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Minimizing Electronic Line Terminals for Automatic Ring Protection in General WDM Optical Networks
 IEEE Journal of Selected Area on Communications
, 2002
"... Automatic ring protection provides simple and rapid fault protection and restoration in telecommunication networks. To implement the automatic ring protection in general wavelengthdivision multiplexing (WDM) optical networks, the lightpaths are partitioned into groups each of which can be carried in ..."
Abstract

Cited by 16 (0 self)
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Automatic ring protection provides simple and rapid fault protection and restoration in telecommunication networks. To implement the automatic ring protection in general wavelengthdivision multiplexing (WDM) optical networks, the lightpaths are partitioned into groups each of which can be carried in a simple cycle of the underlying network. As the electronic line terminals are the dominant cost factor in the deployment of WDM optical networks, we study how to generate these partitions with minimum electronic line terminals. This optimization problem is NPhard. We develop two polynomialtime approximation algorithms, with performance guarantees between 1.5 and 1.6 and between 1.5 and 1 5+ , respectively. The second algorithm can be adapted, with the same performance guarantees, to the problem in which lightpaths are not prespecified and only the endpoints of each connection are given. Both algorithms can be easily adapted, with the same performance guarantees, to the problem in which only link protection is desired, and each group must be carried in a closed trail. The first algorithm matches and the second algorithm improves the approximation ratio obtained independently by Eilam et al. (2000).
Cycle Covering
 IN ACM SYMPOSIUM ON PARALLEL ALGORITHMS AND ARCHITECTURES SPAA
, 2001
"... This paper considers the design of a survivable WDM network based on covering the initial network with subnetworks, which are protected independently from each other. We focus on the case where the optical WDM network is a ring, there are requests between any pair of vertices and the covering i ..."
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Cited by 6 (2 self)
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This paper considers the design of a survivable WDM network based on covering the initial network with subnetworks, which are protected independently from each other. We focus on the case where the optical WDM network is a ring, there are requests between any pair of vertices and the covering is done with small cycles. This problem can be modelled as follows: Find a covering of the edges of a logical graph I (here the complete graph K n ) by subgraphs I k of a certain kind (here cycles C k of length k), such that, for each I k , there exists in the physical graph G (here C n ) a disjoint routing of the edges of I k . The aim is to minimize the number of subgraphs I k in the covering. We give optimal solutions for that problem.
Vertex Disjoint Routings of Cycles over Tori
, 2007
"... We study the problem of designing a survivable WDM network based on covering the communication requests with subnetworks that are protected independently from each other. We consider here the case when the physical network is T (n), a torus of size n by n, the subnetworks are cycles and the communic ..."
Abstract

Cited by 6 (0 self)
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We study the problem of designing a survivable WDM network based on covering the communication requests with subnetworks that are protected independently from each other. We consider here the case when the physical network is T (n), a torus of size n by n, the subnetworks are cycles and the communication scheme is alltoall or total exchange (where all pairs of vertices communicate). We will represent the communication requests by a logical graph: a complete graph for the scheme of alltoall. This problem can be modeled as follows: find a cycle partition or covering of the request edges of Kn2, such that for each cycle in the partition, its request edges can be routed in the physical network T (n) by a set of vertex disjoint paths (equivalently, the routings with the request cycle form an elementary cycle in T (n)). Let the load of an edge of the WDM network be the number of paths associated with the requests using the edge. The cost of the network depends on the total load (the cost of transmission) and the maximum load (the cost of equipment). To minimize these costs, we will search for an optimal (or quasi optimal) routing satisfying the following two conditions: (a) each request edge is routed by a shortest path over T (n), and (b) the load of each physical edge resulting from the routing of all cycles of S is uniform or quasi uniform. In this paper, we find a covering or partition of the request edges of K n 2 into cycles with an associated optimal or quasi optimal routing such that either (1) the number of cycles of the covering is minimum, or (2) the cycles have size 3 or 4.
Lightpath Arrangement in Survivable Rings to Minimize the Switching Cost
"... Abstract—This paper studies the design of lowcost survivable wavelengthdivisionmultiplexing (WDM) networks. To achieve survivability, lightpaths are arranged as a set of rings. Arrangement in rings is also necessary to support SONET/SDH protection schemes such as 4FBLSR above the optical layer. T ..."
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Abstract—This paper studies the design of lowcost survivable wavelengthdivisionmultiplexing (WDM) networks. To achieve survivability, lightpaths are arranged as a set of rings. Arrangement in rings is also necessary to support SONET/SDH protection schemes such as 4FBLSR above the optical layer. This is expected to be the most common architecture in regional (metro) networks [9]. We assume that we are given a set of lightpaths in an arbitrary network topology and aim at finding a partition of the lightpaths to rings adding a minimum number of lightpaths to the original set. The cost measure that we consider (number of lightpaths) reflects the switching cost of the entire network. In the case of a SONET/SDH higher layer, the number of lightpaths is equal to the number of adddrop multiplexers (ADMs) (since two subsequent lightpaths in a ring can share an ADM at the common node). We prove some negative results on the tractability and approximability of the problem and provide an approximation algorithm with a worst case approximation ratio of 8/5. We study some special cases in which the performance of the algorithm is improved. A similar problem was introduced, motivated, and studied in [9] and recently in [13] (where it was termed minimum ADM problem). However, these two works focused on a ring topology while we generalize the problem to an arbitrary network topology. Index Terms—Optical network design, SONET add/drop multiplexers (ADMs), SONET rings, wavelengthdivision multiplexing (WDM).
A Note on Cycle Covering (Extended Abstract)
"... This study considers the design of a survivable WDM network based on covering the initial network with subnetworks, which are protected independently from each other. ..."
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This study considers the design of a survivable WDM network based on covering the initial network with subnetworks, which are protected independently from each other.