A flooding processing method, comprising: receiving, by a controller in a Software Defined Network SDN, a data packet that is reported by a switch connected to a source host; searching, by the controller, a local MAC address table of MAC addresses of devices to determine whether a destination address of the data packet exists; acquiring, by the controller, a destination port if no destination address of the data packet exists comprising: performing, by the controller, topology stratification on switches on a network, said topology stratification comprising: acquiring, by the controller according to topology information of a switch on a network, a switch connected to a host; configuring, by the controller, the switch connected to the host as a layer 1 switch; and acquiring, by the controller, unstratified switches on the network, and configuring a switch directly connected to a layer N switch among the unstratified switches as a layer N+1 switch, wherein N indicates a layer on which the switch is located, and N is a positive integer; acquiring, by the controller according to the topology stratification, the port of the switch connected to the destination host and using the port as the destination port, wherein the destination host is another host different from the source host; and using, by the controller, the destination port as a destination address to generate a routing table, and sending the routing table to the switch connected to the source host, so that the switch connected to the source host forwards the data packet according to the routing table. receiving, by a controller in a Software Defined Network SDN, a data packet that is reported by a switch connected to a source host; searching, by the controller, a local MAC address table of MAC addresses of devices to determine whether a destination address of the data packet exists; acquiring, by the controller, a destination port if no destination address of the data packet exists comprising: performing, by the controller, topology stratification on switches on a network, said topology stratification comprising: acquiring, by the controller according to topology information of a switch on a network, a switch connected to a host; configuring, by the controller, the switch connected to the host as a layer 1 switch; and acquiring, by the controller, unstratified switches on the network, and configuring a switch directly connected to a layer N switch among the unstratified switches as a layer N+1 switch, wherein N indicates a layer on which the switch is located, and N is a positive integer; performing, by the controller, topology stratification on switches on a network, said topology stratification comprising: acquiring, by the controller according to topology information of a switch on a network, a switch connected to a host; configuring, by the controller, the switch connected to the host as a layer 1 switch; and acquiring, by the controller, unstratified switches on the network, and configuring a switch directly connected to a layer N switch among the unstratified switches as a layer N+1 switch, wherein N indicates a layer on which the switch is located, and N is a positive integer; acquiring, by the controller according to topology information of a switch on a network, a switch connected to a host; configuring, by the controller, the switch connected to the host as a layer 1 switch; and acquiring, by the controller, unstratified switches on the network, and configuring a switch directly connected to a layer N switch among the unstratified switches as a layer N+1 switch, wherein N indicates a layer on which the switch is located, and N is a positive integer; acquiring, by the controller according to the topology stratification, the port of the switch connected to the destination host and using the port as the destination port, wherein the destination host is another host different from the source host; and using, by the controller, the destination port as a destination address to generate a routing table, and sending the routing table to the switch connected to the source host, so that the switch connected to the source host forwards the data packet according to the routing table.