The present disclosure relates to resource reservation methods. One example method includes receiving, by a controller, a resource reservation request that is of a communication session and that is sent by a sending device, where the resource reservation request carries resource requirement information, obtaining, by the controller based on the resource reservation request, identification information of a network device through which data transmission of the communication session to be performed between the sending device and a receiving device passes, and a resource index of the network device, sending, by the controller, the resource requirement information and the resource index to the network device based on the identification information, where the resource requirement information and the resource index are used to instruct the network device to configure a resource for the communication session, and sending, by the controller, the identification information and the resource index to the sending device.