Devices, systems, methods, and techniques for multicast failover handling in a computer communication network are disclosed. The methods herein described are particularly suited to software-defined networks (SDNs), and comply with requirements for assuring delivery of network traffic to each destination from a source engaged in multicast network traffic dissemination, assured delivery of each data packet as introduced into the network by the source device and avoidance of duplicate delivery of data. The methods herein are agile and respond rapidly to changes in a network while traffic is on the network.