Openflow as emerged as the pioneering protocol relating to Software Defined Networking and the hopes to transform networking as we know it. One of the biggest complaints with Openflow for real deployment is the lack of scale.
Recently, Broadcom an ASIC manufacturer published a new API scheme that shows the implementation of Multiple table pipe-lining which started in Openflow 1.1 but mostly talked about with 1.3.1. This pipe-lining approach allows switch vendors to exploit the many tables already in the current hardware. This API is significant as its implementation could turn the corner for real Openflow deployments in the year or so.
The other side to the scaling challenge is that Broadcom and other chip vendors are developing ASICs with much larger ACL tables closer to 100K to provide more flexibility in designing Openflow networks.