SDN and Optical Flow Steering for Network Function Virtualization

We propose to use software-defined optics to achieve the required flexibility, while reducing the processing load of core packet switches. It also eliminates the need to reinstall multiple packet rules each time a virtualized NF is instantiated or torn down, which can be error prone. We believe the proposal is practical as the use of optics in data centers is becoming prevalent. Assuming high traffic loads, optics can achieve much lower cost per bit than packet switching, meanwhile offering high capacity and energy efficiency. Photonic integration promises further-lower cost per bit of 100GbE and 400GbE interfaces. The dense wavelength division multiplexing (DWDM) and flexible grid technologies allow a single fiber to carry tens of simultaneous non-uniform wavelength channels for ultra-high transmission capacity and spectrum efficiency. The major drawback of optical technology is coarse traffic granularity compared with the packet solutions. However, we argue that not all scenarios require fine-grained traffic steering; aggregated traffic steered in the optical domain may achieve higher throughputs and scalability more efficiently. Moreover, thanks to the increasing agility of optical equipment, the time for establishing wavelength paths is acceptable when considering the time required to instantiate a virtualized NF.