A software defined network, SDN, setting method, applied to a controller, comprising: sending a setting message carrying an update time to a switch after the controller detects that a connection to the switch is interrupted and receives a connection reestablishment request from the switch; and sending a first forwarding table entry to the switch, when the connection to the switch is reestablished; wherein the update time and the first forwarding table entry are configured to allow the switch to update a pre-stored second forwarding table entry in the switch, wherein the first forwarding table entry comprises a first flow table and a first metering rate-limiting table, and the second forwarding table entry comprises a second flow table and a second metering rate-limiting table, and the pre-stored second forwarding table entry is a second forwarding table entry sent by the controller to the switch before the connection between the switch and the controller is interrupted; wherein allow the switch to update a pre-stored second forwarding table entry in the switch comprises: updating the second flow table by using the first flow table and the second metering rate-limiting table by using the first metering rate-limiting table, within the update time starting from reception of the setting message; and deleting a flow table that is not updated in the second flow table and a metering rate-limiting table that is not updated in the second metering rate-limiting table, when the update time expires. sending a setting message carrying an update time to a switch after the controller detects that a connection to the switch is interrupted and receives a connection reestablishment request from the switch; and sending a first forwarding table entry to the switch, when the connection to the switch is reestablished; wherein the update time and the first forwarding table entry are configured to allow the switch to update a pre-stored second forwarding table entry in the switch, wherein the first forwarding table entry comprises a first flow table and a first metering rate-limiting table, and the second forwarding table entry comprises a second flow table and a second metering rate-limiting table, and the pre-stored second forwarding table entry is a second forwarding table entry sent by the controller to the switch before the connection between the switch and the controller is interrupted; wherein allow the switch to update a pre-stored second forwarding table entry in the switch comprises: updating the second flow table by using the first flow table and the second metering rate-limiting table by using the first metering rate-limiting table, within the update time starting from reception of the setting message; and deleting a flow table that is not updated in the second flow table and a metering rate-limiting table that is not updated in the second metering rate-limiting table, when the update time expires. updating the second flow table by using the first flow table and the second metering rate-limiting table by using the first metering rate-limiting table, within the update time starting from reception of the setting message; and deleting a flow table that is not updated in the second flow table and a metering rate-limiting table that is not updated in the second metering rate-limiting table, when the update time expires.