Fragmentation Problems and Management Approaches in Elastic Optical Networks: A Survey

Chatterjee, Bijoy Chand; Ba, Seydou; Oki, Eiji

doi:10.1109/comst.2017.2769102

Cited by 178 publications

(110 citation statements)

References 111 publications

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“…We tested for three connection load scenarios: elastic, the 4-7-12 rule, and the 2-5-8 rule. In the case of elastic, the connection load is in the range of [2,15] FSs, including guardband, while the rule 4-7-12 describes the scenario of three distinct services with requirements of 4 FSs, 7 FSs, and 12 FSs, including guardbands. 15 The 2-5-8 rule is found to improve FF performance by restricting the allowed connection size to 2, 5, or 8 FSs.…”

Section: Performance Evaluationmentioning

confidence: 99%

“…The main focus of routing and spectrum allocation assignment (RSA) EON algorithms is that connections must satisfy both the continuity and frequency contiguity constraints …”

Section: Introductionmentioning

confidence: 99%

“…The main focus of routing and spectrum allocation assignment (RSA) EON algorithms is that connections must satisfy both the continuity and frequency contiguity constraints. 2,3 Our work addresses the fairness problem that multihop connections face, specifically that connections comprising many hops suffer from a larger BP compared to those over fewer hops, as satisfying the continuity and contiguity constraint over longer distances becomes increasingly harder. Thus, we propose a new metric in this paper, the normalized to hop-distance bandwidth blocking probability (normalized_BBP) that considers connection hop distance and its effect on network performance.…”

Section: Introductionmentioning

confidence: 99%

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Hop distance–based bandwidth allocation technique for elastic optical networks

Mavridopoulos

Beletsioti

Nicopolitidis

et al. 2020

Int J Communication

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Summary Elastic optical networks (EON) have emerged as a solution to the growing needs of the future internet, by allowing for greater flexibility, spectrum efficiency, and scalability, when compared to WDM solutions. EONs achieve those improvements through finer spectrum allocation granularity. However, due to the continuity and contiguity constrains, distant connections that are routed through multiple hops suffer from increased bandwidth blocking probability (BBP), while more direct connections are easier to form. This paper proposes HopWindows, a novel method that strategically allocates bandwidth to connections based on their hop distance. This new algorithm applies masks that control the range of frequency slots (FSs) allocated to each n‐hop connection. Furthermore, a new network metric is introduced, the normalized bandwidth blocking probability (normalized BBP). Utilization of this metric ensures increased fairness to distant connections. Extended simulation results are presented which indicate that the proposed HopWindows method achieves a superior performance over the well‐known FirstFit algorithm. The proposed algorithm may achieve a decrease in bandwidth blocking probability of up to 50%.

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Section: Performance Evaluationmentioning

confidence: 99%

“…The main focus of routing and spectrum allocation assignment (RSA) EON algorithms is that connections must satisfy both the continuity and frequency contiguity constraints …”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hop distance–based bandwidth allocation technique for elastic optical networks

Mavridopoulos

Beletsioti

Nicopolitidis

et al. 2020

Int J Communication

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show abstract

“…In SS-FONs, setting up and tearing down dynamic requests may result in spectrum fragmentation. When spectrum becomes fragmented, available resources are divided into small free spectral intervals, which are unlikely to be utilized by future requests and may increase blocking [5,6]. A key issue in SS-FONs is spatial continuity constraint (SCC), i.e., the constraint that a unique spatial mode shall be assigned to all the channels along a lightpath.…”

Section: Introductionmentioning

confidence: 99%

“…First, we propose several new fragmentation metrics tailored for SS-FONs. Note that, while various fragmentation metrics have been proposed for classical EONs (i.e., without SDM) [5], our study is the first one, to the best of our knowledge, to investigate fragmentation metrics in SS-FONs. Second, we introduce the concept of bordering super-channels (B-SChs), i.e., SChs whose spectrum is at the "border" of already allocated spectrum slots with the intent of minimizing spectrum waste, and hence, fragmentation.…”

Section: Introductionmentioning

confidence: 99%

Fragmentation metrics and fragmentation-aware algorithm for spectrally/spatially flexible optical networks

Lechowicz

Tornatore

Włodarczyk

et al. 2020

J. Opt. Commun. Netw.

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Spectrally/spatially-flexible optical networks (SS-FONs) are a promising solution to cope with future traffic requirements in optical backbone networks. SS-FONs exploit the spatial dimension to increase network capacity while preserving resource management flexibility, as they still operate within a flex-grid composed of small frequency slots (slices). Flex-grid allows realizing transmission using super-channels (SChs) that comprise a set of contiguous slots. In this paper, we focus on spectral SChs, i.e., a SCh realized only on one spatial mode on each fiber. In SS-FONs, setting up and tearing down multiple lightpath requests within flex-grid may result in spectrum fragmentation, and, in turn, blocking of requests. In this work, we investigate several fragmentation metrics in SS-FON. The problem of identifying appropriate metrics to measure fragmentation has been investigated in single-core elastic optical networks (EONs), but, to the best of our knowledge, there is lack of such investigation for SS-FONs. Therefore, we propose several fragmentation metrics for SS-FON. We introduce the concept of bordering super-channels (B-SChs), i.e., SChs whose spectrum is allocated at the "border" of already allocated spectrum slots that are promising SChs to be chosen to minimize fragmentation. The investigation of all candidate B-SCh for a request allows us to find the one which minimizes network fragmentation, and, in turn spectrum waste. Hence, we propose a fragmentation-aware algorithm with bordering super-channels (FA-BSC) that assigns optical resources to dynamic requests utilizing information from the proposed fragmentation metrics and the set of candidate B-SChs. Experiments on a representative network topology show that the investigation of multiple B-SChs in the fragmentation-aware algorithm reduces the blocking probability when compared to the reference fragmentation-aware algorithms. Finally, we analyze the impact of a spatial continuity constraint on the network fragmentation.

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Post‐Disaster least loaded lightpath routing in elastic optical networks

Ashraf

Idrus

Butt

et al. 2019

Int J Communication

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SummaryDisaster events directly affect the physical topology of core networks and may lead to simultaneous failure of multiple lightpaths leading to massive service outages for network operators. To recover from such a failure scenario, the existing routing algorithms running on network nodes (routers or switches) typically attempt to reestablish the connections over new routes with shortest distances and hop count approach. However, this approach may result in congestion on some links, while other links may have the unutilized capacity. Hence, intelligent lightpath computing techniques are required to efficiently route network traffic over the new routes by considering traffic load of each link in addition to distance and hop count to minimize network congestion. In this paper, we have proposed a capacity‐constrained maximally spatial disjoint lightpath algorithm to tackle the provisioning and restoration of disrupted lightpaths in a postdisaster scenario in the context of elastic optical networking. This algorithm computes an alternate least loaded lightpath for disrupted primary lightpath using capacity‐constrained shortest lightpath. Alternate lightpath selection is based on a criteria parameter for a lightpath to be least loaded and constrained by either the length or the spatial distance between primary and alternate lightpaths. The spatial distance between lightpaths enables to reestablish the disrupted connection request away from disaster proximity. The performance of the proposed algorithm is evaluated through simulation for several parameters like blocking probability, network utilization, connection success rates, and minimum spatial distance.

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Fragmentation Problems and Management Approaches in Elastic Optical Networks: A Survey

Cited by 178 publications

References 111 publications

Hop distance–based bandwidth allocation technique for elastic optical networks

Hop distance–based bandwidth allocation technique for elastic optical networks

Fragmentation metrics and fragmentation-aware algorithm for spectrally/spatially flexible optical networks

Post‐Disaster least loaded lightpath routing in elastic optical networks

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