A method, operated by a Software Defined Networking (SDN) controller associated with an Autonomous System (AS) with one or more peering points, each peering point with an associated router communicatively coupled to the SDN controller, the method for detecting and defending against Distributed Denial of Service (DDoS) attacks, and the method includes receiving data from the one or more peering points; detecting malicious traffic at the one or more peering points; determining a peer quality measurement for the one or more peering points; and communicating the peer quality measurement and other data associated with the malicious traffic to one or more other SDN controllers, associated with Autonomous Systems connected through the one or more peering points, to facilitate convergence of the peer quality measurement back to a nominal level.