Design of an SNF Scheduling Method for Bulk Data Transfers over Inter-Datacenter WANs

Increasingly bulk data transfers impose an unprecedented challenge on inter-datacenter (DC) wide area networks (WANs). To overcome this challenge, DC storage is exploited and introduced into the data-plane path so that delay-tolerant bulk data can be temporarily stored and forwarded (SnF) at a later time when network is less congested. However, the use of storage introduces additional complexity into the transfer process. In this paper, we evaluate the computational complexity of the SNF scheduling problem. Studies show that desirable performance can be attained by considering only a few alternate routes rather than dynamically routing over the entire network topology. Inspired by this finding, we propose a time-space decoupled (TSD) SNF scheduling method. By decoupling the problem into its spatial and temporal components and solving these components separately, the TSD method obtains good performance while maintaining low complexity. Simulations show that the TSD method can outperform the conventional joint method when the traffic load is medium or higher.