In an embodiment, a method of identifying critical nodes in a wireless network from a network topology graph for the network, the wireless network comprising a plurality of nodes and a plurality of links between the nodes, and the network topology graph for the network indicating the plurality of links between the nodes comprises: selecting each node in turn as a candidate node, and for each candidate node: generating a network topology graph for a sub-network comprising all of the nodes of the wireless network except the candidate node; determining from the network topology graph for the sub-network if the sub-network is fully reachable; and generating an indication that the candidate node is a critical node if the sub-network is not fully reachable.