Virtual network migration on real infrastructure:A PlanetLab case study

Network virtualization enables the deployment of novel network architectures and services on existing Internet infrastructure. In addition, virtual networks (VNs) can share the resources in the physical substrate. To enable efficient resource reallocation and network agility, VNs must sometimes migrate, i.e., change their placements on a substrate network. While VN placement, and to a lesser extent migration, has been studied in the past, little attention has been devoted to deploying and evaluating these functions over a real infrastructure. In this paper, we study the VN migration problem based on network virtualization in PlanetLab. We create a tool, PL-VNM, that orchestrates the VN migration on PlanetLab for a given new VN placement. The design and deployment of the tool reveal challenges and constraints. Some are particular to PlanetLab while others apply more generally to any virtualized infrastructure. Most significantly, we find that while in principle one can specify a migration schedule (sequence of migration steps) as an input to our tool, certain PlanetLab features make VN migration scheduling very difficult if not infeasible. Our work leads to recommendations about the features of a general virtualization environment and specific recommendations for PlanetLab that enable VN migration and migration scheduling. We believe that the recommended features make long-term experiments and application deployments on PlanetLab and other realistic virtualized infrastructures possible.