A Study On The Fast DAD With HMIPv6

The popular of laptop computers has increased people's mobility needs in recent years. People want to access Internet while moving, and to keep the communication continuous. Being different from the fixed nodes in wired network, mobile nodes may move around during communication. Therefore, the most challenge to mobility solution is how to provide mobile nodes routing services, and how to make mobile nodes access Internet seamlessly. In order to support the mobility of mobile nodes, Mobile IP workgroup was set up in Internet Engineering Task Force. It published proponent standard of Mobile IP in Nov. 1996, which has two versions now: Mobile IPv4 based on IPv4, and Mobile IPv6 based on IPv6. However, Mobile IP aims macro-mobility more than micro-mobility. It supposes that a mobile node will stay at the visited place for a time before leaving. When handover occurs, it causes long delay and high packets loss. This is fatal to real-time applications, such as Voice over IP. Users can discover the disconnection of communication expressly. Therefore, reducing the handover delay and packet-loss rate in Mobile IP becomes the most important task. The main contribution of this dissertation is to design a Fast Duplicated Address Detection mechanism to reduce the handover delay. It introduces Fast Handover Protocol and Hierarchical Mobile IPv6 in detail first, and evaluates their advantages and disadvantages. Then it proposes Fast Duplicated Address Detection mechanism. This mechanism provides mobile nodes a simple and fast way to perform Duplicated Address Detection, and it can reduce the DAD delay, which is the largest part of the total handover delay. It is operated on mobile nodes, not influencing fixed nodes. Fast DAD can reduce handover delay and packet-loss rate in large degree. It can make Mobile IP more suitable for real-time applications. Considering the low binding update delay in HMIPv6, applying Fast DAD in HMIPv6 is discussed in this dissertation. By this method, when mobile nodes move around in one Mobility Anchor Point region, even they are far away from home agent, the handover delay can be reduced to meet the requirement of real-time application. At last, Network Simulator is used in this dissertation to simulate HMIPv6 based on Fast DAD. It makes sure that Fast DAD is feasible. Comparing the experiment data with that of HMIPv6, HMIPv6 based on Fast DAD has less handover delay and better performance.