Research And Implementation Of Delay-Based Route Optimization Mechanism In Mobile IPv6

Due to rapid growing up of the Internet and success of the mobile wireless systems, lots of applications have been developed on wireless personal communication systems such as SMS, e-mail, MMS and on-line games, etc. Therefore, a protocol with mobility-enabling for the global Internet, Mobile IP is proposed. It provides a scalable indirection mechanism allowing the mobile nodes to maintain network layer connectivity across mobility. One of the most well known "problem" with Mobile IP is the triangular routing problem. It usually leads to additional delays, lies in that each packet destined to the mobile node must be routed through the home agent along an indirect path. Hence, Route Optimization is proposed to solve this issue.Based on the thoroughly study of Route Optimization, a delay-based route optimization mechanism is presented. RRP is utilized to guarantee the security in the proposed mechanism, but Timestamp is added to both HoT and CoT messages to measure the propagation delays of dirct path and indirect path respectively. The path with lower delay is chosed. If the direct path is chosed, inorder to avoid disorder packets, the packets transmitted in the direct path aren't forwarded to mobile node directly. Mobile node's access router buffers these packets until it receives LAST message, which implies all the packets in the indirect path have been forwarded to mobile node. If mobile node's access router didn't receive the LAST message during the delay skew of indirect path and direct path, it forwards the bufferd packets to mobile node at once. This mechanism not only decides which path is chosed but also improves the performance of route optimization.In this thesis, some technologies about mobile IPv6 and route optimization are introduced first. Then a delay-based route optimization mechanism for mobile IPv6 is proposed. By installing and modifying a NS attachment packet, mobiwan, Return Routability Procedure, measuring the propagation delay and buffering the packet from direct path before all the indirect data transmitted to mobile node is accomplished. At last by analyzing the simulation result and experiment data, the feasibility of the proposed mechanism is validated.