Modeling Control Traffic in Software-Defined Networks

The southbound control protocols used in Software Defined Networks ( SDNs) allow for centralized control and management of the data plane. However, these protocols introduce additional traffic a nd d elay b etween n etwork c ontrollers and switches. Despite the well understood capabilities of SDNs, current representations of control traffic overhead consist of approximations at best. In addition to high reactivity to incoming flows, the need for resource allocation and deterministic messaging delay necessitates a thorough understanding and modeling of the amount of control traffic and its effect on latency. In this work, we capture the network overhead of various switch configurations on a testbed and extract mathematical models to predict expected overhead for arbitrary switch configurations. We demonstrate that controller-switch traffic patterns are non-negligible and can be accurately modelled to compute the bandwidth utilization and latency of controller-switch communication.