“…Light-weight Packet Marking (LPM) [19] can be used in situations where there are many malicious agents. However, LPM can only detect a suspicious node 1 Graduate School of Information Systems, The University of ElectroCommunications, Chofu, Tokyo 182-8585, Japan a) sei@is.uec.ac.jp group, which contains a suspicious node n, nodes that had sent messages to node n, and nodes that had received messages from node n. If nodes can move, the number of nodes in a suspicious node group can be very large. Therefore, the effectiveness of LPM goes away in this case.…”