A method, an apparatus for real-time multimedia communications using a software-defined network (SDN) are provided. The method includes receiving, in a periodic manner, a path metric associated with a first service node in the SDN and a second service node in the SDN, wherein the path metric comprises at least one of: a load status of at least one of the first service node or the second service node, or a transmission metric between the first service node and the second service node; and in response to receiving the path metric, updating a cascade network topology comprising an optimal path for transmitting multimedia data between a first edge node and a second edge node.