Implementation And Simulation Of Mobile IP Fast Handoff

Internet has become a necessary part of people's communication and portable devices make mobility more common. So telecommunication is no longer limited to fixed network and people are strongly desire to access to Internet fast in anywhere anytime. The diversity and development of wireless access technology make it possible but roaming between different wireless networks is a problem. So Mobile IP is put forward to solve this in network layer however it doesn't do well in handoff performance. This paper proposes a fast handoff solution based on layer 2 information and implements it on Linux platform moreover do NS-2 simulation on it.First this paper introduces the Mobile IP features, then we analysis the handoff delay in Mobile IP handoff and indicate some key points that affect it. Considering the methods put forward by Internationals about dealing the handoff by now, we choose some typical to explain and focus our attention on a fast handoff solution. This solution introduces the use of layer 2 information, builds neighbor network topology at beginning and establishs a tunnel between access router to reduce packet loss and time delay. According to the initiating time of handoff, it is expansibility and can be divided into two modes. So we call it an L3-driven fast handover.Following, thesis proposes an implementation method in detail based on Dynamics-HUT Mobile IP system. We write and modify a certain amount of modules on Mobile Node and Foreign Agent to achieve fast handoff and also use the tools on the MN that can extract information about wireless link characteristic from wireless network card to provide layer 2 trigger for handoff. The modified Dynamics-HUT Mobile IP not only supports mobile IP but also supports mobile IP fast handoff. Finally we test the packet, route and verify the protocol performance by comparing handoff delays with mobile IP handoff.In view of the protocol analysis limitation in laboratory environment, we decide to use the network simulator NS-2 to simulate it furthermore which is based on extened mobile IP modules that embedded into NS-2. First we modify this module in order to simulate fast handoff procedure and introduce mechanism to detect wireless signal strength so as to make dynamic choice among access routers. Also, we do some comparing between fast handoff and mobile IP in important parameters that can reveal network status such as throughput, packet loss and network jitter etc in the simulation process. Moreover we test the performance difference when the mobile node moves at different speed and show influence that layer 2 trigger moment impacts on fast handoff.The implemented and simulated results have indicted that layer 2 information assisted Mobile IP Fast Handoff has better performance in controlling the handoff delay and packet loss than the Mobile IP protocol.