Actionable Intelligence in the SDN Ecosystem: Optimizing Network Traffic through FRSA, demonstrates how real-time traffic analytics and SDN can be combined to perform real-time traffic engineering of large flows across a WAN infrastructure.
sFlow-RT analytics software uses a REST API to poll the nodes in the topology. In fact, the nodes stream telemetry using the widely supported, industry standard, sFlow protocol, providing real-time visibility and scaleability that would be difficult to achieve using polling - see Push vs Pull).
The load balancing application receives real-time notifications of large flows from the sFlow-RT analytics software and programs the SDN Controller (in this case OpenDaylight) to push forwarding rules to the switches to direct the large flows across a specific path. Flow Aware Real-time SDN Analytics (FRSA) provides an overview of the basic ideas behind large flow traffic engineering that inspired this use case.
While OpenDaylight is used in this example, an interesting alternative for this use case would be the ONOS SDN controller running the Segment Routing application. ONOS is specifically designed with carriers in mind and segment routing is a natural fit for the traffic engineering task described in this white paper.
Leaf and spine traffic engineering using segment routing describes a demonstration combining real-time analytics and SDN control in a data center context. The demonstration was part of the recent 2015 Open Networking Summit (ONS) conference Showcase and presented in the talk, CORD: FABRIC An Open-Source Leaf-Spine L3 Clos Fabric, by Saurav Das.