In this paper, we propose an end-to-end route optimization scheme for nested mobile networks, which we refer to as Dual Binding Update (DBU ). In general, the nested mobile networks easily suffer from a bi-directional pinball routing with hierarchically multiple mobile routers. To handle this matter, we provide a new binding update (BU) message to allow a Correspondent Node (CN) to keep an additional Care of Address (CoA). And we also allow intermediate Mobile Routers (MRs) maintain a routing table to forward packets inside the mobile network and replace a source address of the packet for reverse route optimization. We evaluate the DBU with existing schemes by analytical approaches. The results show that the DBU reduces the delay of route optimization significantly under various scenarios and also improves an average Round Trip Time (RTT) consistently for many nesting levels tested.