Ilhem Fajjari

VNE-AC: Virtual Network Embedding Algorithm Based on Ant Colony Metaheuristic

In this paper, we address a virtual network embedding problem. Indeed, our objective is to map virtual networks in the substrate network with minimum physical resources while satisfying its required QoS in terms of bandwidth, power processing and memory. In doing so, we minimize the reject rate of requests and maximize returns for the substrate network provider. Since the problem is NP-hard and to deal with its computational hardness, we propound a new scalable embedding strategy named \texttt{VNE-AC} based on the Ant Colony metaheuristic. The intensive simulations and evaluation results show that our proposal enhances the substrate providers revenue and outperforms the related strategies found in current literature.

Cloud networking: An overview of virtual network embedding strategies

This paper is an overview of virtual network embedding strategies within cloud infrastructure backbone networks. We will first of all summarise and define the main principles of cloud computing and its different supplied services. Then, we will describe the cloud infrastructure architecture, named the Totally Virtualized Cloud Infrastructure (TVCI), which makes use of virtualization in all the clouds equipment (i.e., backbone and data centers). Afterwards, we will describe, analyse, and compare the main virtual network mapping algorithms for cloud infrastructure networks found in existing literature. We will evaluate the above strategies in terms of: i) virtual network request reject rate, ii) embedding cost of virtual network request, iii) embedding revenue of virtual network request and iv) average usage rate of physical resources.

A Novel Wireless Resource Allocation Algorithm in Hybrid Data Center Networks

To this day, Cloud computing continues its explosive growth. Nevertheless, with the exceptional evolution of demands, data centers are suffering from congestion problems. To deal with these resource limitations, first, we put forward a novel Hybrid Data Center Network (HDCN) Architecture enabling high throughput wireless (IEEE 802.11 ad) and wired (IEEE 802.3) transmissions. Secondly, we propose a new resource allocation algorithm based on Graph Coloring in HDCN denoted by GC-HDCN. The main objective is to maximize the throughput of intra-HDCN communication requests over the wireless and/or wired infrastructure. The problem is formulated as minimum graph coloring which is NP-Hard. GC-HDCN makes use of i) column generation and ii) branch and price optimization schemes to resolve the assignment of wireless channels. Based on extensive simulations with Qual Net simulator considering all the layers of the protocol stack, the results obtained show that our proposal GC-HDCN outperforms the related prominent strategies in terms of i) end-to-end delay, ii) throughput and iii) spectrum spatial reuse.

An optimised dynamic resource allocation algorithm for Cloud's backbone network

Sky computing is a promising concept enabling a flexible deployment of geographical distributed applications. Whereas, it is faced with a fundamental challenge which is: “efficient resource utilisation” within Clouds infrastructure. Hence, a high flexible and intelligent resource allocation scheme is necessary to accommodate unpredictable and variable users demands. This paper tackles the fundamental challenge of efficient resource allocation within Clouds backbone network. The ultimate goal is to satisfy the Clouds user requirements while maximising Cloud providers revenue. The problem consists in embedding virtual networks within substrate infrastructure. A new dynamic adaptive virtual network resource allocation strategy named Backtracking-VNE is investigated to deal with the complexity of resource provisioning within Cloud network. The proposal coordinates virtual nodes and virtual links mapping stages to optimise resources usage. Moreover, thanks to forecasting module, Backtracking-VNE guarantees an efficient resources share between embedded virtual links with respect to their occupancy. We demonstrate through extensive simulations that contrarily to static bandwidth allocation approaches, Backtracking-VNE enhances substrate bandwidth usage whilst minimising virtual links congestion. Acceptance rate of virtual networks and Cloud providers income are also improved compared with related strategies.

A novel virtual network embedding scheme based on Gomory-Hu tree within cloud's backbone

We address the online virtual network embedding problem within the Clouds backbone to optimally map the virtual routers and links in the substrate network in order to maximize the Clouds provider revenue. Since the problem is NP-hard, we propose a novel approach, named VNE-GH, to significantly reduce the problem size using the Gomory-Hu transformation without losing useful information on the virtual network embedding problem. Starting from the Gomory-Hu compact tree structure, we formulate the virtual network embedding as an Integer Linear Program and resolve the reduced size problem using the branch- and-cut algorithm. Results obtained via extensive simulations show that VNE-GH outperforms the most prominent related work strategies in terms of i) acceptance rate of virtual network requests and ii) Cloud providers revenue.

A Novel Joint Routing and Channel Allocation Approach in Hybrid Data Center Network

The explosion of traffic demands within data centers accentuates the conventional infrastructures ossification. Unfortunately, the traditional tree based architectures struggle to resist and suffer from congestion and wiring complexity which deeply deteriorate the network performance. In aim to address the QoS degradation, we put forward a Hybrid Data Center Network (HDCN) architecture based on CISCOs Massively Data Center (MSDC) model. Specifically, it combines both the wired (Fiber and/or Gigabit Ethernet) and wireless communications based on 60 GHz band (IEEE 802.11ad). Note that few related work have dealt with the optimization of multi-hop communications in HDCN infrastructures and hence the problem is still open. In this paper, we tackle the challenge of jointly i) routing and ii) allocating wireless channels for intra data centers flows, while considering beamforming antennas. For that, we propose a new strategy named Joint Routing and Channel Allocation Algorithm (JRCA-HDCN). To do so, first the problem is formulated as a Minimum Weight Perfect Matching. Then, our resolution is based on the Blossom algorithm. JRCA-HDCN aims to maximize the throughput of intra-HDCN communication over the wireless and/or wired infrastructure. Based on extensive simulations, conducted in QualNet simulator while considering the full protocol stack, the obtained results show that our proposal outperforms the related prominent strategies in terms of i) end-to-end delay, ii) throughput and iii) spectrum spatial reuse.

A Novel Reactive Survivable Virtual Network Embedding Scheme Based on Game Theory

In this paper, we tackle the virtual network (VN) embedding problem within Cloud’s backbone network by taking into consideration the impact of physical equipment outages. Our main focus is to improve the Cloud provider’s (CPs) revenue by: 1) maximizing the acceptance rate of VNs within the Cloud’s backbone and 2) minimizing the penalties induced by service disruption due to the hardware outages. This optimization problem is non-linear multi-objective and it has been proven to be NP-hard. To cope with this complexity, we propose an advanced coordination game for VN embedding (Advanced-CG-VNE). In this mapping (i.e., embedding) game, fictitious players are playing on behalf of the CP in order to maximize the turnover. The decision makers cooperate in aim to converge to a Nash Equilibrium that we prove the existence of and the matching with a social optimum. Two variants of Advanced-CG-VNE are proposed according to the virtual links embedding approach. The first one, denoted by Advanced-CG-VNE-unsplittable, embeds each virtual link in only one substrate path. The second variant, denoted by Advanced-CG-VNE-splittable, dispatches the required bandwidth of a virtual link among a set of substrate paths. Advanced-CG-VNE does not allocate any backup to handle service interruption caused by hardware failures. Our proposal adopts preventive and reactive mechanisms to palliate substrate failures. Based on extensive simulations to gauge the effectiveness of Advanced-CG-VNE, the obtained results show that our proposal outperforms the most prominent related strategies in terms of: 1) rejection rate of VNs; 2) rate of VNs impacted by physical failures; and 3) CPs turnover.

Novel adaptive virtual network embedding algorithm for Cloud's private backbone network

In this paper, we study the adaptive virtual network embedding problem within Clouds backbone. The main idea is to take profit from the unused bandwidth but allocated to virtual networks. Consequently, the acceptance rate of new clients will be maximized. However, the congestion rate of virtual links must be minimized in order to maximize the satisfaction of end-users. To do so, first we formulate the problem as K-supplier optimization problem. Then, we propose a novel virtual network embedding strategy denoted by Adaptive-VNE. It is based on the approximation-algorithm for bottleneck problems and backtracking strategy. The proposal is validated by simulations and experimental testbed. The results obtained show that Adaptive-VNE outperforms the most prominent strategies and reaches a good performance.

Online-Batch Joint Routing and Channel Allocation for Hybrid Data Center Networks

To cope with the unprecedented traffic explosion, Internet giants are urged to rethink their data center design. Unfortunately, the conventional wired data centers struggle to support the impressive growth of both data and online services. In this regard, we resort to augmenting the wired data center network (DCN) with wireless communication (60 GHz technology). Heretofore, only few research work have dealt with the optimization of multi-hop communications in such hybrid DCN (HDCN) infrastructures. In this paper, we investigate, in HDCN, the issue of jointly: 1) routing and 2) channel allocating, in both online and batch arrival modes. First, we formulate the online joint routing and channel assignment problem as a minimum weighted perfect matching problem. We propose a new strategy named joint routing and channel allocation algorithm that makes use of the Blossom algorithm and sequentially computes the optimal routing communication paths. Second, to handle the batched arrivals of flows, we formulate the batch joint routing and channel assignment problem as an advanced multi-commodity flow model. We propose two scalable approaches: 1) a heuristic based solution, named joint routing and channel assignment heuristic and 2) an approximate solution, named scalable joint batch routing and channel allocation, based on the Lagrangian relaxation technique. Based on extensive network simulations conducted in QualNet simulator while considering the full protocol stack, the obtained results for both: 1) real Facebook’s data center and 2) uniform, traces, show that our schemes outperform the related strategies.

A novel 3D underwater WSN deployment strategy for full-coverage and connectivity in rivers

In this paper, we propose a novel 3D Underwater Wireless Sensor Network Deployment scheme for solid detection in rivers. Our objective is to minimize the number of deployed underwater sensors within a target field installation while ensuring i) the required Quality of Monitoring (QoM) (i.e., differentiated probabilistic detection) and ii) wireless network connectivity. To generate the best topology, we propose a novel deployment heuristic, named 3D-UWSN-Deploy, based on a subcube tessellation of the monitored field installation and a mixed integer linear program optimization. To gauge the effectiveness of 3D-UWSN-Deploy, we compare it with the most prominent related strategies. Simulation results show that our proposal is scalable and obtains the best performance in terms of cost deployment, quality of monitoring and connectivity.