A method is provided for exchanging data flows between two terminals, via a multipath link formed of a plurality of transmission channels at least one of the channels of which is a unidirectional channel. The method implements two interface modules operating in transmission mode or in reception mode, respectively. In transmission mode, an interface module separates the transmitted data flow into a plurality of secondary data flows and transits them via the plurality of transmission channels. In reception mode, it reassembles the received secondary data flows into a single data flow. The interface modules route the acknowledgement information of the data packets transiting via a unidirectional channel via the return path of a bidirectional channel.