Aspects of the disclosure relate to mechanisms for interworking between legacy and next generation radio access technologies (RATs) in a communication network. In some examples, a handover from a next generation access network to a legacy access network may be performed via a next generation core network and a legacy core network. A handover request received at a next generation core network serving node may include an identifier of a target cell within the legacy access network. The next generation core network serving node may identify a legacy core network serving node to which the handover may be forwarded based on the target cell identifier. Packet data units may then be routed over the legacy access network and the next generation core network by mapping data flows in the next generation core network to packet data connections in the legacy access network.