For routing in a communications network, alternate paths to a destination are aggregated into a single composite route, prior to onward propagation of the route. Ideally, aggregation is performed at each point of route convergence in the network. Consequently, failure in only one of the paths does not then require that the composite route be withdrawn, and thus visibility of and reaction to the fault is restricted to parts of the network directly affected. The method is particularly applicable to border gateway protocols employed between Autonomous Systems as in, for example, the Internet.