| 摘要 |
A network system includes appliances provided in a network; a switch provided in the network; and a controller connected to the appliances and the switch. The switch contains a flow table. Entries in the flow table each specify an action to be performed on a packet matching with a matching condition. Upon receiving a packet, the switch refers to the flow table and performs the action specified by matching one of the entries which matches the received packet, on the received packet. A first appliance of the appliances performs a first packet process on a packet belonging to an existing flow, when being selected as an active appliance. When the active appliance is switched from the first appliance to a second appliance of the appliances, the controller performs a switching process after performing a shortcut process. In the shortcut process, the controller instructs the switch to set a first entry into the flow table, the first entry specifying that the first packet process is to be performed on a packet belonging to the existing flow. In the switching process, the controller instructs the switch to set a second entry into the flow table, the second entry specifying that a packet which is addressed to the active appliance and belongs to a new flow other than the existing flow is to be transferred to the second appliance.
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