A network server having a current lower packet-interfacing layer and a current upper packet-processing layer is updated by providing an updated process having an updated packet-interfacing lower layer, an updated packet-processing upper layer packets, and a communication channel for diverting network packets from the updated lower layer to the current upper layer. First the current lower layer is replaced with the updated lower layer. Then the packets in the updated lower layer are checked to determine if they relate to transactions already under way on the current upper layer or new transactions. The current upper layer processes the packets relating to transactions already under way, and the packets relating to new transactions are processed the updated upper layer. When all the under-way transactions on the current upper layer have been completed the communication channel is closed.