1. A process for routing virtual links in a frame-switching network including a plurality of source terminals and a plurality of destination terminals of frames, in which frame switches are connected to one another by physical connections, with each virtual link being defined, for a point-to-point type, by a path through the frame-switching network between a source terminal in the plurality of source terminals and a destination terminal in the plurality of destination terminals, and, for a multipoint type, by a plurality of paths through the frame-switching network between the source terminal and the plurality of destination terminals, the process, for at least one virtual link, comprises: (a) selecting, from a set of possible paths between the source terminal and the destination terminal, in case of a virtual link of the point-to-point type, or the plurality of destination terminals, in case of a virtual link of the multipoint type, a subset of paths satisfying at least one predetermined topological constraint belonging to a set of predetermined topological constraints, said set being constituted of absolute topological constraints and relative topological constraints, absolute topological constraints weighing on a routing of a virtual link independently of other virtual links in the frame-switching network, and relative topological constraints concerning virtual links with one another; (b) determining, among the subset, a path for the virtual link of the point-to-point type, or a plurality of paths for the virtual link of the multipoint type, and minimizing at least one given cost function; and (c) routing the at least one virtual link according to the path or the plurality of paths thus determined.