A path discovery process is provided for discovering a lowest cost combination of a plurality of paths from the source node to the destination node via links between pairs of nodes along the paths. A path discovery messages from a source node is forwarded through the network. Prior to forwarding the path discovery message a node tests one or more conditions for disabling the forwarding. Upon receiving an instance of the path discovery message, this may include testing whether no other instance of the path discovery message has both smaller cost and a previous path that contains only nodes that occur also in the path of the received instance. Furthermore, this may include testing whether a destination of the path discovery message was also a node to which a preceding node along the path has a further link, and a cost of the path from the preceding node to the next node via said further link is not larger than the cost of the path from the preceding node to the next node. Furthermore, this may include testing whether the node has a further link to the destination node and the cost associated with the link to the next node is not less than the cost associated with the further link to the destination node.