Bi-directional Route Optimization in Mobile IP over Wireless LAN

In this paper we propose to support symmetric bidirectional route optimization in mobile IPv4 considering ingress-filtering routers. We developed subnet-based direct tunneling techniques to improve the routing efficiency for mobile IP and a binding optimization technique to reduce the handoff latency for mobile nodes. An enhanced correspondent agent was introduced to collaborate with the home agent and the foreign agent to support these techniques. Utilizing a tunneling cache, datagrams sent from a mobile node can be directly tunneled to a correspondent agent, including Binding Update messages. The proposed approach can maximize the use of a bi-directional tunnel without abandoning the transparency to existing hosts. Learning from our deployment experience, the enhanced mobile IP protocol is suitable for wireless LANs that provide broadband multimedia and location-based services. Keywords—mobile IP; route optimization; triangle routing; ingress-filtering routers; reverse tunneling