CoVisor: A Compositional Hypervisor for Software Defined Networks

CoVisor, a new network hypervisor …: assembly of multiple controllers: the hypervisor intercepts and processes industry-standard OpenFlow messages; abstracts concrete topologies
CoVisor, a hypervisor that exploits efficient new algorithms to compile and update policies from upstream controllers, each of which has its own view of the network topology: primary challenge surrounding the creation of such a fully featured hypervisor is efficiency; efficient algorithms for composing controller policies, for compiling virtual networks into concrete OpenFlow rules, and for efficiently processing controller rule updates.
CoVisor algorithm, key insight: rule priorities form a convenient algebra to calculate priorities for new rules, obviating the need to recompile from scratch for every rule update

2 overview

the network administrator configures CoVisor to compose controllers with a simple language of commands

take member policies (OpenFlow commands issued from a controller to CoVisor) as input

produce a single composed policy

action (a) default
T1 + T2 in parallel
T1 >> T2 in sequence