Mobile routers in a tree-based network topology with a single clusterhead in an ad hoc network establish connectivity based on each attached mobile router sending a neighbor advertisement message to an attachment mobile router via a corresponding egress interface. Any neighbor advertisement message received by a mobile router is used to identify specified network prefixes that are reachable via the source of the neighbor advertisement message. Each attached mobile router outputs to its attachment router another neighbor advertisement message that specifies the network prefix used by the mobile router, and the specified network prefixes from its attached mobile routers. The mobile router also identifies peer mobile routers having the same depth, and selectively shares limited routing information with the peer routers, enabling the mobile router to bypass the clusterhead and reach remote prefixes via the peer routers without burdening the tree.