A Survey on Algorithmic Aspects of Virtual Optical Network Embedding for Cloud Networks
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paper_title: An overview of network virtualization and cloud network as a service

paper_content:

Cloud computing services delivery and consumption model is based on communication infrastructure network. The network serves as a linkage between the end-users consuming cloud services and the providers of data centers providing the cloud services. In addition, in large-scale cloud data centers, tens of thousands of compute and storage nodes are connected by a data center network to deliver a single-purpose cloud service. To this end, some questions could be raised, such as the following: How do network architectures affect cloud computing? How will network architecture evolve to support better cloud computing and cloud-based service delivery? What is the network's role in reliability, performance, scalability, and security of cloud computing? Should the network be a dumb transport pipe or an intelligent stack that is cloud workload aware? This paper focuses on the networking aspect in cloud computing and shall provide insights to these questions. Researchers can use this paper to accelerate their research on devising mechanisms for the following: i provisioning cloud network as a service and ii engineering network of data centers. Copyright © 2014 John Wiley & Sons, Ltd.
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paper_title: Virtual Network Embedding: A Survey

paper_content:

Network virtualization is recognized as an enabling technology for the future Internet. It aims to overcome the resistance of the current Internet to architectural change. Application of this technology relies on algorithms that can instantiate virtualized networks on a substrate infrastructure, optimizing the layout for service-relevant metrics. This class of algorithms is commonly known as "Virtual Network Embedding (VNE)" algorithms. This paper presents a survey of current research in the VNE area. Based upon a novel classification scheme for VNE algorithms a taxonomy of current approaches to the VNE problem is provided and opportunities for further research are discussed.
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paper_title: Survivable virtual infrastructure mapping with shared protection in transport software defined networks (T-SDNs)

paper_content:

We propose the first algorithm to embed virtual infrastructures with shared protection over T-SDNs. The algorithm optimizes network utilization by provisioning at least 20% more virtual infrastructures over physical substrates compared to the baseline algorithm.
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paper_title: Survivable virtual infrastructure mapping with dedicated protection in transport software-defined networks [Invited]

paper_content:

Efficiently mapping multiple virtual infrastructures (VIs) onto the same physical substrate with survivability is one of the fundamental challenges related to network virtualization in transport software-defined networks (T-SDNs). In this paper, we study the survivable VI mapping problem in T-SDNs with the objective of minimizing the VI request blocking probability. In particular, we address the subproblems of modulation selection and spectrum allocation in the process of provisioning optical channels to support virtual links, taking into consideration the optical layer constraints such as the transmission reach constraint and the spectral continuity constraint. We propose an auxiliary-graph-based algorithm, namely, parallel VI mapping (PAR), to offer dedicated protection against any single physical node or link failure. More specifically, the PAR algorithm can jointly optimize the assignments of mapping the primary and backup VIs by adopting the modified Suurballe algorithm to find the shortest pair of node-disjoint paths for each virtual link. Through extensive simulations, we demonstrate that the PAR algorithm can significantly reduce the VI request blocking probability and improve the traffic-carrying capacity of the networks, compared to the baseline sequential VI mapping approaches.
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paper_title: Elastic optical networking: a new dawn for the optical layer?

paper_content:

Optical networks are undergoing significant changes, fueled by the exponential growth of traffic due to multimedia services and by the increased uncertainty in predicting the sources of this traffic due to the ever changing models of content providers over the Internet. The change has already begun: simple on-off modulation of signals, which was adequate for bit rates up to 10 Gb/s, has given way to much more sophisticated modulation schemes for 100 Gb/s and beyond. The next bottleneck is the 10-year-old division of the optical spectrum into a fixed "wavelength grid," which will no longer work for 400 Gb/s and above, heralding the need for a more flexible grid. Once both transceivers and switches become flexible, a whole new elastic optical networking paradigm is born. In this article we describe the drivers, building blocks, architecture, and enabling technologies for this new paradigm, as well as early standardization efforts.
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paper_title: Virtual network provisioning over multi-line rate networks with fixed or flexible grid

paper_content:

Network virtualization is considered one of the key technologies to provide the flexibility and isolation that cloud computing services require. In this paper, new algorithms for efficient virtual network provisioning over muti-line rate networks, with fixed-grid and flexible grid, are proposed. Both algorithms aim at efficiently use the resources of the physical network by prioritizing the mapping of virtual links (instead of the virtual nodes) and mapping the virtual nodes located at the extreme of each virtual link in such a way that the closest possible physical nodes are selected to establish them. By means of simulation we evaluate the performance of the proposed algorithms with both fixed and flex-grid. We show the better blocking performance of flexible grid networks, the benefit of revisitation and that physical impairments of multi-line rate networks might be a dominant contribution to the blocking of 40/100 Gbps virtual networks.
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paper_title: Virtual network mapping for multicast services with max-min fairness of reliability

paper_content:

Network function virtualization (NFV) provides an effective way to reduce the network provider's cost by allowing multiple virtual networks (VNs) to share the underlying physical infrastructure. In the NFV environment, especially when supporting multicast services over the VNs, reliability is a critical requirement since the failure of one virtual node can cause the malfunction of multiple nodes that receive multicasting data from it. In this paper, we study for the first time to the best of our knowledge how to efficiently map VNs for multicast services over both general IP networks and orthogonal frequency division multiplexing (OFDM)-based elastic optical networks (EONs) while taking into consideration the max-min fairness in terms of reliability among distinct VNs. For general IP networks, we propose a mixed integer linear programming (MILP) model to determine the upper bound on the reliability with max-min fairness. In addition, an efficient heuristic, namely a reliability-aware genetic (RAG) algorithm, is developed to address reliable multicast VN mapping with a low computational complexity. By encoding multicast tree construction and link mapping into the process of path selection, taking into consideration the reliability with max-min fairness, and the networking reliability factors during mutation, RAG can globally optimize the reliability and fairness of all the multicast VN requests. For OFDM-based EONs, we extend the MILP (RAG) to optical-MILP [(O-MILP) optical RAG (O-RAG)] by considering the most efficient modulation format selection strategy, spectrum continuity, and conflict constraints. Through extensive simulations, we demonstrate that RAG (O-RAG) achieves close to the optimal reliability fairness with a much lower time complexity than the MILP (O-MILP) model. In particular, the path reliability-based mutation strategy in RAG (O-RAG) yields a significant performance improvement over other heuristic solutions in terms of reliability fairness, bandwidth (spectrum) consumption, and transmission delay.
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paper_title: Virtual optical network embedding considering mixed transparent and translucent virtual links

paper_content:

An intelligent virtual optical network embedding approach is proposed, which minimizes the network resource usage of each request. Both transparent and translucent virtual optical link embedding is considered as specifically required by virtual optical links.
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paper_title: Optical Network Design With Mixed Line Rates and Multiple Modulation Formats

paper_content:

With the growth of traffic volume and the emergence of various new applications, future telecom networks are expected to be increasingly heterogeneous with respect to applications supported and underlying technologies employed. To address this heterogeneity, it may be most cost effective to set up different lightpaths at different bit rates in such a backbone telecom mesh network employing optical wavelength-division multiplexing. This approach can be cost effective because low-bit-rate services will need less grooming (i.e., less multiplexing with other low-bit-rate services onto high-capacity wavelengths), while a high-bit-rate service can be accommodated directly on a wavelength itself. Optical networks with mixed line rates (MLRs), e.g., 10/40/100 Gb/s over different wavelength channels, are a new networking paradigm. The unregenerated reach of a lightpath depends on its line rate. So, the assignment of a line rate to a lightpath is a tradeoff between its capacity and transparent reach. Thus, based on their signal-quality constraints (threshold bit error rate), intelligent assignment of line rates to lightpaths can minimize the need for signal regeneration. This constraint on the transparent reach based on threshold signal quality can be relaxed by employing more advanced modulation formats, but with more investment. We propose a design method for MLR optical networks with transceivers employing different modulation formats. Our results demonstrate the tradeoff between a transceiver's cost and its optical reach in overall network design.
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paper_title: A sub-graph mapping-based algorithm for virtual network allocation over flexible grid networks

paper_content:

A new algorithm for dynamic network virtualization over flexible-grid networks is proposed. The algorithm, called Hamming-Fit, aims to map each request in a zone of the physical network resembling as much as possible the topology of the virtual network (sub-graph mapping). To do so, every possible node set (with as many nodes as the virtual network) of the physical topology is analyzed and its suitability evaluated using a metric analogous to the Hamming distance. In this way, a minimum usage of network resources is expected due to the use of 1-hop routes to establish the virtual links. The virtual link allocation also deals with the physical impairments of flexible grid networks by limiting the optical reach of the different optical signals and selectively adding guard bands when such optical reach must be surpassed. Simulation results show that Hamming-Fit exhibits a significant lower blocking than a previous proposal that uses exactly the same physical impairment model. The blocking improvement comes mainly from the fact that by performing a sub-graph mapping, shorter routes are used to map the virtual links. Thus, rejection due to the optical reach violation is minimized, which was the main drawback of the previous proposal.
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paper_title: Dynamic virtual network embedding scheme based on network element slicing for elastic optical networks

paper_content:

Dynamic virtual network embedding schemes based on Link Slicing (LS) and Node Slicing (NS) are proposed for elastic optical networks. Simulation results show that both LS and NS achieve better performance than baseline scheme in terms of blocking probability and revenue-to-cost ratio.
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paper_title: Migration based protection for virtual infrastructure survivability for link failure

paper_content:

We propose a new migratory protection scheme that maps a virtual infrastructure to a substrate network using minimal resources to recover from a single substrate link failure. The efficiency of our solution is shown using simulation.
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paper_title: Virtual concatenation-based elastic network embedding for inter-cloud-data-center networks

paper_content:

The elastic optical network (EON) provides fine-grained and orthogonal spectrum slots for the establishment of the elastic connection using orthogonal frequency division multiplexing (OFDM). Currently, the EON interconnection has realized the high-rate transmission among data centers (DCs). With the implementation of cloud DCs (CDCs) and EON virtualization, it becomes very essential to achieve the elastic network embedding (ENE) that facilitates the resource sharing in inter-cloud-data-center networks. The ENE operation consists of two components, the virtual-node mapping from virtual machine to CDC and the virtual-link (VL) mapping from virtual lightpath to fiber link(s). Thus an ENE request can be satisfied only when those two mapping processes have completed successfully. But during the VL mapping, some rigid constraints must be satisfied, such as the spectrum continuity, etc. This makes the ENE operation create the spectrum fragments over fiber links, which results in the denial of requests. Thus in this paper, we take the virtual concatenation (VC) into account when the VL mapping fails. The problem is formulated using the relaxed integer linear programming (ILP) model, and we also design a VC-based heuristic. Simulation results have verified the superiorities of the VC scheme on increasing the spectrum utilization and reducing the blocking rate of ENE requests.
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paper_title: Elastic optical networking: a new dawn for the optical layer?

paper_content:

Optical networks are undergoing significant changes, fueled by the exponential growth of traffic due to multimedia services and by the increased uncertainty in predicting the sources of this traffic due to the ever changing models of content providers over the Internet. The change has already begun: simple on-off modulation of signals, which was adequate for bit rates up to 10 Gb/s, has given way to much more sophisticated modulation schemes for 100 Gb/s and beyond. The next bottleneck is the 10-year-old division of the optical spectrum into a fixed "wavelength grid," which will no longer work for 400 Gb/s and above, heralding the need for a more flexible grid. Once both transceivers and switches become flexible, a whole new elastic optical networking paradigm is born. In this article we describe the drivers, building blocks, architecture, and enabling technologies for this new paradigm, as well as early standardization efforts.
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paper_title: Network virtualization over WDM networks

paper_content:

Network virtualization can eradicate the ossification of the Internet and stimulate innovation of new architectures and applications. Optical networks are ideal substrates for provisioning high-bandwidth virtual-network services. We investigate the problem of network virtualization over WDM networks by formulating a mixed integer linear program (MILP). Two heuristics, MaxMapping and MinMapping, are developed to solve the problem quickly but suboptimally. Numerical examples show that MinMapping consumes fewer wavelengths than MaxMapping and performs close to the optimal results of the MILP, by exploring the opportunities of traffic grooming.
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paper_title: Virtual network provisioning over multi-line rate networks with fixed or flexible grid

paper_content:

Network virtualization is considered one of the key technologies to provide the flexibility and isolation that cloud computing services require. In this paper, new algorithms for efficient virtual network provisioning over muti-line rate networks, with fixed-grid and flexible grid, are proposed. Both algorithms aim at efficiently use the resources of the physical network by prioritizing the mapping of virtual links (instead of the virtual nodes) and mapping the virtual nodes located at the extreme of each virtual link in such a way that the closest possible physical nodes are selected to establish them. By means of simulation we evaluate the performance of the proposed algorithms with both fixed and flex-grid. We show the better blocking performance of flexible grid networks, the benefit of revisitation and that physical impairments of multi-line rate networks might be a dominant contribution to the blocking of 40/100 Gbps virtual networks.
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paper_title: Virtual optical network composition over single-line-rate and mixed-line-rate WDM optical networks

paper_content:

Novel impairment and cost aware optical network virtualization mechanisms are investigated over single-line-rate and mixed-line-rate optical networks. Fundamental challenges are addressed by the proposed virtual optical network composition mechanisms utilizing optimization algorithms.
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paper_title: Virtual optical network embedding considering mixed transparent and translucent virtual links

paper_content:

An intelligent virtual optical network embedding approach is proposed, which minimizes the network resource usage of each request. Both transparent and translucent virtual optical link embedding is considered as specifically required by virtual optical links.
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paper_title: Performance modelling and analysis of dynamic virtual optical network composition

paper_content:

High-capacity networks based on optical technologies enable global delivery of high-performance network-based applications driven by Future Internet services. Due to the accelerated evolution of these applications, dynamic adaptability of the underlying optical infrastructure becomes crucial to support efficient data transport through the operators' networks. Optical network virtualization can be considered as a key technology for addressing this challenge. This paper presents a novel architecture enabled by optical network virtualization that adopts the concept of Infrastructure as a Service (IaaS). For the IaaS framework, three intelligent and dynamic composition mechanisms, employing Mixed Integer Linear Programming (MILP), K-Shortest Path (K-SP) and Random path routing algorithms are proposed. The performance of these algorithms in terms of the virtual optical network (VON) composition performance and the algorithm computational complexity is evaluated and compared in this study. The results show that MILP can provide optimal solutions for VON composition but it takes the longest time to execute, while the proposed Random algorithm can achieve the shortest running time.
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paper_title: Exploring Power-Efficient Provisioning for Online Virtual Network Requests

paper_content:

In the paradigm of cloud computing, multiple users can share the cloud infrastructure resources. The application or service requests from a user can be abstracted as a virtual network (VN) request and submitted to the cloud-based data centers. How to map a virtual network onto the cloud infrastructure network is a challenging issue in cloud resource provisioning. Current researches about virtual network mapping problem mainly focus on resource efficiency, which can be classified into resource efficient VN mapping or cost efficient VN mapping. However, the amount of power or energy consumed by data centers takes a large part of all of the power consumption. This may not only leads to a higher expenditure on the operation of data centers but also contribute to carbon emissions and the greenhouse effect. In this work we study the problem of power efficient virtual network mapping and propose a framework and algorithm for solving this problem. The simulation results show that our approach performs well.
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paper_title: Network Virtualization in Spectrum Sliced Elastic Optical Path Networks

paper_content:

The recent decade has witnessed an evolution toward virtualization of everything for the IT industry. Resources, from utility resources to networking components and functions, are abstracted as logical or virtual services. Virtualization results in elastic, agile, and automated resource provision, and facilitates the resource pricing in a pay-as-you-go model. Among this wave, the optical community has made parallel efforts in virtualizing resources in optical networks including both optical node and link resources. A virtualized optical network can not only seamlessly support automated resource provision, but also supply high-bandwidth any-to-any connectivity for network virtualization. In this paper, we overview the motivations and architecture for optical-based network virtualization. Among candidate optical networking paradigms, we argue that spectrum-sliced elastic optical path (SLICE) networks can be considered as a promising substrate choice, and study the key enabling problem, namely optical virtual network embedding over SLICE networks (OVNE-SLICE). We prove the NP-completeness of the OVNE-SLICE problem, and propose two mathematical models for this problem based on a concept named path-channel . The models are evaluated in our simulation, and compared with alternative models proposed in the literature.
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paper_title: Virtual optical network provisioning in flexible bandwidth optical networks

paper_content:

In order to address the virtual optical network (VON) provisioning problem, VON mapping approaches, which include the power-aware virtual links mapping (PVLM) approach and the power-aware virtual nodes mapping (PVNM) approach, are developed to reduce power consumption for a given set of VONs. Results show that our proposed mapping approach, PVLM, greatly reduces power consumption and saves spectrum resources compared to PVNM for different line rates and mixed line rate in flexible bandwidth optical networks.
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paper_title: Survivable impairment-constrained virtual optical network mapping in flexible-grid optical networks

paper_content:

In this paper, we study the problem of survivable impairment-constrained virtual optical network mapping in flexible-grid optical networks (SIC-VONM). The objective is to minimize the total cost of working and backup resources, including transponders, regenerators, and shared infrastructure, for a given set of virtual optical networks, which can survive single link failures. We first provide the problem definition of SIC-VONM, and then formulate the problem as an integer linear program (ILP). We also develop a novel heuristic algorithm, together with a baseline algorithm and a lower bound for comparison. Numerical results show that our proposed heuristic achieves results that are very close to those of the ILP for small-scale problems and that our proposed heuristic can solve large-scale problems very well.
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paper_title: Optimized PLI-aware virtual optical network composition

paper_content:

In this paper, a novel and optimized virtual optical network (VON) composition method, aware of the impact of physical layer impairments (PLIs), is investigated. VONs are composed using Mixed Integer Linear Programming (MILP), which can provide optimal solutions for VON composition. The quality of the composed VONs is verified by adopting an analytical assessment model of PLIs. In order to improve the performance of the PLI-aware VON composition with MILP, an optimization approach is proposed to integrate the two relatively independent phases, i.e. the VON composition and the quality verification of VON.
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paper_title: Virtual Optical Network Embedding (VONE) Over Elastic Optical Networks

paper_content:

Based on the concept of infrastructure as a service, optical network virtualization can facilitate the sharing of physical infrastructure among different users and applications. In this paper, we design algorithms for both transparent and opaque virtual optical network embedding (VONE) over flexible-grid elastic optical networks. For transparent VONE, we first formulate an integer linear programming (ILP) model that leverages the all-or-nothing multi-commodity flow in graphs. Then, to consider the continuity and consecutiveness of substrate fiber links' (SFLs') optical spectra, we propose a layered-auxiliary-graph (LAG) approach that decomposes the physical infrastructure into several layered graphs according to the bandwidth requirement of a virtual optical network request. With LAG, we design two heuristic algorithms: one applies LAG to achieve integrated routing and spectrum assignment in link mapping (i.e., local resource capacity (LRC)-layered shortest-path routing LaSP), while the other realizes coordinated node and link mapping using LAG (i.e., layered local resource capacity(LaLRC)-LaSP). The simulation results from three different substrate topologies demonstrate that LaLRC-LaSP achieves better blocking performance than LRC-LaSP and an existing benchmark algorithm. For the opaque VONE, an ILP model is also formulated. We then design a LRC metric that considers the spectrum consecutiveness of SFLs. With this metric, a novel heuristic for opaque VONE, consecutiveness-aware LRC-K shortest-path-first fit (CaLRC-KSP-FF), is proposed. Simulation results show that compared with the existing algorithms, CaLRC-KSP-FF can reduce the request blocking probability significantly.
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paper_title: Multicast service-oriented Virtual Network mapping over Elastic Optical Networks

paper_content:

Network Function Virtualization (NFV) allows multiple Virtual Networks (VNs) to share the underlying physical infrastructure via VN mapping, thus improving the utilization of physical resources. In this paper, for the first time, we study the multicast service-oriented VN mapping that can support big data applications over Elastic Optical Networks (EONs). Since the problem of minimizing the spectrum consumption in multicast service-oriented VN mapping is NP-hard, we propose an efficient heuristic algorithm, called Integrated Genetic and Simulated Annealing (IGSA) algorithm to address the problem with low computational complexity. By encoding node mapping, multicast tree construction, link mapping and spectrum requirements in the same gene and auto-adjusted evolution, and utilizing simulated annealing to find the fittest multicast requests mapping order, IGSA can perform joint optimization for all the multicast requests in a global way. Through extensive simulations, we demonstrate that IGSA outperforms the other heuristic solutions in terms of spectrum consumption, blocking probability and normalized throughput, while achieving close to minimum spectrum consumption with a much lower time complexity than MILP.
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paper_title: Cost-Efficient Virtual Optical Network Embedding for Manageable Inter-Data-Center Connectivity

paper_content:

Network virtualization opens the door to novel infrastructure services offering connectivity and node manageability. In this letter, we focus on the cost-efficient embedding of on-demand virtual optical network requests for interconnecting geographically distributed data centers. We present a mixed integer linear programming formulation that introduces flexibility in the virtual-physical node mapping to optimize the usage of the underlying physical resources. Illustrative results show that flexibility in the node mapping can reduce the number of add-drop ports required to serve the offered demands by 40%.
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paper_title: Improved approximation algorithms for unsplittable flow problems

paper_content:

In the single-source unsplittable flow problem we are given a graph G, a source vertex s and a set of sinks t/sub 1/, ..., t/sub k/ with associated demands. We seek a single s-t/sub i/ flow path for each commodity i so that the demands are satisfied and the total flow routed across any edge e is bounded by its capacity c/sub e/. The problem is an NP-hard variant of max flow and a generalization of single-source edge-disjoint paths with applications to scheduling, load balancing and virtual-circuit routing problems. In a significant development, Kleinberg gave recently constant-factor approximation algorithms for several natural optimization versions of the problem. In this paper we give a generic framework, that yields simpler algorithms and significant improvements upon the constant factors. Our framework, with appropriate subroutines applies to all optimization versions previously considered and treats in a unified manner directed and undirected graphs.
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paper_title: Survivable virtual infrastructure mapping with dedicated protection in transport software-defined networks [Invited]

paper_content:

Efficiently mapping multiple virtual infrastructures (VIs) onto the same physical substrate with survivability is one of the fundamental challenges related to network virtualization in transport software-defined networks (T-SDNs). In this paper, we study the survivable VI mapping problem in T-SDNs with the objective of minimizing the VI request blocking probability. In particular, we address the subproblems of modulation selection and spectrum allocation in the process of provisioning optical channels to support virtual links, taking into consideration the optical layer constraints such as the transmission reach constraint and the spectral continuity constraint. We propose an auxiliary-graph-based algorithm, namely, parallel VI mapping (PAR), to offer dedicated protection against any single physical node or link failure. More specifically, the PAR algorithm can jointly optimize the assignments of mapping the primary and backup VIs by adopting the modified Suurballe algorithm to find the shortest pair of node-disjoint paths for each virtual link. Through extensive simulations, we demonstrate that the PAR algorithm can significantly reduce the VI request blocking probability and improve the traffic-carrying capacity of the networks, compared to the baseline sequential VI mapping approaches.
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paper_title: Flexible virtual network provisioning over distance-adaptive flex-grid optical networks

paper_content:

We present a flexible virtual optical network provisioning procedure for distance-adaptive flex-grid optical networks. Simulations show ~3 times increase in effective network capacity by leveraging the combined effect of flexible node mapping and distance-adaptive modulation.
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paper_title: How to lease the internet in your spare time

paper_content:

Today's Internet Service Providers (ISPs) serve two roles: managing their network infrastructure and providing (arguably limited) services to end users. We argue that coupling these roles impedes the deployment of new protocols and architectures, and that the future Internet should support two separate entities: infrastructure providers (who manage the physical infrastructure) and service providers (who deploy network protocols and offer end-to-end services). We present a high-level design for Cabo, an architecture that enables this separation; we also describe challenges associated with realizing this architecture.
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paper_title: Scalable virtual network provisioning over distance-adaptive flexible grid optical networks

paper_content:

We propose a game theory based heuristic for provisioning virtual networks over distance-adaptive flexible grid optical networks. Our approach obtains close-to-optimal solutions with scalable and fast computation, which is critical for handling on-demand requests.
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paper_title: Virtual network mapping for multicast services with max-min fairness of reliability

paper_content:

Network function virtualization (NFV) provides an effective way to reduce the network provider's cost by allowing multiple virtual networks (VNs) to share the underlying physical infrastructure. In the NFV environment, especially when supporting multicast services over the VNs, reliability is a critical requirement since the failure of one virtual node can cause the malfunction of multiple nodes that receive multicasting data from it. In this paper, we study for the first time to the best of our knowledge how to efficiently map VNs for multicast services over both general IP networks and orthogonal frequency division multiplexing (OFDM)-based elastic optical networks (EONs) while taking into consideration the max-min fairness in terms of reliability among distinct VNs. For general IP networks, we propose a mixed integer linear programming (MILP) model to determine the upper bound on the reliability with max-min fairness. In addition, an efficient heuristic, namely a reliability-aware genetic (RAG) algorithm, is developed to address reliable multicast VN mapping with a low computational complexity. By encoding multicast tree construction and link mapping into the process of path selection, taking into consideration the reliability with max-min fairness, and the networking reliability factors during mutation, RAG can globally optimize the reliability and fairness of all the multicast VN requests. For OFDM-based EONs, we extend the MILP (RAG) to optical-MILP [(O-MILP) optical RAG (O-RAG)] by considering the most efficient modulation format selection strategy, spectrum continuity, and conflict constraints. Through extensive simulations, we demonstrate that RAG (O-RAG) achieves close to the optimal reliability fairness with a much lower time complexity than the MILP (O-MILP) model. In particular, the path reliability-based mutation strategy in RAG (O-RAG) yields a significant performance improvement over other heuristic solutions in terms of reliability fairness, bandwidth (spectrum) consumption, and transmission delay.
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paper_title: Survivable virtual optical network embedding with probabilistic network-element failures in elastic optical networks

paper_content:

Abstract The elastic optical networks can elastically allocate spectrum tailored for various bandwidth requirements. In addition, different virtual optical networks (VONs) formed by different applications or service providers need to be embedded on the common physical optical network, it brings virtual optical network embedding (VONE) problem. There is no precise standard to measure the survivability of VON from the failure probability view and take minimum VON failure probability as an objective in a VONE problem. In this paper, we investigate a survivable VONE problem from a new perspective. Considering probabilistic physical network-element failures, a novel metric, named virtual optical network failure probability (VON-FP), is introduced to evaluate the survivability of VONs in elastic optical networks. Moreover, a failure-probability-aware virtual optical network embedding (FPA-VONE) algorithm is proposed to deploy VONs on the physical network elements with small failure probability, and finally to decrease the VON-FP and enhance the spectrum utilization effectively.
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paper_title: A novel performance metric for Virtual Network Embedding combining aspects of Blocking Probability and Embedding Cost

paper_content:

Network Virtualization offers a solution for Future Internet and it is a key enabler for cloud computing applications. Virtual Network Embedding (VNE) problem deals with resource allocation of a physical infrastructure to Virtual Network Requests (VNRs). Several performance metrics are employed in order to evaluate the efficiency of specific VNE approaches. These existing metrics, mostly related to Infrastructure Provider profit, are computed at the end of the VNE process, after embedding many VNRs. This work proposes a novel performance metric, VNE-NP (VNE Normalized Profit) which combines aspects of the two metrics most used in the literature: Blocking Probability and Embedding Cost.
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paper_title: Impairment-aware optical network virtualization in single-line-rate and mixed-line-rate WDM networks

paper_content:

Optical network virtualization enables network operators to compose and operate multiple independent and application-specific virtual optical networks (VONs) sharing a common physical infrastructure. To achieve this capability, the virtualization mechanism must guarantee isolation between coexisting VONs. In order to satisfy this fundamental requirement, the VON composition mechanism must take into account the impact of physical layer impairments (PLIs). In this paper we propose a new infrastructure as a service architecture utilizing optical network virtualization. We introduce novel PLI-aware VON composition algorithms suitable for single-line-rate (SLR) and mixed-line-rate (MLR) network scenarios. In order to assess the impact of PLIs and guarantee the isolation of multiple coexisting VONs, PLI assessment models for intra- and inter-VON impairments are proposed and adopted in the VON composition process for both SLR and MLR networks. In the SLR networks, the PLI-aware VON composition mechanisms with both heuristic and optimal (MILP) mapping methods are proposed. A replanning strategy is proposed for the MILP mapping method in order to increase its efficiency. In the MLR networks, a new virtual link mapping method suitable for the MLR network scenario and two line rate distribution methods are proposed. With the proposed PLI-aware VON composition methods, multiple coexisting and cost-effective VONs with guaranteed transmission quality can be dynamically composed. We evaluate and compare the performance of the proposed VON composition methods through extensive simulation studies with various network scenarios.
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paper_title: Survivable impairment-constrained virtual optical network mapping in flexible-grid optical networks

paper_content:

In this paper, we study the problem of survivable impairment-constrained virtual optical network mapping in flexible-grid optical networks (SIC-VONM). The objective is to minimize the total cost of working and backup resources, including transponders, regenerators, and shared infrastructure, for a given set of virtual optical networks, which can survive single link failures. We first provide the problem definition of SIC-VONM, and then formulate the problem as an integer linear program (ILP). We also develop a novel heuristic algorithm, together with a baseline algorithm and a lower bound for comparison. Numerical results show that our proposed heuristic achieves results that are very close to those of the ILP for small-scale problems and that our proposed heuristic can solve large-scale problems very well.
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paper_title: Dynamic virtual network embedding over multilayer optical networks

paper_content:

Network virtualization is meant to improve the efficiency of network infrastructure by sharing a physical substrate network among multiple virtual networks. Virtual network embedding (VNE) determines how to map a virtual network request onto a physical substrate. In this paper, we first overview three possible underlying substrates for interdatacenter networks, namely an electrical-layer-based substrate, an optical-layer-based substrate, and a multilayer-based (optical and electrical layer) substrate. Then, the corresponding VNE problems for the three physical substrates are discussed. The work presented focuses on VNE over a multilayer optical network; a key problem is how to map a virtual network request onto either an electrical or optical substrate. We propose an auxiliary graph model to address multilayer virtual network mapping in a dynamic traffic scenario. Different node-mapping and link-mapping policies can be achieved by adjusting weights of the edges of the auxiliary graph, which depends on the purposes of the network operators.
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paper_title: Cost-Efficient Virtual Optical Network Embedding for Manageable Inter-Data-Center Connectivity

paper_content:

Network virtualization opens the door to novel infrastructure services offering connectivity and node manageability. In this letter, we focus on the cost-efficient embedding of on-demand virtual optical network requests for interconnecting geographically distributed data centers. We present a mixed integer linear programming formulation that introduces flexibility in the virtual-physical node mapping to optimize the usage of the underlying physical resources. Illustrative results show that flexibility in the node mapping can reduce the number of add-drop ports required to serve the offered demands by 40%.
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paper_title: A Cost Efficient Design of Virtual Infrastructures with Joint Node and Link Mapping

paper_content:

The virtualization of both servers and substrate networks is a promising technique that will enable the future Internet architecture to support a variety of cloud computing services and architectures. The problem of efficiently mapping a virtual infrastructure (VI) over a wide-area optical network is a key problem in provisioning Infrastructure (and Network) as a Service over multiple datacenters. In this paper, we study the problem of cost efficient VI mapping and propose a novel approach called the virtual infrastructure mapping algorithm (VIMA) that jointly considers node mapping and link mapping. Such a close coordination between the link and node mapping stages increases the efficiency of the VIMA algorithm. We compare the performance of our VIMA algorithm with other VI mapping algorithms such as NSVIM, vnmFlib and R-ViNE under various performance metrics using simulation. Our simulation results and analysis show that the VIMA algorithm outperforms the other algorithms in terms of VI mapping costs and path length of VI links.
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paper_title: Dynamic transparent virtual network embedding over elastic optical infrastructures

paper_content:

We propose a novel dynamic transparent virtual network embedding (VNE) algorithm, which considers node mapping and link mapping jointly, for network virtualization over optical orthogonal frequency-division multiplexing (O-OFDM) based elastic optical infrastructures. For each virtual optical network (VON) request, the algorithm first transfers the substrate optical network into a layered-auxiliary-graph according to the spectrum usage of each fiber link, then applies a node mapping approach that considers the local information of all substrate nodes, and accomplishes the link mapping, in a single layer of the auxiliary graph. The simulation results verify that the proposed algorithm considers the uniqueness of O-OFDM networks and outperforms two reference algorithms that directly apply the VNE schemes developed for Layer 2/3 or WDM network virtualization, by providing lower VON blocking probability. The simulations with a realistic topology also demonstrate that the average lengths of embedded substrate paths are well-controlled within the typical transmission reaches of O-OFDM signals. To the best of our knowledge, this is the first proposal that includes both link mapping and node mapping to address dynamic transparent VNE over elastic optical infrastructures.
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paper_title: Strategies for Virtual Optical Network Allocation

paper_content:

This paper presents Integer Linear Programming (ILP) formulations to optimally allocate Virtual Optical Networks (VONs) over a transparent optical network substrate. These formulations serve the purpose of building either completely transparent VONs or opaque ones, where electrical termination capabilities are assumed at each virtual network node. In addition, a lightweight Greedy Randomized Adaptive Search (GRASP) heuristic is provided for the transparent case. The obtained results validate the accuracy of the proposed heuristic and reveal the benefits of the presented solutions against simpler shortest-path-based VON allocation strategies.
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paper_title: Virtual Network Embedding: A Survey

paper_content:

Network virtualization is recognized as an enabling technology for the future Internet. It aims to overcome the resistance of the current Internet to architectural change. Application of this technology relies on algorithms that can instantiate virtualized networks on a substrate infrastructure, optimizing the layout for service-relevant metrics. This class of algorithms is commonly known as "Virtual Network Embedding (VNE)" algorithms. This paper presents a survey of current research in the VNE area. Based upon a novel classification scheme for VNE algorithms a taxonomy of current approaches to the VNE problem is provided and opportunities for further research are discussed.
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paper_title: RWA for network virtualization in optical WDM networks

paper_content:

We jointly consider problems of virtual network mapping and routing and wavelength assignment in WDM networks. Flexible virtual node mapping enabled by network virtualization achieves significant optical network resource savings compared to fixed node mapping.
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paper_title: Fault-tolerant virtual network mapping to provide Content Connectivity in optical networks

paper_content:

We define Content Connectivity as the reachability of every content from any point of an optical network. We propose a scheme for virtual network mapping and content placement to ensure content connectivity after failures.
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paper_title: Virtual network mapping for multicast services with max-min fairness of reliability

paper_content:

Network function virtualization (NFV) provides an effective way to reduce the network provider's cost by allowing multiple virtual networks (VNs) to share the underlying physical infrastructure. In the NFV environment, especially when supporting multicast services over the VNs, reliability is a critical requirement since the failure of one virtual node can cause the malfunction of multiple nodes that receive multicasting data from it. In this paper, we study for the first time to the best of our knowledge how to efficiently map VNs for multicast services over both general IP networks and orthogonal frequency division multiplexing (OFDM)-based elastic optical networks (EONs) while taking into consideration the max-min fairness in terms of reliability among distinct VNs. For general IP networks, we propose a mixed integer linear programming (MILP) model to determine the upper bound on the reliability with max-min fairness. In addition, an efficient heuristic, namely a reliability-aware genetic (RAG) algorithm, is developed to address reliable multicast VN mapping with a low computational complexity. By encoding multicast tree construction and link mapping into the process of path selection, taking into consideration the reliability with max-min fairness, and the networking reliability factors during mutation, RAG can globally optimize the reliability and fairness of all the multicast VN requests. For OFDM-based EONs, we extend the MILP (RAG) to optical-MILP [(O-MILP) optical RAG (O-RAG)] by considering the most efficient modulation format selection strategy, spectrum continuity, and conflict constraints. Through extensive simulations, we demonstrate that RAG (O-RAG) achieves close to the optimal reliability fairness with a much lower time complexity than the MILP (O-MILP) model. In particular, the path reliability-based mutation strategy in RAG (O-RAG) yields a significant performance improvement over other heuristic solutions in terms of reliability fairness, bandwidth (spectrum) consumption, and transmission delay.
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paper_title: Migration based protection for virtual infrastructure survivability for link failure

paper_content:

We propose a new migratory protection scheme that maps a virtual infrastructure to a substrate network using minimal resources to recover from a single substrate link failure. The efficiency of our solution is shown using simulation.
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paper_title: Virtual network reconfiguration in optical cloud substrates

paper_content:

This paper studies reconfiguration design for cloud-based virtual network services mapped over optical substrates. A novel scheme is proposed to improve resource efficiency and its results are analyzed versus some existing strategies.
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paper_title: Regional failure-resilient virtual infrastructure mapping in a federated computing and networking system

paper_content:

Network-wide virtualization is a promising technique that will enable future Internet to support a variety of network services and architectures over a shared optical network substrate. In network-wide virtualization, it is important to efficiently map a virtual infrastructure (VI) over a wide-area optical network and guarantee the survivability of such a VI against failures. In this paper, we study the regional failure-resilient VI mapping (RRVIM) problem, where a failure-dependent protection approach is used to enable efficient sharing of protection resources among different regional failure scenarios. We first formulate the minimum-cost RRVIM problem using mixed integer linear programming (MILP) and then propose four heuristic algorithms to solve the problem. The efficiency of the MILP and the heuristics is compared via extensive simulation experiments under various performance metrics.
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paper_title: Virtual network reconfiguration in optical substrate networks

paper_content:

This paper studies virtual network service provisioning over substrate optical networks and presents a novel reconfiguration scheme to improve efficiency. Simulation results show lower blocking and increased revenues as compared to existing strategies.
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paper_title: Review of Dynamic Impairment-Aware Routing and Wavelength Assignment Techniques in All-Optical Wavelength-Routed Networks

paper_content:

Since light-paths are the basic connections in wavelength routed networks, their effective establishment is very important. Routing and Wavelength Assignment (RWA) techniques can be divided into two categories. The first category (pure RWA) concentrates on setting up light-paths under the assumption of an ideal physical layer. However, this assumption could be suitable for opaque networks, where a signal is regenerated at each optical switch along its path. On the other hand, as an optical signal propagates along a light-path to its destination in a transparent (all-optical) network, the signal's quality degrades because there is no signal regeneration, thus increasing Bit-Error-Rate (BER) of the signal. However, users would not accept a light-path with a high BER. Even it is not acceptable if the establishment of a light-path causes the BER of other existing light-paths to become unacceptably high. Therefore, considering physical layer impairments, the quality of a light-path must be checked during the light-path setup in the second category. In this article, the operations of dynamic RWA techniques proposed in transparent networks for the second category are reviewed in detail. These techniques are called Quality of Transmission Aware (QoT-aware) RWA and are grouped in two groups: integrated QoT and RWA, and QoT after Pure RWA. Each group can be further divided into direct modelling and indirect modelling sub-groups. A comprehensive discussion is also provided to compare dynamic QoT-aware RWA techniques based on different network and physical layer parameters.
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paper_title: Routing and Spectrum Allocation in Elastic Optical Networks: A Tutorial

paper_content:

Flexgrid technology is now considered to be a promising solution for future high-speed network design. In this context, we need a tutorial that covers the key aspects of elastic optical networks. This tutorial paper starts with a brief introduction of the elastic optical network and its unique characteristics. The paper then moves to the architecture of the elastic optical network and its operation principle. To complete the discussion of network architecture, this paper focuses on the different node architectures, and compares their performance in terms of scalability and flexibility. Thereafter, this paper reviews and classifies routing and spectrum allocation (RSA) approaches including their pros and cons. Furthermore, various aspects, namely, fragmentation, modulation, quality-of-transmission, traffic grooming, survivability, energy saving, and networking cost related to RSA, are presented. Finally, the paper explores the experimental demonstrations that have tested the functionality of the elastic optical network, and follows that with the research challenges and open issues posed by flexible networks.
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paper_title: Survivable Lightpath Routing: A New Approach to the Design of WDM-Based Networks

paper_content:

Network restoration is often done at the electronic layer by rerouting traffic along a redundant path. With wavelength-division multiplexing (WDM) as the underlying physical layer, it is possible that both the primary and backup paths traverse the same physical links and would fail simultaneously in the event of a link failure. It is, therefore, critical that lightpaths are routed in such a way that a single link failure would not disconnect the network. We call such a routing survivable and develop algorithms for survivable routing of a logical topology. First, we show that the survivable routing problem is NP-complete. We then prove necessary and sufficient conditions for a routing to be survivable and use these conditions to formulate the problem as an integer linear program (ILP). Due to the excessive run-times of the ILP, we develop simple and effective relaxations for the ILP that significantly reduces the time required for finding survivable routings. We use our new formulation to route various logical topologies over a number of different physical topologies and show that this new approach offers a much greater degree of protection than alternative routing schemes such as shortest path routing and a greedy routing algorithm. Finally, we consider the special case of ring logical topologies for which we are able to find a significantly simplified formulation. We establish conditions on the physical topology for routing logical rings in a survivable manner.
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paper_title: Optimized PLI-aware virtual optical network composition

paper_content:

In this paper, a novel and optimized virtual optical network (VON) composition method, aware of the impact of physical layer impairments (PLIs), is investigated. VONs are composed using Mixed Integer Linear Programming (MILP), which can provide optimal solutions for VON composition. The quality of the composed VONs is verified by adopting an analytical assessment model of PLIs. In order to improve the performance of the PLI-aware VON composition with MILP, an optimization approach is proposed to integrate the two relatively independent phases, i.e. the VON composition and the quality verification of VON.
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paper_title: Strategies for Virtual Optical Network Allocation

paper_content:

This paper presents Integer Linear Programming (ILP) formulations to optimally allocate Virtual Optical Networks (VONs) over a transparent optical network substrate. These formulations serve the purpose of building either completely transparent VONs or opaque ones, where electrical termination capabilities are assumed at each virtual network node. In addition, a lightweight Greedy Randomized Adaptive Search (GRASP) heuristic is provided for the transparent case. The obtained results validate the accuracy of the proposed heuristic and reveal the benefits of the presented solutions against simpler shortest-path-based VON allocation strategies.
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paper_title: Virtual network planning for converged optical and data centers: ideas and challenges

paper_content:

With the development of WDM techniques and cloud computing, incorporating the optical backbone into data centers has received extensive attention. Virtual network (VN) planning has been proposed for this new networking paradigm by taking advantage of network virtualization. VN planning is essentially a united virtualization of optical and server resources in a collaborative manner. In this article, we first elaborate the advantages and problems of existing VN planning schemes through a comprehensive survey. Next, we provide a VN planning scheme. The simulation results demonstrate the effectiveness of our strategy, particularly in the context of power outage and evolving recovery. Finally, the future opportunities and challenges are also discussed.
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paper_title: Converged optical network and data center virtual infrastructure planning

paper_content:

This paper presents a detailed study of planning virtual infrastructures (VIs) over a physical infrastructure comprising integrated optical network and data center resources with the aim of enabling sharing of physical resources among several virtual operators and services. Through the planning process, the VI topology and virtual resources are identified and mapped to the physical resources. Our study assumes a practical VI demand model without any in advance global knowledge of the VI requests that are handled sequentially. Through detailed integer linear program modeling, two objective functions - one that minimizes the overall power consumption of the infrastructure and one that minimizes the wavelength utilization - are compared. Both are evaluated for the virtual wavelength path and wavelength path optical network architectures. The first objective results in power consumption savings and the two optical network architectures provide similar performances. However, the trend changes for higher load values, due to the inefficient wavelength utilization that the first objective leads to. Finally, we compare the virtual infrastructures created by the two objectives through online traffic provisioning simulations. The objective minimizing wavelength utilization results in VIs suffering higher request blocking compared to the VIs created by the objective minimizing the overall power consumption.
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paper_title: Elastic optical networking: a new dawn for the optical layer?

paper_content:

Optical networks are undergoing significant changes, fueled by the exponential growth of traffic due to multimedia services and by the increased uncertainty in predicting the sources of this traffic due to the ever changing models of content providers over the Internet. The change has already begun: simple on-off modulation of signals, which was adequate for bit rates up to 10 Gb/s, has given way to much more sophisticated modulation schemes for 100 Gb/s and beyond. The next bottleneck is the 10-year-old division of the optical spectrum into a fixed "wavelength grid," which will no longer work for 400 Gb/s and above, heralding the need for a more flexible grid. Once both transceivers and switches become flexible, a whole new elastic optical networking paradigm is born. In this article we describe the drivers, building blocks, architecture, and enabling technologies for this new paradigm, as well as early standardization efforts.
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paper_title: A Survey on OFDM-Based Elastic Core Optical Networking

paper_content:

Orthogonal frequency-division multiplexing (OFDM) is a modulation technology that has been widely adopted in many new and emerging broadband wireless and wireline communication systems. Due to its capability to transmit a high-speed data stream using multiple spectral-overlapped lower-speed subcarriers, OFDM technology offers superior advantages of high spectrum efficiency, robustness against inter-carrier and inter-symbol interference, adaptability to server channel conditions, etc. In recent years, there have been intensive studies on optical OFDM (O-OFDM) transmission technologies, and it is considered a promising technology for future ultra-high-speed optical transmission. Based on O-OFDM technology, a novel elastic optical network architecture with immense flexibility and scalability in spectrum allocation and data rate accommodation could be built to support diverse services and the rapid growth of Internet traffic in the future. In this paper, we present a comprehensive survey on OFDM-based elastic optical network technologies, including basic principles of OFDM, O-OFDM technologies, the architectures of OFDM-based elastic core optical networks, and related key enabling technologies. The main advantages and issues of OFDM-based elastic core optical networks that are under research are also discussed.
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paper_title: Elastic optical networking: a new dawn for the optical layer?

paper_content:

Optical networks are undergoing significant changes, fueled by the exponential growth of traffic due to multimedia services and by the increased uncertainty in predicting the sources of this traffic due to the ever changing models of content providers over the Internet. The change has already begun: simple on-off modulation of signals, which was adequate for bit rates up to 10 Gb/s, has given way to much more sophisticated modulation schemes for 100 Gb/s and beyond. The next bottleneck is the 10-year-old division of the optical spectrum into a fixed "wavelength grid," which will no longer work for 400 Gb/s and above, heralding the need for a more flexible grid. Once both transceivers and switches become flexible, a whole new elastic optical networking paradigm is born. In this article we describe the drivers, building blocks, architecture, and enabling technologies for this new paradigm, as well as early standardization efforts.
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paper_title: Impairment-aware optical network virtualization in single-line-rate and mixed-line-rate WDM networks

paper_content:

Optical network virtualization enables network operators to compose and operate multiple independent and application-specific virtual optical networks (VONs) sharing a common physical infrastructure. To achieve this capability, the virtualization mechanism must guarantee isolation between coexisting VONs. In order to satisfy this fundamental requirement, the VON composition mechanism must take into account the impact of physical layer impairments (PLIs). In this paper we propose a new infrastructure as a service architecture utilizing optical network virtualization. We introduce novel PLI-aware VON composition algorithms suitable for single-line-rate (SLR) and mixed-line-rate (MLR) network scenarios. In order to assess the impact of PLIs and guarantee the isolation of multiple coexisting VONs, PLI assessment models for intra- and inter-VON impairments are proposed and adopted in the VON composition process for both SLR and MLR networks. In the SLR networks, the PLI-aware VON composition mechanisms with both heuristic and optimal (MILP) mapping methods are proposed. A replanning strategy is proposed for the MILP mapping method in order to increase its efficiency. In the MLR networks, a new virtual link mapping method suitable for the MLR network scenario and two line rate distribution methods are proposed. With the proposed PLI-aware VON composition methods, multiple coexisting and cost-effective VONs with guaranteed transmission quality can be dynamically composed. We evaluate and compare the performance of the proposed VON composition methods through extensive simulation studies with various network scenarios.
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paper_title: Virtual Optical Network Embedding (VONE) Over Elastic Optical Networks

paper_content:

Based on the concept of infrastructure as a service, optical network virtualization can facilitate the sharing of physical infrastructure among different users and applications. In this paper, we design algorithms for both transparent and opaque virtual optical network embedding (VONE) over flexible-grid elastic optical networks. For transparent VONE, we first formulate an integer linear programming (ILP) model that leverages the all-or-nothing multi-commodity flow in graphs. Then, to consider the continuity and consecutiveness of substrate fiber links' (SFLs') optical spectra, we propose a layered-auxiliary-graph (LAG) approach that decomposes the physical infrastructure into several layered graphs according to the bandwidth requirement of a virtual optical network request. With LAG, we design two heuristic algorithms: one applies LAG to achieve integrated routing and spectrum assignment in link mapping (i.e., local resource capacity (LRC)-layered shortest-path routing LaSP), while the other realizes coordinated node and link mapping using LAG (i.e., layered local resource capacity(LaLRC)-LaSP). The simulation results from three different substrate topologies demonstrate that LaLRC-LaSP achieves better blocking performance than LRC-LaSP and an existing benchmark algorithm. For the opaque VONE, an ILP model is also formulated. We then design a LRC metric that considers the spectrum consecutiveness of SFLs. With this metric, a novel heuristic for opaque VONE, consecutiveness-aware LRC-K shortest-path-first fit (CaLRC-KSP-FF), is proposed. Simulation results show that compared with the existing algorithms, CaLRC-KSP-FF can reduce the request blocking probability significantly.
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paper_title: Strategies for Virtual Optical Network Allocation

paper_content:

This paper presents Integer Linear Programming (ILP) formulations to optimally allocate Virtual Optical Networks (VONs) over a transparent optical network substrate. These formulations serve the purpose of building either completely transparent VONs or opaque ones, where electrical termination capabilities are assumed at each virtual network node. In addition, a lightweight Greedy Randomized Adaptive Search (GRASP) heuristic is provided for the transparent case. The obtained results validate the accuracy of the proposed heuristic and reveal the benefits of the presented solutions against simpler shortest-path-based VON allocation strategies.
---
paper_title: Dynamic transparent virtual network embedding over elastic optical infrastructures

paper_content:

We propose a novel dynamic transparent virtual network embedding (VNE) algorithm, which considers node mapping and link mapping jointly, for network virtualization over optical orthogonal frequency-division multiplexing (O-OFDM) based elastic optical infrastructures. For each virtual optical network (VON) request, the algorithm first transfers the substrate optical network into a layered-auxiliary-graph according to the spectrum usage of each fiber link, then applies a node mapping approach that considers the local information of all substrate nodes, and accomplishes the link mapping, in a single layer of the auxiliary graph. The simulation results verify that the proposed algorithm considers the uniqueness of O-OFDM networks and outperforms two reference algorithms that directly apply the VNE schemes developed for Layer 2/3 or WDM network virtualization, by providing lower VON blocking probability. The simulations with a realistic topology also demonstrate that the average lengths of embedded substrate paths are well-controlled within the typical transmission reaches of O-OFDM signals. To the best of our knowledge, this is the first proposal that includes both link mapping and node mapping to address dynamic transparent VNE over elastic optical infrastructures.
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paper_title: Upgrade-aware virtual infrastructure mapping in software-defined elastic optical networks

paper_content:

An emerging use case in software-defined networking is to provide efficient mapping of multiple virtual infrastructures (VIs) simultaneously over the same physical substrate (PS) which can increase the resource utilization of the PS, thus improving its provider's revenue. In this paper, for the first time, we investigate a practical and yet theoretically challenging issue related to dynamic VI mapping in software-defined elastic optical networks while considering the presence of possible upgrade of the VIs and the optical layer constraints, which has not been addressed in any of the existing studies. More specifically, we investigate the following aspects: (1) Which revenue models are appropriate? (2) How to map a new VI request or to upgrade an existing VI to maximize the PS providers revenue? In particular, we study two different revenue models in terms of the incremental pricing policy and the binding pricing policy and propose a number of efficient heuristics to solve the upgrade-aware VI mapping (U-VIM) problem. We also perform comprehensive performance evaluation in different scenario, and the results show that plan-ahead is a desirable strategy when conducting VI mapping in the presence of VI upgrade.
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paper_title: Survivable virtual infrastructure mapping with dedicated protection in transport software-defined networks [Invited]

paper_content:

Efficiently mapping multiple virtual infrastructures (VIs) onto the same physical substrate with survivability is one of the fundamental challenges related to network virtualization in transport software-defined networks (T-SDNs). In this paper, we study the survivable VI mapping problem in T-SDNs with the objective of minimizing the VI request blocking probability. In particular, we address the subproblems of modulation selection and spectrum allocation in the process of provisioning optical channels to support virtual links, taking into consideration the optical layer constraints such as the transmission reach constraint and the spectral continuity constraint. We propose an auxiliary-graph-based algorithm, namely, parallel VI mapping (PAR), to offer dedicated protection against any single physical node or link failure. More specifically, the PAR algorithm can jointly optimize the assignments of mapping the primary and backup VIs by adopting the modified Suurballe algorithm to find the shortest pair of node-disjoint paths for each virtual link. Through extensive simulations, we demonstrate that the PAR algorithm can significantly reduce the VI request blocking probability and improve the traffic-carrying capacity of the networks, compared to the baseline sequential VI mapping approaches.
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paper_title: Virtual network reconfiguration in optical cloud substrates

paper_content:

This paper studies reconfiguration design for cloud-based virtual network services mapped over optical substrates. A novel scheme is proposed to improve resource efficiency and its results are analyzed versus some existing strategies.
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paper_title: Network virtualization over WDM networks

paper_content:

Network virtualization can eradicate the ossification of the Internet and stimulate innovation of new architectures and applications. Optical networks are ideal substrates for provisioning high-bandwidth virtual-network services. We investigate the problem of network virtualization over WDM networks by formulating a mixed integer linear program (MILP). Two heuristics, MaxMapping and MinMapping, are developed to solve the problem quickly but suboptimally. Numerical examples show that MinMapping consumes fewer wavelengths than MaxMapping and performs close to the optimal results of the MILP, by exploring the opportunities of traffic grooming.
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paper_title: Flexible virtual network provisioning over distance-adaptive flex-grid optical networks

paper_content:

We present a flexible virtual optical network provisioning procedure for distance-adaptive flex-grid optical networks. Simulations show ~3 times increase in effective network capacity by leveraging the combined effect of flexible node mapping and distance-adaptive modulation.
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paper_title: Virtual network embedding and reconfiguration in elastic optical networks

paper_content:

Recent innovations in Network Virtualization and Elastic Optical Networks (EONs) enable flexible deployment of optical networks as a service. However, one open challenge is how to embed Virtual Optical Network (VON) requests onto the physical substrate network to maximize the sharing of physical resources, which is the so called Virtual Network Embedding (VNE) problem. EONs are prone to the fragmentation of spectral resources during the process of routing and spectrum allocation. The fragmentation of spectral resources in the substrate fiber links may lead to the blocking of incoming virtual network requests. This degrades the utilization of the physical resources of the Infrastructure Providers and also, decreases the revenue of the Service Providers. In this paper, we propose a novel virtual network embedding algorithm called Alignment and Consecutiveness-aware Virtual Network Embedding (ACT-VNE), which takes into account the spectrum alignment and relative loss in spectrum consecutiveness when mapping virtual nodes/links onto the physical substrate nodes/links. We also propose a min-max reconfiguration scheme called Relative Consecutiveness Loss-aware and Misalignment-aware Virtual Network Reconfiguration (RCLM-VNR) that minimizes relative consecutiveness loss and maximizes alignment with adjacent links when reconfiguring the virtual network. Simulation results show that ACT-VNE and RCLM-VNR yield a lower blocking probability and a higher link utilization ratio, which leads to better utilization of the physical resources and increased revenue.
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paper_title: How to lease the internet in your spare time

paper_content:

Today's Internet Service Providers (ISPs) serve two roles: managing their network infrastructure and providing (arguably limited) services to end users. We argue that coupling these roles impedes the deployment of new protocols and architectures, and that the future Internet should support two separate entities: infrastructure providers (who manage the physical infrastructure) and service providers (who deploy network protocols and offer end-to-end services). We present a high-level design for Cabo, an architecture that enables this separation; we also describe challenges associated with realizing this architecture.
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paper_title: Virtual network reconfiguration in optical substrate networks

paper_content:

This paper studies virtual network service provisioning over substrate optical networks and presents a novel reconfiguration scheme to improve efficiency. Simulation results show lower blocking and increased revenues as compared to existing strategies.
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paper_title: Exploring Power-Efficient Provisioning for Online Virtual Network Requests

paper_content:

In the paradigm of cloud computing, multiple users can share the cloud infrastructure resources. The application or service requests from a user can be abstracted as a virtual network (VN) request and submitted to the cloud-based data centers. How to map a virtual network onto the cloud infrastructure network is a challenging issue in cloud resource provisioning. Current researches about virtual network mapping problem mainly focus on resource efficiency, which can be classified into resource efficient VN mapping or cost efficient VN mapping. However, the amount of power or energy consumed by data centers takes a large part of all of the power consumption. This may not only leads to a higher expenditure on the operation of data centers but also contribute to carbon emissions and the greenhouse effect. In this work we study the problem of power efficient virtual network mapping and propose a framework and algorithm for solving this problem. The simulation results show that our approach performs well.
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paper_title: Virtual concatenation-based elastic network embedding for inter-cloud-data-center networks

paper_content:

The elastic optical network (EON) provides fine-grained and orthogonal spectrum slots for the establishment of the elastic connection using orthogonal frequency division multiplexing (OFDM). Currently, the EON interconnection has realized the high-rate transmission among data centers (DCs). With the implementation of cloud DCs (CDCs) and EON virtualization, it becomes very essential to achieve the elastic network embedding (ENE) that facilitates the resource sharing in inter-cloud-data-center networks. The ENE operation consists of two components, the virtual-node mapping from virtual machine to CDC and the virtual-link (VL) mapping from virtual lightpath to fiber link(s). Thus an ENE request can be satisfied only when those two mapping processes have completed successfully. But during the VL mapping, some rigid constraints must be satisfied, such as the spectrum continuity, etc. This makes the ENE operation create the spectrum fragments over fiber links, which results in the denial of requests. Thus in this paper, we take the virtual concatenation (VC) into account when the VL mapping fails. The problem is formulated using the relaxed integer linear programming (ILP) model, and we also design a VC-based heuristic. Simulation results have verified the superiorities of the VC scheme on increasing the spectrum utilization and reducing the blocking rate of ENE requests.
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paper_title: Virtual network mapping for multicast services with max-min fairness of reliability

paper_content:

Network function virtualization (NFV) provides an effective way to reduce the network provider's cost by allowing multiple virtual networks (VNs) to share the underlying physical infrastructure. In the NFV environment, especially when supporting multicast services over the VNs, reliability is a critical requirement since the failure of one virtual node can cause the malfunction of multiple nodes that receive multicasting data from it. In this paper, we study for the first time to the best of our knowledge how to efficiently map VNs for multicast services over both general IP networks and orthogonal frequency division multiplexing (OFDM)-based elastic optical networks (EONs) while taking into consideration the max-min fairness in terms of reliability among distinct VNs. For general IP networks, we propose a mixed integer linear programming (MILP) model to determine the upper bound on the reliability with max-min fairness. In addition, an efficient heuristic, namely a reliability-aware genetic (RAG) algorithm, is developed to address reliable multicast VN mapping with a low computational complexity. By encoding multicast tree construction and link mapping into the process of path selection, taking into consideration the reliability with max-min fairness, and the networking reliability factors during mutation, RAG can globally optimize the reliability and fairness of all the multicast VN requests. For OFDM-based EONs, we extend the MILP (RAG) to optical-MILP [(O-MILP) optical RAG (O-RAG)] by considering the most efficient modulation format selection strategy, spectrum continuity, and conflict constraints. Through extensive simulations, we demonstrate that RAG (O-RAG) achieves close to the optimal reliability fairness with a much lower time complexity than the MILP (O-MILP) model. In particular, the path reliability-based mutation strategy in RAG (O-RAG) yields a significant performance improvement over other heuristic solutions in terms of reliability fairness, bandwidth (spectrum) consumption, and transmission delay.
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paper_title: Survivable impairment-constrained virtual optical network mapping in flexible-grid optical networks

paper_content:

In this paper, we study the problem of survivable impairment-constrained virtual optical network mapping in flexible-grid optical networks (SIC-VONM). The objective is to minimize the total cost of working and backup resources, including transponders, regenerators, and shared infrastructure, for a given set of virtual optical networks, which can survive single link failures. We first provide the problem definition of SIC-VONM, and then formulate the problem as an integer linear program (ILP). We also develop a novel heuristic algorithm, together with a baseline algorithm and a lower bound for comparison. Numerical results show that our proposed heuristic achieves results that are very close to those of the ILP for small-scale problems and that our proposed heuristic can solve large-scale problems very well.
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paper_title: Virtual network embedding in optical infrastructures

paper_content:

Optical network virtualisation has recently become a hot topic among the research community due to its potential to enable the shaping of the Infrastructure as a Service (IaaS) concept. A major challenge that arises of paramount importance when virtualising a network is the so called Virtual Network (VN) embedding problem. While this problem has been extensively treated for electrical networks, there is very little work regarding Virtual Optical Network (VONs) embedding. This paper addresses the VON embedding problem, giving an insight about the potential challenges and presenting solutions that allow to optimally solving this problem in dynamic network scenarios.
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paper_title: Fault-tolerant virtual network mapping to provide Content Connectivity in optical networks

paper_content:

We define Content Connectivity as the reachability of every content from any point of an optical network. We propose a scheme for virtual network mapping and content placement to ensure content connectivity after failures.
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paper_title: An optimized virtual network mapping using PSO in cloud computing

paper_content:

Virtualization of optical networks is key enabler of cloud computing. A main part of optical network virtualization is virtual network mapping on the physical infrastructure. One major issue in Routing and Wavelength Assignment, RWA, problem is optimized allocation of optical network resources. In this paper at first a background on Particle Swarm Optimization concept and formulation is presented. Then, an optimization scheme using PSO is proposed for virtual network mapping. Five different cost functions are formulated and a new encoding method for optical networks is proposed. The constraints for solutions of RWA problem are addressed and some heuristics are proposed to satisfy them. Proposed optimization scheme is simulated by finding the map of different virtual networks on a physical infrastructure in order to optimize five different cost functions. Results are presented and discussed for defined cost parameters.
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paper_title: Optimized PLI-aware virtual optical network composition

paper_content:

In this paper, a novel and optimized virtual optical network (VON) composition method, aware of the impact of physical layer impairments (PLIs), is investigated. VONs are composed using Mixed Integer Linear Programming (MILP), which can provide optimal solutions for VON composition. The quality of the composed VONs is verified by adopting an analytical assessment model of PLIs. In order to improve the performance of the PLI-aware VON composition with MILP, an optimization approach is proposed to integrate the two relatively independent phases, i.e. the VON composition and the quality verification of VON.
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paper_title: Virtual Optical Network Embedding (VONE) Over Elastic Optical Networks

paper_content:

Based on the concept of infrastructure as a service, optical network virtualization can facilitate the sharing of physical infrastructure among different users and applications. In this paper, we design algorithms for both transparent and opaque virtual optical network embedding (VONE) over flexible-grid elastic optical networks. For transparent VONE, we first formulate an integer linear programming (ILP) model that leverages the all-or-nothing multi-commodity flow in graphs. Then, to consider the continuity and consecutiveness of substrate fiber links' (SFLs') optical spectra, we propose a layered-auxiliary-graph (LAG) approach that decomposes the physical infrastructure into several layered graphs according to the bandwidth requirement of a virtual optical network request. With LAG, we design two heuristic algorithms: one applies LAG to achieve integrated routing and spectrum assignment in link mapping (i.e., local resource capacity (LRC)-layered shortest-path routing LaSP), while the other realizes coordinated node and link mapping using LAG (i.e., layered local resource capacity(LaLRC)-LaSP). The simulation results from three different substrate topologies demonstrate that LaLRC-LaSP achieves better blocking performance than LRC-LaSP and an existing benchmark algorithm. For the opaque VONE, an ILP model is also formulated. We then design a LRC metric that considers the spectrum consecutiveness of SFLs. With this metric, a novel heuristic for opaque VONE, consecutiveness-aware LRC-K shortest-path-first fit (CaLRC-KSP-FF), is proposed. Simulation results show that compared with the existing algorithms, CaLRC-KSP-FF can reduce the request blocking probability significantly.
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paper_title: Survivable cloud network mapping with multiple failures

paper_content:

Cloud computing services are realized through the mapping of the service layer network into the physical infrastructure. Multiple failures in the physical infrastructure could disrupt cloud network connectivity and cause cascading failures impacting cloud service customers. As the physical infrastructure has limited resources, most early research works for survivable virtual network mapping were concentrated on the single link failure scenario. In this paper, we study survivable cloud network mapping with multiple physical link failures and a special case, Shared Risk Link Group (SRLG) failure. We present the necessary and sufficient conditions to guarantee a survivable mapping with multiple physical link failures. Corresponding mixedinteger linear programming (MILP) formulations which avoid the enumeration of failure link combinations are proposed. We also provide the corresponding formulations for the SRLG case. Computation results demonstrate the viability of our approaches.
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paper_title: Performance modelling and analysis of dynamic virtual optical network composition

paper_content:

High-capacity networks based on optical technologies enable global delivery of high-performance network-based applications driven by Future Internet services. Due to the accelerated evolution of these applications, dynamic adaptability of the underlying optical infrastructure becomes crucial to support efficient data transport through the operators' networks. Optical network virtualization can be considered as a key technology for addressing this challenge. This paper presents a novel architecture enabled by optical network virtualization that adopts the concept of Infrastructure as a Service (IaaS). For the IaaS framework, three intelligent and dynamic composition mechanisms, employing Mixed Integer Linear Programming (MILP), K-Shortest Path (K-SP) and Random path routing algorithms are proposed. The performance of these algorithms in terms of the virtual optical network (VON) composition performance and the algorithm computational complexity is evaluated and compared in this study. The results show that MILP can provide optimal solutions for VON composition but it takes the longest time to execute, while the proposed Random algorithm can achieve the shortest running time.
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paper_title: Multicast service-oriented Virtual Network mapping over Elastic Optical Networks

paper_content:

Network Function Virtualization (NFV) allows multiple Virtual Networks (VNs) to share the underlying physical infrastructure via VN mapping, thus improving the utilization of physical resources. In this paper, for the first time, we study the multicast service-oriented VN mapping that can support big data applications over Elastic Optical Networks (EONs). Since the problem of minimizing the spectrum consumption in multicast service-oriented VN mapping is NP-hard, we propose an efficient heuristic algorithm, called Integrated Genetic and Simulated Annealing (IGSA) algorithm to address the problem with low computational complexity. By encoding node mapping, multicast tree construction, link mapping and spectrum requirements in the same gene and auto-adjusted evolution, and utilizing simulated annealing to find the fittest multicast requests mapping order, IGSA can perform joint optimization for all the multicast requests in a global way. Through extensive simulations, we demonstrate that IGSA outperforms the other heuristic solutions in terms of spectrum consumption, blocking probability and normalized throughput, while achieving close to minimum spectrum consumption with a much lower time complexity than MILP.
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paper_title: Planning of optical and IT resources for efficient virtual infrastructure embedding

paper_content:

This work addresses the offline problem of efficiently planning network substrates joining geographically distributed IT resource locations over high-capacity optical resources. Given an already known set of virtual infrastructure demands to be embedded over the network substrate, we present an iterative optimization heuristic that appropriately embeds all virtual infrastructure demands in order to minimize both the physical substrate IT and optical resources needed to allocate them. For this purpose, the heuristic arranges the demands in descending order, based on the amount of resources they require. Then, it processes all demands, one after another, optimally embedding each one of them on the network substrate using Integer Linear Programming (ILP) techniques. The performance of the proposed heuristic is highlighted through illustrative results.
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paper_title: Strategies for Virtual Optical Network Allocation

paper_content:

This paper presents Integer Linear Programming (ILP) formulations to optimally allocate Virtual Optical Networks (VONs) over a transparent optical network substrate. These formulations serve the purpose of building either completely transparent VONs or opaque ones, where electrical termination capabilities are assumed at each virtual network node. In addition, a lightweight Greedy Randomized Adaptive Search (GRASP) heuristic is provided for the transparent case. The obtained results validate the accuracy of the proposed heuristic and reveal the benefits of the presented solutions against simpler shortest-path-based VON allocation strategies.
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paper_title: Disaster-resilient virtual-network mapping and adaptation in optical networks

paper_content:

Today's Internet applications include grid- and cloud-computing services which can be implemented by mapping virtual networks (VNs) over physical infrastructure such as an optical network. VN mapping is a resource-allocation problem where fractions of the resources (e.g., bandwidth and processing) in the physical infrastructure (e.g., optical network and servers/data-centers) are provisioned for specific applications. Researchers have been studying the survivable VN mapping (SVNM) problem against physical-infrastructure failures (typically by deterministic failure models), because this type of failure may disconnect one or more VNs, and/or reduce their capacities. However, disasters can cause multiple link/node failures which may disconnect many VNs and dramatically increase the post-disaster vulnerability to correlated cascading failures. Hence, we investigate the disaster-resilient and post-disaster-survivable VN mapping problem using a probabilistic model to reduce the expected VN disconnections and capacity loss, while providing an adaptation to minimize VN disconnections by any postdisaster single-physical-link failure. We model the problem as an integer linear program (ILP). Numerical examples show that our approach reduces VN disconnections and the expected capacity loss after a disaster.
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paper_title: Virtual Network Embedding: A Survey

paper_content:

Network virtualization is recognized as an enabling technology for the future Internet. It aims to overcome the resistance of the current Internet to architectural change. Application of this technology relies on algorithms that can instantiate virtualized networks on a substrate infrastructure, optimizing the layout for service-relevant metrics. This class of algorithms is commonly known as "Virtual Network Embedding (VNE)" algorithms. This paper presents a survey of current research in the VNE area. Based upon a novel classification scheme for VNE algorithms a taxonomy of current approaches to the VNE problem is provided and opportunities for further research are discussed.
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paper_title: Cost-Efficient Virtual Optical Network Embedding for Manageable Inter-Data-Center Connectivity

paper_content:

Network virtualization opens the door to novel infrastructure services offering connectivity and node manageability. In this letter, we focus on the cost-efficient embedding of on-demand virtual optical network requests for interconnecting geographically distributed data centers. We present a mixed integer linear programming formulation that introduces flexibility in the virtual-physical node mapping to optimize the usage of the underlying physical resources. Illustrative results show that flexibility in the node mapping can reduce the number of add-drop ports required to serve the offered demands by 40%.
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paper_title: A survey on multi-objective evolutionary algorithms for many-objective problems

paper_content:

Multi-objective evolutionary algorithms (MOEAs) are well-suited for solving several complex multi-objective problems with two or three objectives. However, as the number of conflicting objectives increases, the performance of most MOEAs is severely deteriorated. How to improve MOEAs' performance when solving many-objective problems, i.e. problems with four or more conflicting objectives, is an important issue since a large number of this type of problems exists in science and engineering; thus, several researchers have proposed different alternatives. This paper presents a review of the use of MOEAs in many-objective problems describing the evolution of the field, the methods that were developed, as well as the main findings and open questions that need to be answered in order to continue shaping the field.
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paper_title: Virtual optical network embedding in multi-domain optical networks

paper_content:

We consider the problem of efficient virtual optical network (VON) mapping in a multi-domain optical network (VON-MD) with the objective of minimizing total network link cost for a given VON demand that is embedded over the multi-domain optical network. Topology aggregation (TA) is used to exchange intra and inter-domain information between domains, and heuristic algorithms are proposed for embedding considering different domain selection techniques and virtual link ordering techniques. We provide an integer linear programming formulation (ILP-VON-MD) to compare with our heuristic approaches. Numerical results show that our heuristic approaches are effective in reducing total network cost.
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paper_title: Effective virtual optical network embedding based on topology aggregation in multi-domain optical networks

paper_content:

We present an efficient algorithm for mapping a virtual optical network topology onto a physical multi-domain optical network with the objective of minimizing the total network link cost.
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paper_title: Virtual network mapping for multicast services with max-min fairness of reliability

paper_content:

Network function virtualization (NFV) provides an effective way to reduce the network provider's cost by allowing multiple virtual networks (VNs) to share the underlying physical infrastructure. In the NFV environment, especially when supporting multicast services over the VNs, reliability is a critical requirement since the failure of one virtual node can cause the malfunction of multiple nodes that receive multicasting data from it. In this paper, we study for the first time to the best of our knowledge how to efficiently map VNs for multicast services over both general IP networks and orthogonal frequency division multiplexing (OFDM)-based elastic optical networks (EONs) while taking into consideration the max-min fairness in terms of reliability among distinct VNs. For general IP networks, we propose a mixed integer linear programming (MILP) model to determine the upper bound on the reliability with max-min fairness. In addition, an efficient heuristic, namely a reliability-aware genetic (RAG) algorithm, is developed to address reliable multicast VN mapping with a low computational complexity. By encoding multicast tree construction and link mapping into the process of path selection, taking into consideration the reliability with max-min fairness, and the networking reliability factors during mutation, RAG can globally optimize the reliability and fairness of all the multicast VN requests. For OFDM-based EONs, we extend the MILP (RAG) to optical-MILP [(O-MILP) optical RAG (O-RAG)] by considering the most efficient modulation format selection strategy, spectrum continuity, and conflict constraints. Through extensive simulations, we demonstrate that RAG (O-RAG) achieves close to the optimal reliability fairness with a much lower time complexity than the MILP (O-MILP) model. In particular, the path reliability-based mutation strategy in RAG (O-RAG) yields a significant performance improvement over other heuristic solutions in terms of reliability fairness, bandwidth (spectrum) consumption, and transmission delay.
---
paper_title: Multicast service-oriented Virtual Network mapping over Elastic Optical Networks

paper_content:

Network Function Virtualization (NFV) allows multiple Virtual Networks (VNs) to share the underlying physical infrastructure via VN mapping, thus improving the utilization of physical resources. In this paper, for the first time, we study the multicast service-oriented VN mapping that can support big data applications over Elastic Optical Networks (EONs). Since the problem of minimizing the spectrum consumption in multicast service-oriented VN mapping is NP-hard, we propose an efficient heuristic algorithm, called Integrated Genetic and Simulated Annealing (IGSA) algorithm to address the problem with low computational complexity. By encoding node mapping, multicast tree construction, link mapping and spectrum requirements in the same gene and auto-adjusted evolution, and utilizing simulated annealing to find the fittest multicast requests mapping order, IGSA can perform joint optimization for all the multicast requests in a global way. Through extensive simulations, we demonstrate that IGSA outperforms the other heuristic solutions in terms of spectrum consumption, blocking probability and normalized throughput, while achieving close to minimum spectrum consumption with a much lower time complexity than MILP.
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paper_title: Regional failure-resilient virtual infrastructure mapping in a federated computing and networking system

paper_content:

Network-wide virtualization is a promising technique that will enable future Internet to support a variety of network services and architectures over a shared optical network substrate. In network-wide virtualization, it is important to efficiently map a virtual infrastructure (VI) over a wide-area optical network and guarantee the survivability of such a VI against failures. In this paper, we study the regional failure-resilient VI mapping (RRVIM) problem, where a failure-dependent protection approach is used to enable efficient sharing of protection resources among different regional failure scenarios. We first formulate the minimum-cost RRVIM problem using mixed integer linear programming (MILP) and then propose four heuristic algorithms to solve the problem. The efficiency of the MILP and the heuristics is compared via extensive simulation experiments under various performance metrics.
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paper_title: Migration based protection for virtual infrastructure survivability for link failure

paper_content:

We propose a new migratory protection scheme that maps a virtual infrastructure to a substrate network using minimal resources to recover from a single substrate link failure. The efficiency of our solution is shown using simulation.
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paper_title: Upgrade-aware virtual infrastructure mapping in software-defined elastic optical networks

paper_content:

An emerging use case in software-defined networking is to provide efficient mapping of multiple virtual infrastructures (VIs) simultaneously over the same physical substrate (PS) which can increase the resource utilization of the PS, thus improving its provider's revenue. In this paper, for the first time, we investigate a practical and yet theoretically challenging issue related to dynamic VI mapping in software-defined elastic optical networks while considering the presence of possible upgrade of the VIs and the optical layer constraints, which has not been addressed in any of the existing studies. More specifically, we investigate the following aspects: (1) Which revenue models are appropriate? (2) How to map a new VI request or to upgrade an existing VI to maximize the PS providers revenue? In particular, we study two different revenue models in terms of the incremental pricing policy and the binding pricing policy and propose a number of efficient heuristics to solve the upgrade-aware VI mapping (U-VIM) problem. We also perform comprehensive performance evaluation in different scenario, and the results show that plan-ahead is a desirable strategy when conducting VI mapping in the presence of VI upgrade.
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paper_title: Regional failure-resilient virtual infrastructure mapping in a federated computing and networking system

paper_content:

Network-wide virtualization is a promising technique that will enable future Internet to support a variety of network services and architectures over a shared optical network substrate. In network-wide virtualization, it is important to efficiently map a virtual infrastructure (VI) over a wide-area optical network and guarantee the survivability of such a VI against failures. In this paper, we study the regional failure-resilient VI mapping (RRVIM) problem, where a failure-dependent protection approach is used to enable efficient sharing of protection resources among different regional failure scenarios. We first formulate the minimum-cost RRVIM problem using mixed integer linear programming (MILP) and then propose four heuristic algorithms to solve the problem. The efficiency of the MILP and the heuristics is compared via extensive simulation experiments under various performance metrics.
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paper_title: Progressive recovery of virtual infrastructure services in optical cloud networks after large disasters

paper_content:

This paper studies progressive recovery in optical cloud substrates supporting virtualized infrastructure services. Several resource placement/scheduling schemes are presented to improve post-fault recovery and also evaluated against a baseline scheme.
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paper_title: Exploring Power-Efficient Provisioning for Online Virtual Network Requests

paper_content:

In the paradigm of cloud computing, multiple users can share the cloud infrastructure resources. The application or service requests from a user can be abstracted as a virtual network (VN) request and submitted to the cloud-based data centers. How to map a virtual network onto the cloud infrastructure network is a challenging issue in cloud resource provisioning. Current researches about virtual network mapping problem mainly focus on resource efficiency, which can be classified into resource efficient VN mapping or cost efficient VN mapping. However, the amount of power or energy consumed by data centers takes a large part of all of the power consumption. This may not only leads to a higher expenditure on the operation of data centers but also contribute to carbon emissions and the greenhouse effect. In this work we study the problem of power efficient virtual network mapping and propose a framework and algorithm for solving this problem. The simulation results show that our approach performs well.
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paper_title: Virtual optical network provisioning in flexible bandwidth optical networks

paper_content:

In order to address the virtual optical network (VON) provisioning problem, VON mapping approaches, which include the power-aware virtual links mapping (PVLM) approach and the power-aware virtual nodes mapping (PVNM) approach, are developed to reduce power consumption for a given set of VONs. Results show that our proposed mapping approach, PVLM, greatly reduces power consumption and saves spectrum resources compared to PVNM for different line rates and mixed line rate in flexible bandwidth optical networks.
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paper_title: Virtual network mapping for multicast services with max-min fairness of reliability

paper_content:

Network function virtualization (NFV) provides an effective way to reduce the network provider's cost by allowing multiple virtual networks (VNs) to share the underlying physical infrastructure. In the NFV environment, especially when supporting multicast services over the VNs, reliability is a critical requirement since the failure of one virtual node can cause the malfunction of multiple nodes that receive multicasting data from it. In this paper, we study for the first time to the best of our knowledge how to efficiently map VNs for multicast services over both general IP networks and orthogonal frequency division multiplexing (OFDM)-based elastic optical networks (EONs) while taking into consideration the max-min fairness in terms of reliability among distinct VNs. For general IP networks, we propose a mixed integer linear programming (MILP) model to determine the upper bound on the reliability with max-min fairness. In addition, an efficient heuristic, namely a reliability-aware genetic (RAG) algorithm, is developed to address reliable multicast VN mapping with a low computational complexity. By encoding multicast tree construction and link mapping into the process of path selection, taking into consideration the reliability with max-min fairness, and the networking reliability factors during mutation, RAG can globally optimize the reliability and fairness of all the multicast VN requests. For OFDM-based EONs, we extend the MILP (RAG) to optical-MILP [(O-MILP) optical RAG (O-RAG)] by considering the most efficient modulation format selection strategy, spectrum continuity, and conflict constraints. Through extensive simulations, we demonstrate that RAG (O-RAG) achieves close to the optimal reliability fairness with a much lower time complexity than the MILP (O-MILP) model. In particular, the path reliability-based mutation strategy in RAG (O-RAG) yields a significant performance improvement over other heuristic solutions in terms of reliability fairness, bandwidth (spectrum) consumption, and transmission delay.
---
paper_title: Multicast service-oriented Virtual Network mapping over Elastic Optical Networks

paper_content:

Network Function Virtualization (NFV) allows multiple Virtual Networks (VNs) to share the underlying physical infrastructure via VN mapping, thus improving the utilization of physical resources. In this paper, for the first time, we study the multicast service-oriented VN mapping that can support big data applications over Elastic Optical Networks (EONs). Since the problem of minimizing the spectrum consumption in multicast service-oriented VN mapping is NP-hard, we propose an efficient heuristic algorithm, called Integrated Genetic and Simulated Annealing (IGSA) algorithm to address the problem with low computational complexity. By encoding node mapping, multicast tree construction, link mapping and spectrum requirements in the same gene and auto-adjusted evolution, and utilizing simulated annealing to find the fittest multicast requests mapping order, IGSA can perform joint optimization for all the multicast requests in a global way. Through extensive simulations, we demonstrate that IGSA outperforms the other heuristic solutions in terms of spectrum consumption, blocking probability and normalized throughput, while achieving close to minimum spectrum consumption with a much lower time complexity than MILP.
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Title: A Survey on Algorithmic Aspects of Virtual Optical Network Embedding for Cloud Networks

Section 1: INTRODUCTION
Description 1: Introduce the significance of VONE in cloud computing, the challenges involved, and provide an overview of the paper’s content.

Section 2: VIRTUAL OPTICAL NETWORK EMBEDDING
Description 2: Detail the basic concepts, models, and restrictions of VONE, along with individual allocation and objective functions.

Section 3: VONE GLOBAL PERFORMANCE METRICS
Description 3: Discuss global performance metrics used for evaluating the efficiency of the VONE process.

Section 4: OPTICAL NETWORK OPTIMIZATION PROBLEMS RELATED TO VONE
Description 4: Present other relevant optical networking optimization problems and their relation to VONE.

Section 5: A CLASSIFICATION OF VONE APPROACHES
Description 5: Propose a taxonomy for VONE approaches based on physical network technology, problem approach, and optimization method.

Section 6: RESEARCH ISSUES AND CHALLENGES RELATED TO VONE
Description 6: Outline emerging research issues and challenges such as multi-objective approaches, multi-domain networks, multicast traffic, resilience, reconfiguration, and energy saving in the context of VONE.

Section 7: CONCLUSION
Description 7: Summarize the key points discussed in the survey, highlight the novel taxonomy, and suggest future research directions.