An experimental investigation of SDN controller live migration in virtual data centers

Virtual data centers (VDCs) are among competitive advantages offered to businesses by cloud computing. Through VDCs, organizations can use a pool of on-demand virtual infrastructures in the form of a data center without paying the up-front costs of an actual data center. With the advent of software-defined networks (SDNs), it is now possible to provide the VDC's tenants with overlay SDNs to cover their diverse networking needs. However, live virtual machine (VM) migration, which is a technique in data centers to address issues such as load balancing, imminent server failure, and host maintenance can require parts of or an entire overlay SDN to be migrated to a different host. This introduces challenges which need to be addressed. Otherwise, the services running on the overlay SDNs will get interrupted which may lead to a low quality of end user experience (QoE) as well as a violation of service level agreements (SLAs) by the cloud service providers. Investigating SDN controller live migration in a virtual data center needs a testbed which brings into account cloud, SDN, VM migration, and overlay networks, to name a few. This paper introduces such a testbed and investigates SDN controller live migration in a virtual data center. It identifies container size, traffic volume, traffic pattern and transport layer protocol throughput as contributing factors of a successful SDN controller live migration. It then clarifies how these factors may affect a live migration process in terms of migration time and down time through conducting experiments on a state-of-the-art cloud data center testbed.