This article puts forward a new scheme to control message redundancy efficiently in delay tolerant mobile Ad-hoc networks(MANET).The class of networks generally lacks end-to-end connectivity.In order to improve the efficiency that messages are delivered successfully,multiple message copies routing protocols are usually used,but the network load is increased due to a large number of message redundancies.In the study,by using counter method,every node adds an encounter counter based on epidemic routing scheme.The counter records the number which the node encounters other nodes with the same message copy.If the counter of a node reaches the installed threshold,the node removes the copy.Theoretical analysis gives a lower bound of threshold in delay tolerant MANET.According to the lower bound of threshold,a rational threshold is installed in real environment.With proposed scheme message copies decrease obviously and are removed completely finally.The successful delivery efficiency is still the same as epidemic routing and the redundant copies are efficiently controlled to a relatively low level.Computer simulations give the variation of message copies concerning different thresholds in fast and slow mobility scenes.
