A method which includes: obtaining, by a controller, at least two transmission paths between a first edge node and a second edge node; obtaining, by the controller according to bandwidths of the at least two transmission paths, a maximum bandwidth provided by a cluster system, where a bandwidth of each of the transmission paths is equal to a smallest bandwidth in bandwidths of all transmission links in the transmission path, and the maximum bandwidth is less than a sum of bandwidths of at least two transmission links connected to the first edge node; and announcing, by the controller, the maximum bandwidth to a node outside the cluster system by using the first edge node and/or the second edge node. According to the method, accuracy of a maximum bandwidth that is announced by a cluster system to a node outside the cluster system can be improved.