Shared-Risk Logical Span Groups in Span-Restorable Optical Networks: Analysis and Capacity Planning Model

International audienceThe notion of Shared Risk Link Groups (SRLG) has been introduced to capture surviv-ability issues where some links of a network fail simultaneously. In this context, the k-diverse routing problem is to find a set of k pairwise SRLG-disjoint paths between a given pair of end nodes of the network. This problem has been proven NP-complete in general and some polynomial instances have been characterized. In this paper, we investigate the k-diverse routing problem in networks where the SRLGs are localized and satisfy the star property. This property states that a link may be subject to several SRLGs, but all links subject to a given SRLG are incident to a common node. We first provide counterexamples to the polynomial time algorithm proposed by X. Luo and B. Wang (DRCN'05) for computing a pair of SRLG-disjoint paths in networks with SRLGs satisfying the star property, and then prove that this problem is in fact NP-complete. We then characterize instances that can be solved in polynomial time or are fixed parameter tractable, in particular when the number of SRLGs is constant, the maximum degree of the vertices is at most 4, and when the network is a directed acyclic graph. Finally we consider the problem of finding the maximum number of SRLG-disjoint paths in networks with SRLGs satisfying the star property. We prove that this problem is NP-hard to approximate within O(|V | 1−ε) for any 0 < ε < 1, where V is the set of nodes in the network. Then, we provide exact and approximation algorithms for relevant subcases

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“…In [13] (see also [27,Chapter 11.4.2,) it has been shown that MSP is W [1]-hard if the parameter is the number of disjoint subsets. 2…”

Section: Parameterized Complexitymentioning

confidence: 99%

Finding disjoint paths in networks with star shared risk link groups

Bermond

Coudert

D’Angelo

et al. 2015

Theoretical Computer Science

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“…Various approaches to path provisioning, and more specifically routing and wavelength assignment (RWA) in optical networks containing SRLGs have been studied [11], [12], [13], [14] with the common goal of avoiding the failure of working and spare path at the same time. RWA problem can be expressed as an integer linear program.…”

Section: Related Workmentioning

confidence: 99%

Impact evaluation of physical length of shared risk link groups on optical network availability using Monte Carlo simulation

Miletić

Mikac

Džanko

2013

Proceedings of the 2013 18th European Conference on Network and Optical Communications &Amp; 2013 8th Conference on Optical Cab

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In optical networks a group of logically distinct links can unintentionally share a physical resource (e.g. a cable or a duct). Such a group, called shared risk link group (SRLG), introduces a situation where a single failure of common resource can cause multiple failures. Failure of common resource usually occurs due to physical force (e.g. digging or earthquake) and causes failures of multiple links. Specifically, such a failure can cause both working and spare wavelength path of a logical connection between two edge nodes to fail at the same time, leaving them disconnected until a repair is done. The usual approach to solving this problem consists of introducing more spare capacity to the network and also using a routing algorithm that takes SRLGs into account when computing paths. Such a routing algorithm avoids creating working and spare path pairs that have links contained in the same SRLG, to minimize the negative impact of SRLG failure on logical connection availability. In this paper the impact of physical length of the SRLGs on network availability is evaluated using Monte Carlo simulation. New simulation model for availability evaluation is implemented by discrete-event network simulator ns-3. Implementation approach is discussed, and an overview of model features is provided. For simple cases, Monte Carlo simulation results obtained by using the model are compared to analytical results. The availability results for the general case are obtained using Monte Carlo simulation and discussed.

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“…It can also represent links that are located in the same seismic area, or radio links in access and backhaul networks subject to localized environmental conditions affecting signal transmission, or traffic jam propagation in road networks. In practice the failures are localized and very common SRLGs are star SRLGs or SRLGs verifying the star property [7] (coincident SRLGs in [5]). Under this property, a link can be affected by more than one risk but all links of any SRLG share an endpoint.…”

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confidence: 99%

Diverse routing in networks with star SRLGs

Bermond

Coudert

D’Angelo

et al. 2012

Proceedings of the 2012 ACM Conference on CoNEXT Student Workshop

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The notion of Shared Risk Link Group, SRLG has been introduced to capture multiple correlated failures in a network. A SRLG is a set of links that fail simultaneously if a given event (risk) occurs. In such multiple failures scenario, the problem of Diverse Routing consists in finding two SRLGdisjoint paths between a pair of nodes. We consider such problem for localized failures, when all the links of a SRLG verify the star property i.e. when they are incident to the same node. We prove that in this case the problem is in general NP-complete and determine some polynomial cases.

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Shared-Risk Logical Span Groups in Span-Restorable Optical Networks: Analysis and Capacity Planning Model

Cited by 14 publications

References 11 publications

Finding disjoint paths in networks with star shared risk link groups

Finding disjoint paths in networks with star shared risk link groups

Impact evaluation of physical length of shared risk link groups on optical network availability using Monte Carlo simulation

Diverse routing in networks with star SRLGs

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