A technique for replacing a source Virtualized Network Function Manager, VNFM, managing a source Virtualized Network Function, VNF, in a VNF based environment by a target VNFM is disclosed. A method implementation of the technique comprises the steps of triggering (S302) instantiating a target VNF, the target VNF being managed by the target VNFM and being executed in parallel to the source VNF, triggering (S304) redirecting traffic from the source VNF to the target VNF in accordance with a traffic redirection schedule, triggering (S306) terminating the source VNF when redirecting traffic from the source VNF to the target VNF is complete, and triggering (S308) terminating the source VNFM.