Performance enhancement of smooth handoff in mobile IP by reducing packets disorder

Smooth handoff was introduced in mobile IP to overcome this problem of packet loss during handoff. However, smooth handoff causes packets sequence disruption during packet forwarding procedure, which may result in degradation of network performance in higher layer protocol. In this paper, we discuss the impact of receiving out-of-sequence packets by the mobile node on TCP and UDP applications and we propose a technique, which minimizes the arrival of out-of-sequence packets to the mobile node. This technique anticipates forwarding of packets from the current foreign agent to the new one while the mobile node initiates its handoff. To evaluate our solution, we use the unstable time period (UTP) when the packet sequence could be mis-ordered. We show that the unstable period in our solution is very low than the unstable time period in classical smooth handoff. Furthermore, we also show that our solution reduces the considerably out-of-sequence packets generated by smooth handoff.