Journal of High Speed Networks - Volume 20, issue 1

Authors: Bharti, Sourabh | Pattanaik, K.K.

Article Type: Research Article

Abstract: Current static flow scheduling techniques such as Equal Cost Multi Path (ECMP) and Valiant Load Balancing (VLB) use randomization and hash based techniques to schedule the flow in Data Center Networks (DCN). In such flow scheduling techniques, the probability of allotment of the same path for different flows at a time is high. This causes collision of flows and at times can lead to unfair link utilization. On other hand, Dynamic flow scheduling techniques such as Global first fit use a centralized mechanism to schedule flows. Global first fit can introduce the problem of unfair link utilization and also vulnerable …to a single point of failure. Effective flow scheduling is the key problem in fat-tree topology based DCNs mainly due to the bandwidth over-subscription ratio and bursty nature of traffic. In this paper, we propose a dynamic distributed flow scheduling mechanism for effective link utilization and load balancing. Moreover our proposed mechanism prevents the core switch saturation scenario by taking flow scheduling decisions at lower layers. Load measurement performed on aggregate switches for various data center traffic flow patterns reveals that the load factors across all the aggregate switches vary by at most 0.11 when dynamic distributed flow scheduling is applied without flowlet splitting. Further with flowlet splitting our dynamic distributed flow scheduling mechanism improved the load factor variation to 0.08. The load factor values signify there is considerable improvement in link utilization and the switches are fairly load balanced. The experiment scenario is simulated using Colored Petri Nets. Show more

Keywords: Load balancing, link utilization, data center networks, flowlet splitting

DOI: 10.3233/JHS-140483

Citation: Journal of High Speed Networks, vol. 20, no. 1, pp. 1-10, 2014

Authors: Abedifar, Vahid | Eshghi, Mohammad

Article Type: Research Article

Abstract: Optical networks are key enablers of the modern communication services to handle the increasing bandwidth requests. Virtualization is a feasible technology to response to the users' demands. On the other hand, the cloud computing, as a distinguished use case of the virtualized optical networks, has impacted the IT world. In virtualization of the resources, optimum mapping of the virtual optical networks on the physical infrastructure plays an important role. In this paper, a novel optimized scheme for mapping the virtual optical networks on the physical infrastructure is proposed. A new formulation for Routing and Wavelength Assignment, RWA, problem is presented. …A novel encoding method for optical networks is proposed based on categorizing the wavelengths into different groups according to data transmission rate. Then, the Genetic Algorithm, GA, and Binary Particle Swarm Optimization, BPSO, as two popular evolutionary algorithms are implemented to find the optimum map of the virtual optical networks on the physical infrastructure using the proposed encoding method. The optimization constraints and two heuristics, proposed to satisfy them, are detailed. Finally, the simulation results for a physical infrastructure and different virtual optical networks are presented. Results show that the GA outperforms the BPSO in terms of providing optimized solutions with less values of the defined cost function. But the run time required to find the optimum map of the virtual optical networks is more than the BPSO. Show more

Keywords: Evolutionary algorithms, optimization, Routing and Wavelength Assignment, RWA, virtual optical network mapping

DOI: 10.3233/JHS-140484

Citation: Journal of High Speed Networks, vol. 20, no. 1, pp. 11-27, 2014

Authors: Deng, Zuoxiang | Zhu, Yanmin | Li, Minglu

Article Type: Research Article

Abstract: Efficient routing in vehicular networks is one of the most challenging problems because of frequent network disruption and fast topological change. Some replication-based routing protocols such as epidemic routing have been proposed. However, these existing replication-based routing protocols cannot achieve high delivery ratio, low end-to-end delay and low delivery cost. In this paper, we design an efficient replication-based routing protocol called ERR for efficient routing in vehicular networks. ERR is a fully distributed protocol, and it has the following three desirable design objectives: first, ERR delivers the majority of the messages generated in time-to-live; second, ERR achieves low end-to-end delay; …third, ERR introduces as little delivery cost as possible. To achieve these design objectives, ERR adopts an adaptive strategy for the number of copies of a message in a distributed fashion. In addition, we propose two forwarding rules for a message carrier with some copies to decide whether it should forward the message when it meets a vehicle. Based on real traces of vehicles, we have conducted real trace-driven simulations. Performance results demonstrate that ERR can increase delivery ratio, decrease end-to-end delay, and decrease delivery cost, when compared with four other alternative protocols. Show more

Keywords: Vehicular networks, routing, inter-contact time, replication, forwarding rules

DOI: 10.3233/JHS-140485

Citation: Journal of High Speed Networks, vol. 20, no. 1, pp. 29-40, 2014

Authors: Liang, Zhihe | Xie, Chunli

Article Type: Research Article

Abstract: This paper consider the case when the physical graph G=Ctn (a ring of size tn) and logical graph is λKt (n). We want to minimize the number of cycles ρ(nt ,λ) in the DRC covering. For this problem, we obtain the optimal solutions when both n and t are odd.

Keywords: Wavelength division multiplexing (WDM), physical graph, logical graph, DRC covering

DOI: 10.3233/JHS-140486

Citation: Journal of High Speed Networks, vol. 20, no. 1, pp. 41-53, 2014

Authors: Sakamoto, Shinji | Kulla, Elis | Oda, Tetsuya | Ikeda, Makoto | Barolli, Leonard | Xhafa, Fatos

Article Type: Research Article

Abstract: One of the key advantages of Wireless Mesh Networks (WMNs) is their importance for providing cost-efficient broadband connectivity. There are issues for achieving the network connectivity and user coverage, which are related with the node placement problem. In this work, we compare Hill Climbing (HC), Simulated Annealing (SA) and Genetic Algorithm (GA) by simulations for node placement problem. We want to find the optimal distribution of router nodes in order to provide the best network connectivity and provide the best coverage in a set of randomly distributed clients. From the simulation results, all algorithms converge to the maximum size of …Giant Component (GC). However, according to the number of covered mesh clients, HC and SA converge faster. Show more

Keywords: Comparison study, simulation, Hill Climbing, HC, Simulated Annealing, SA, Genetic Algorithm, GA, WMN, node placement problem

DOI: 10.3233/JHS-140487

Citation: Journal of High Speed Networks, vol. 20, no. 1, pp. 55-66, 2014