Inter-datacenter Wide Area Networks Research Articles

Performance study of an SnF scheduling method for bulk data transfers over inter-datacenter WANs

The rise of emerging services has brought a rapid growth in bulk data transfers across inter-datacenter (DC) wide area networks (WANs). To accommodate the demands of such services, DC storage is introduced into the data-plane path so that delay-tolerant bulk data can be temporarily stored and forwarded (SnF) when network is less busy. However, the use of storage transforms a conventional routing problem into a scheduling problem, where spatial routing and temporal scheduling must be jointly performed. Moreover, the complexity of the problem increases exponentially with the scale of the network as well as the number of storage sites. While prior SnF scheduling methods are effective for small networks or for static traffic, they are either too complex or insufficient for large networks with dynamic traffic. In this paper, we study the performance-complexity tradeoff in SnF scheduling. Studies show that desirable performance can be attained by considering a few alternate routes rather than dynamically routing over the entire network topology. Thus, our proposed SnF scheduling method aims to decouple the problem into its spatial and temporal components, and then solve these components separately. The proposed method hence has low complexity while still achieving high performance. Simulations demonstrate that when the traffic load is medium or higher, the conventional joint method may suffer from the detour issue. In this case, the proposed method has the potential to outperform the conventional joint method even with only three alternate routes considered in SnF scheduling.

Delay-Sensitive Multicast in Inter-Datacenter WAN Using Compressive Latency Monitoring

Multicast routing in inter-datacenter wide area networks is to compute a multicast tree from a source datacenter to multiple destination datacenters. Software-defined networking enables optimal delay-sensitive routing for multicast sessions in inter-datacenter WANs. Delay-sensitive routing requires the controller to obtain the up-to-date latency of every link. However, the communication overhead and time for collecting the latency information of all links can be prohibitively high for the controller to perform real-time scheduling in a WAN. Inspired by the sparsity of link load information in WANs, we propose compressive latency monitoring, a real-time method for collecting a near-accurate latency information of all links. The controller only needs to collect the latency information of a small subset of significant links and then estimates the latency information of insignificant links. We use real-world network topologies to simulate multicast routing both under the compressive latency monitoring and global latency monitoring. Simulation results show that the compressive latency monitoring can achieve nearly good network throughput performance as the global monitoring with much less communication overhead and in a more timely fashion.

A Completion Time-Based Flow Scheduling for Inter-Data Center Traffic Optimization

With the rise of cloud computing service, traffic in inter-data center wide area networks (inter-DC WANs) has been growing rapidly. Inter-data center traffic contains multitudinous data transfers that require to be accomplished within certain time periods or deadlines. The different completion time of the transfer tasks has distinct impacts on the performance of the whole system. However, very little work takes the completion time into account while guarantees the hard deadlines. Besides, most previous works arrange transfers exclusively, which does not take fairness into account. In this paper, we introduce a completion time-based model, which takes multiple deadlines and their impacts into consideration to profile a more accurate characterization of the data transfers. We propose a novel mechanism to achieve the goals of both maximizing utility and fairness. We also develop an inter-DC WAN emulation tool which enables a single commodity server to emulate arbitrary topology and dynamic configuration on the WAN links. Our evaluation demonstrates that our algorithm gains 110%–250% utility than current deadline focus mechanisms, while achieves 12% higher throughput. Fairness is improved over four times at best by adjusting the fairness coefficient.

Guaranteeing Deadlines for Inter-Data Center Transfers

Inter-data center wide area networks (inter-DC WANs) carry a significant amount of data transfers that require to be completed within certain time periods, or deadlines. However, very little work has been done to guarantee such deadlines. The crux is that the current inter-DC WAN lacks an interface for users to specify their transfer deadlines and a mechanism for provider to ensure the completion while maintaining high WAN utilization. In this paper, we address the problem by introducing a deadline-based network abstraction (DNA) for inter-DC WANs. DNA allows users to explicitly specify the amount of data to be delivered and the deadline by which it has to be completed. The malleability of DNA provides flexibility in resource allocation. Based on this, we develop a system called Amoeba that implements DNA. Our simulations and test bed experiments show that Amoeba , by harnessing DNA’s malleability, accommodates 15% more user requests with deadlines, while achieving 60% higher WAN utilization than prior solutions.