An enterprise computer system efficiently adjusts the number of middleboxes associated with the the enterprise, for example, with changes in demand, by transferring not only flows of instructions but also middlebox states associated with those flows. Loss-less transfer preventing the loss of packets and its state, and order-preserving transfer preserving packet ordering may be provided by a two-step transfer process in which packets are buffered during the transfer and are marked to be processed by a receiving middlebox before processing by that middlebox of ongoing packets for the given flow.