  Network hypervisors provide the network virtualization layer for Software
Defined Networking (SDN). They enable virtual network (VN) tenants to bring
their SDN controllers to program their logical networks individually according
to their demands. In order to make use of the high flexibility of virtual SDN
networks and to provide high performance, the deployment of the virtualization
layer needs to adapt to changing VN demands. This paper initializes the study
of the optimization of dynamic SDN network virtualization layers. Based on the
definition of reconfiguration events, we formalized mixed integer programs to
analyze the multi-objective problem of adapting virtualization layers. Our
initial simulation results demonstrate Pareto frontiers of conflicting
objectives, namely control plane latency and hypervisor and control path
reconfigurations.
