An information synchronization method includes sending, by a controller, a first message to a network device, where the first message carries control routing protocol (CRP) routing entry information, and is used to advertise a CRP route, and the first message includes first identification information, and after receiving the first message, storing, by a forwarding device, the CRP routing entry information into a CRP routing table of the network device as indicated by the first identification information. Hence, because a route advertised by the controller and a route advertised using a routing protocol between forwarding devices are stored in different routing tables, a related application of the route advertised using the routing protocol between the forwarding devices is not affected.