Protocols to support autonomy and control for NFV in software defined networks

Abstract

The use of Network Function Virtualization to run network services in software enables Software Defined Networks to create a largely software-based network. We envision a dynamic and flexible network that can support a smarter data plane than just simple switches that forward packets. This network architecture needs to support complex stateful routing of flows where processing by network functions (NFs) can dynamically modify the path taken by flows, without unduly burdening or depending on the centralized SDN controller. To this end, we specify a protocol across the different components of an SDN-NFV environment to support the creation of NFs required by a service graph specification, using an orchestrator speaking to an NF Manager running on each host. We take advantage of, and extend, the concept of the SDN controller-to-node protocol (OpenFlow being the most popular) and tagging flows to support complex stateful routing. Output generated by NFs processing packets may be returned to the NF Manager to influence dynamic route changes based on a priori rules defined through a service graph specification provided by network administrators. We envisage the SDN controller setting up these rules based on the output from NFs, the flow specification as well as global tags. By not treating tags as an independent component for routing, we show that we can dramatically reduce the number of tags required across the entire network. Further, by providing the right autonomy in decision making at the NF Manager and the individual NFs in our hierarchical control framework, we significantly reduce the load on the SDN controller.