Let the state follow its flows: An SDN-based flow handover protocol to support state migration
Manuel Peuster, Hannes Küttner, Holger Karl · 2018
Dynamically steering flows through virtualized network function instances is a key enabler for elastic, on-demand deployments of virtualized network functions. This becomes particular challenging when stateful functions are involved, necessitating state management. The problem with existing solutions is that they typically embrace state migration and flow rerouting jointly, imposing a huge set of requirements on the on-boarded VNFs, e.g., solution-specific state management interfaces. In this paper, we introduce the seamless handover protocol (SHarP). It provides an easy-to-use, loss-less, and order-preserving flow rerouting mechanism that is not fixed to a single state management approach. This allows VNF vendors to implement or use the state management solution of their choice. SHarP supports these solutions with additional information when flows are migrated. Further, we show how SHarP significantly reduces the buffer usage at a central (SDN) controller, which is a typical bottleneck in existing solutions. Our experiments show that SHarP uses a constant amount of controller buffer, irrespective of the time taken to migrate the VNF state.