Early-Warning-Time-Based Virtual Network Live Evacuation Against Disaster Threats

Network virtualization enables cloud service providers sharing various substrate resources and serving end users with heterogeneous virtual network (VN) applications. As more and more Internet applications migrate to the cloud, the survivability of VNs, particularly for disaster survivability, has become a crucial issue. In this article, we study the VN survivability problem and propose an early-warning-time-based VN live evacuation (EVLE) scheme to combat against disaster threats. Aiming at an upcoming disaster destruction, EVLE tries to evacuate as many VNs as possible from the disaster risk zone (DRZ) before the given deadline, while sustaining their online services. The evacuation mainly includes two processes, viz., VN reconfiguration and virtual machine (VM) live migration. For a threatened VN, EVLE first remaps it at the outside of the DRZ with minimal resource cost, then exploits the postcopy technique to migrate the impacted VM to the corresponding reconfigured virtual node. During the VM migration process, the operations of basic bandwidth deployment and bandwidth upgradation are implemented, so as to encourage parallel migrations and maximize the resource utilization within the period of early-warning time. In our simulations, the EVLE and a baseline scheme, as well as a counterpart named as best-effort VN live evacuation (BVLE), are tested with different disaster scenarios. Numerical results illustrate that the EVLE, even if with a longer average evacuation time, can outperform the baseline scheme and BVLE in terms of the evacuation completion ratio under different early-warning times, and particularly can achieve distinct dominance under small early-warning times.