1. A method for determining the network connectivity between a first node and a second node connected to the first node by at least one path, the method comprising: storing a first list that identifies outgoing paths from the first node; storing a second list that identifies incoming paths to the second node; joining paths to the second node from the first node, wherein joining paths comprises accessing the first list and the second list; and using processing circuitry to determine a network connectivity indication based, at least in part, on the joined paths.