Flexible-Grid Optical Networks (alternately Elastic Optical Networks) generates a multicast tree for each multicast Session Request and spectrum frequency slots are allocated to each of the edge of the multicast tree. Orthogonal Frequency Division Multiplexing (OFDM) technique can be used to implement MRSA algorithm. Spectrum frequency slots are allocated to the edges of the multicast tree obeying the spectrum continuity constraint and spectrum contiguity constraint, thus creating a multicast light-tree. In this paper we have proposed a lighttreesharing based multicast routing and spectrum assignment technique. Similar multicast Requests are grouped together and their bandwidth requirements are added up. For each multicast Session Request a layered auxiliary graph is selected based on available spectrum in the network and the Request's bandwidth demand. An efficient light-tree is generated from this auxiliary graph, first for the clubbed Request and then for the individual Requests separately. The simulation results show that our proposed algorithm significantly reduce the average tree size and increases number of Requests satisfied than the well-known existing algorithm mentioned in literature. Incidentally the average number of splitters required is also reduced.
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Multicast Routing and Spectrum Assignment in Flexible-Grid Optical Networks Based on Light-Tree Sharing Approach
2016 International Conference on Information Technology (ICIT), 2016Co-Authors: Panchali Datta Choudhury, Ritesh Singh Chauhan, P. V. Sudheer, Tanmay DeAbstract:Studies on Flexible-Grid technology reveals that it provides desirable solution for next generation high-speed network design. Multicast Routing and Spectrum assignment (MRSA) in Flexible-Grid Optical Networks (alternately Elastic Optical Networks) generates a multicast tree for each multicast Session Request and spectrum frequency slots are allocated to each of the edge of the multicast tree. Orthogonal Frequency Division Multiplexing (OFDM) technique can be used to implement MRSA algorithm. Spectrum frequency slots are allocated to the edges of the multicast tree obeying the spectrum continuity constraint and spectrum contiguity constraint, thus creating a multicast light-tree. In this paper we have proposed a lighttreesharing based multicast routing and spectrum assignment technique. Similar multicast Requests are grouped together and their bandwidth requirements are added up. For each multicast Session Request a layered auxiliary graph is selected based on available spectrum in the network and the Request's bandwidth demand. An efficient light-tree is generated from this auxiliary graph, first for the clubbed Request and then for the individual Requests separately. The simulation results show that our proposed algorithm significantly reduce the average tree size and increases number of Requests satisfied than the well-known existing algorithm mentioned in literature. Incidentally the average number of splitters required is also reduced.
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A load balanced approach of multicast routing and wavelength assignment in WDM networks
International Journal of Communication Networks and Distributed Systems, 2015Co-Authors: Subhendu Barat, Tanmay DeAbstract:Multicast routing and wavelength assignment MRWA deals with the problem of one-to-many communication in a wavelength division multiplexed optical fibre networks. As physical optical networks are equipped with finite number of optical channels in each fibre cable, throughput of the network is treated as a major performance issue. The aim of this work is to maximise throughput in a finite wavelength WDM network. As to establish multicast Session a single message may need to split into multiple messages fanning out of a node, the node must contain costly splitters. This work also considers the cost of splitting at the split nodes while establishing a light-tree for a particular multicast Session Request. Here a load-balancing technique is used to optimise the optical channel requirements to establish a multicast connection. The algorithm proposed here is compared with standard all-shortest path algorithm combined with first-fit wavelength assignment for multicasting by simulation on various network topologies and different network configurations. The simulation result shows that our proposed algorithm performs much better than the standard one.
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A genetic algorithm for multicasting in resource constraint WDM mesh networks
2012 IEEE 7th International Conference on Industrial and Information Systems (ICIIS), 2012Co-Authors: Subhendu Barat, Ashok Kumar Pradhan, Tanmay DeAbstract:Multicast Routing and Wavelength Assignment (MRWA) in WDM mesh network is a vital problem in one-to-many communication in photonic domain. The majority of works done in this problem is based on different heuristics. In this paper we have formulated the problem as a delay controlled splitting minimization problem and applied a genetic algorithm to provide a near optimal solution for multicasting in WDM mesh network. The major contribution in this paper is that we have taken multiple objectives in account including QoS parameter like delay and network resource parameters like splitters, optical channels while generating light-tree for each multicast Session Request. Here we have designed a novel tunable fitness function which provides efficient solution for MRWA problem with multiple conflicting objectives in a constrained setup. The simulation results establish the truth of this claim significantly.
R.g. Gallager - One of the best experts on this subject based on the ideXlab platform.
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Architectural study of high-speed networks with optical bypassing
2020Co-Authors: P. Saengudomlert, E.h. Modiano, R.g. GallagerAbstract:We study the routing and wavelength assignment (RWA) problem in wavelength division multiplexing (WDM) networks with no wavelength conversion. In a high-speed core network, the traffic can be separated into two components. The first is the aggregated traffic from a large number of small-rate users. Each individual Session is not necessarily static but the combined traffic streams between each pair of access nodes are approximately static. We support this traffic by static provisioning of routes and wavelengths. In particular, we develop several off-line RWA algorithms which use the minimum number of wavelengths to provide l dedicated wavelength paths between each pair of access nodes for basic all-to-all connectivity. The topologies we consider are arbitrary tree, bidirectional ring, two-dimensional torus, and binary hypercube topologies. We observe that wavelength converters do not decrease the wavelength requirement to support this uniform all-to-all traffic. The second traffic component contains traffic Sessions from a small number of large-rate users and cannot be well approximated as static due to insufficient aggregation. To support this traffic component, we perform dynamic provisioning of routes and wavelengths. Adopting a nonblocking formulation, we assume that the basic traffic unit is a wavelength, and the traffic matrix changes from time to time but always belongs to a given traffic set. More specifically, let N be the number of access nodes, and k denote an integer vector [k1, k 2,…, kN]. We define the set of k-allowable traffic matrices to be such that, in each traffic matrix, node i, 1 ≤ i ≤ N, can transmit at most ki wavelengths and receive at most ki wavelengths. We develop several on-line RWA algorithms which can support all the k-allowable traffic matrices in a rearrangeably nonblocking fashion while using close to the minimum number of wavelengths and incurring few rearrangements of existing lightpaths, if any, for each new Session Request. The topologies we consider are the same as for static provisioning. We observe that the number of lightpath rearrangements per new Session Request is proportional to the maximum number of lightpaths supported on a single wavelength. In addition, we observe that the number of lightpath rearrangements depends on the topological properties, e.g. network size, but not on the traffic volume represented by k as we increase k by some integer factor. Finally, we begin exploring an RWA problem in which traffic is switched in bands of wavelengths rather than individual wavelengths. We present some preliminary results based on the star topology. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)
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On-line routing and wavelength assignment for dynamic traffic in WDM ring and torus networks
IEEE ACM Transactions on Networking, 2006Co-Authors: P. Saengudomlert, E.h. Modiano, R.g. GallagerAbstract:We develop on-line routing and wavelength assignment (RWA) algorithms for WDM bidirectional ring and torus networks with N nodes. The algorithms dynamically support all k-allowable traffic matrices, where k denotes an arbitrary integer vector [k/sub 1/, k/sub 2/,... k/sub N/], and node i, 1 /spl les/ i /spl les/ N, can transmit at most k/sub i/ wavelengths and receive at most k/sub i/ wavelengths. Both algorithms support the changing traffic in a rearrangeably nonblocking fashion. Our first algorithm, for a bidirectional ring, uses [(/spl Sigma//sub i=1//sup N/ k/sub i/)/3] wavelengths in each fiber and requires at most three lightpath rearrangements per new Session Request regardless of the number of nodes N and the amount of traffic k. When all the k/sub i/'s are equal to k, the algorithm uses [kN/3] wavelengths, which is known to be the minimum for any off-line rearrangeably nonblocking algorithm. Our second algorithm, for a torus topology, is an extension of a known off-line algorithm for the special case with all the k/sub i/'s equal to k. For an R /spl times/ C torus network with R /spl ges/ C nodes, our on-line algorithm uses [kR/2] wavelengths in each fiber, which is the same as in the off-line algorithm, and is at most two times a lower bound obtained by assuming full wavelength conversion at all nodes. In addition, the on-line algorithm requires at most C - 1 lightpath rearrangements per new Session Request regardless of the amount of traffic k. Finally, each RWA update requires solving a bipartite matching problem whose time complexity is only O (R), which is much smaller than the time complexity O(kCR/sup 2/) of the bipartite matching problem for an off-line algorithm.
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Dynamic wavelength assignment for WDM all-optical tree networks
IEEE ACM Transactions on Networking, 2005Co-Authors: P. Saengudomlert, E.h. Modiano, R.g. GallagerAbstract:We develop an on-line wavelength assignment (WA) algorithm for a wavelength-routed WDM tree network. The algorithm dynamically supports all k-port traffic matrices among N end nodes, where k denotes an integer vector [k/sub 1/...,k/sub N/] and end node i,1/spl les/i/spl les/N, can transmit at most k/sub i/ wavelengths and receive at most k/sub i/ wavelengths. Our algorithm is rearrangeably nonblocking, uses the minimum number of wavelengths, and requires at most d/sup */-1 lightpath rearrangements per new Session Request, where d/sup */ is the degree of the most heavily used node. We observe that the number of lightpath rearrangements per new Session Request does not increase as the amount of traffic k scales up by an integer factor. In addition, wavelength converters cannot reduce the number of wavelengths required to support k-port traffic in a tree network. We show how to implement our WA algorithm using a hybrid wavelength-routed/broadcast tree with only one switching node connecting several passive broadcast subtrees. Finally, using roughly twice the minimum number of wavelengths for a rearrangeably nonblocking WA algorithm, we can modify the WA algorithm to be strict-sense nonblocking.
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INFOCOM - On-line routing and wavelength assignment for dynamic traffic in WDM ring and torus networks
IEEE INFOCOM 2003. Twenty-second Annual Joint Conference of the IEEE Computer and Communications Societies (IEEE Cat. No.03CH37428), 2003Co-Authors: P. Saengudomlert, E.h. Modiano, R.g. GallagerAbstract:We develop on-line routing and wavelength assignment (RWA) algorithms for WDM bidirectional ring and torus networks with N nodes. The algorithms dynamically support all k-allowable traffic matrices, where k denotes an arbitrary integer vector [k/sub 1/, k /sub 2/, ..., k/sub N/], and node i, 1/spl les/i/spl les/N, can transmit at most k/sub i/ wavelengths and receive at most k/sub i/ wavelengths. Both algorithms support the changing traffic in a rearrangeably nonblocking fashion. Our first algorithm, for a bidirectional ring, uses /spl lceil/(/spl Sigma//sub i=1//sup N/k/sub i/)/3/spl rceil/ wavelengths in each ring direction and requires at most three lightpath rearrangements per new Session Request regardless of the number of nodes N and the amount of traffic k. When all the k/sub i/s are equal to k, the algorithm uses /spl lceil/kN/3/spl rceil/ wavelengths, which is known to be the minimum for any off-line rearrangeably nonblocking algorithm. Our second algorithm, for a torus topology, is designed for the special case with all the k/sub i/s equal to k. For a square torus network with N nodes, the algorithm uses /spl lceil/k/spl radic/N/2/spl rceil/ wavelengths in each fiber, which is shown to be at most two times a lower bound obtained by assuming full wavelength conversion at all nodes. In addition, the algorithm requires at most /spl radic/N-1 lightpath rearrangements per new Session Request regardless of the amount of traffic k.
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On-line routing and wavelength assignment for dynamic traffic in WDM ring and torus networks
IEEE INFOCOM 2003. Twenty-second Annual Joint Conference of the IEEE Computer and Communications Societies (IEEE Cat. No.03CH37428), 2003Co-Authors: P. Saengudomlert, E.h. Modiano, R.g. GallagerAbstract:We develop on-line routing and wavelength assignment (RWA) algorithms for WDM bidirectional ring and torus networks with N nodes. The algorithms dynamically support all k-allowable traffic matrices, where k denotes an arbitrary integer vector [k/sub 1/, k /sub 2/, ..., k/sub N/], and node i, 1/spl les/i/spl les/N, can transmit at most k/sub i/ wavelengths and receive at most k/sub i/ wavelengths. Both algorithms support the changing traffic in a rearrangeably nonblocking fashion. Our first algorithm, for a bidirectional ring, uses /spl lceil/(/spl Sigma//sub i=1//sup N/k/sub i/)/3/spl rceil/ wavelengths in each ring direction and requires at most three lightpath rearrangements per new Session Request regardless of the number of nodes N and the amount of traffic k. When all the k/sub i/s are equal to k, the algorithm uses /spl lceil/kN/3/spl rceil/ wavelengths, which is known to be the minimum for any off-line rearrangeably nonblocking algorithm. Our second algorithm, for a torus topology, is designed for the special case with all the k/sub i/s equal to k. For a square torus network with N nodes, the algorithm uses /spl lceil/k/spl radic/N/2/spl rceil/ wavelengths in each fiber, which is shown to be at most two times a lower bound obtained by assuming full wavelength conversion at all nodes. In addition, the algorithm requires at most /spl radic/N-1 lightpath rearrangements per new Session Request regardless of the amount of traffic k.
