Effects of route optimization on out-of-order packet delivery in Mobile IP networks

Packet sequence disruption caused by route optimization may result in degradation of mobile TCP/IP performance. In this paper, we propose an analytic model to investigate the impact of route optimization on out-of-order packet delivery in Mobile IP networks. When a mobile node (MN) moves to a new location, the packets sent from the corresponding node (CN) to the MN are routed indirectly through the home agent (HA). After route optimization, the subsequent packets will be sent from the CN to the MN directly. Let p be a packet traveling through the triangle path to the MN (via the HA), and q be the first packet sent via the optimized path to the MN. Packet p is sent from the CN earlier than q is. We derive the probability that packet p arrives at the MN later than packet q does, and validate the analytic model by simulation experiments. Our simulation experiments are extended to investigate how the transmission delay distributions affect the probability of out-of-order delivery. The results provide a guideline in adjusting the routing priority of binding updates to improve the end-to-end network performance.