Abstract: A control plane server of a packet processing service assigns a first node group comprising exception-path nodes of the service to a network interface of a first application. Nodes of the assigned node group provide packet rewriting rules used by fast-path nodes of the service to direct requests of the application. In response to detecting that a workload migration criterion has been met, the control plane server initiates a migration workflow of the interface. During the workflow, flow state information of a packet flow is replicated at nodes of the first node group, sent from the first node group to a second node group via a fast-path node, and replicated at nodes of the second node group. Connections used for the application requests remain operational. After the migration workflow completes, nodes of the second node group provide packet rewriting rules for directing requests of the application.