RBU+: Recursive Binding Update for End-to-End Route Optimization in Nested Mobile Networks

In this paper, we propose an end-to-end route optimization scheme for nested mobile networks, which we refer to as Recursive Binding Update plus (RBU+). A nested mobile network is a hierarchical form of mobile networks. Nested mobile networks suffer from a pinball routing problem with hierarchical mobile routers. This problem becomes more serious in the case of macro mobility, as the routing distance becomes longer. To solve the pinball routing problem of nested mobile networks, in this paper we propose the Recursive Binding Update (RBU) and three distinct solutions for the end-to-end routing in mobile networks using the method of obtaining the route from the Top Level Mobile Router (TLMR) to the destination Mobile Network Node (MNN). The solutions for end-to-end routing include source routing, Table Driven Forwarding (TDF), and Route Request Broadcast (RRB). From the results of the simulations, it was shown that RBU+RRB presents the best performances among the different solutions. When combined with an end-toend routing capability, RBU+ provides optimal routing in nested mobile networks. RBU+ reduces the pinball routing cost, and this reduction becomes more significant as the degree of nesting becomes higher and the distance between the home agents of the mobile router and its parent/child mobile routers becomes longer. When combined with an appropriate reverse route optimization scheme, the routing costs are independent of the degree of nesting and the distance between the Home Agents (HAs).