TopoSync-SFC: SFC-aware Network-driven Synchronization of Multicast Traffic in Software-defined Environments

This paper deals with synchronized multicast reception while considering Service Function Chaining (SFC), i.e., all data packets sent towards a multicast group are first processed by the required service functions and then received by the group members at approximately the same time. This is an important requirement for several distributed applications, e.g., emergency push-to-talk services like TETRA or DMR. The presented TopoSync-SFC approach exploits recent advancements in the fields of Software-defined Networking (SDN) and Network Function Virtualization (NFV) to address synchronization directly inside the network, i.e., no dedicated support for synchronization is required by the applications. It is based on the idea of application-specific SFC-embedding multicast distribution trees that exploit paths of different length in the topology to reduce the variance in packet reception times. We present the architecture for TopoSync-SFC and an ILP-based problem formulation that respects synchronization requirements. The evaluation of a push-to-talk use-case shows that TopoSync-SFC is a significant improvement with respect to synchronized reception over approaches that do not consider synchronization.