Research On Optimization Of Distributed Route For Mobile IP

With the fast progress of network and maturity of wireless technology, the support for the mobility of equipment is the inevitable trend of Internet development. Mobile IP, brought forward by IETF, is a solution offering the function of mobility. According to original Mobile IP protocol, each time mobile node changes its Foreign Agent, it must register to its Home Agent and correspondent node again. Due to information transmission and agreement disposal taking much time, handover causes some packets are lost for the temporary interrupt of communication.In order to reduce remote signaling traffic and lost packets, a distributed route scheme is come up. By introducing Local Agent and Redirection Agent, some management traffic can be done in local region and the lost packets are decreased owing to the buffer in Redirection Agent. Though improving the performance of Mobile IP in a certain extent, this scheme has some drawbacks. First, some out of order packets are also generated for the FIFO framework of buffer. Second, when mobile node changes its Redirection Agent, lots of packets are lost. Third, the buffer in Redirection Agent is no use when there is no handover.Aiming to overcome these shortcomings, this paper does some improvements: (1) Construct a cycle list for each mobile node and store the packets in order, so as to reduce the number of out of order packets transferred by Redirection Agent; (2) For reducing the lost packets during handover, mobile node sends buffer forwarding request information to previous Redirection Agent and forward corresponding packets to new Care of Address; (3) Through introducing the mechanism of Snoop, response to acknowledgement from mobile node in time decreases the retransmission packets.Some simulation experiments have been done under NS2. In the aspects of the size of buffer, network delay, and the speed of mobile node, the comparability on network performance is done between former scheme and the improvement scheme introduced by this paper. Results from simulation confirm the retransmission packets are reduced and the performance of Mobile IP is effectively improved using this improvement scheme.