Implementation and evaluation of an IEEE802.11 assisted Mobile IP handover scheme

This paper describes the design and the implementation of a smooth handoff scheme using IEEE802.11 triggers. The scheme is based on the idea of Post-Registration, a Layer 3 low latency handoff scheme proposed by the IETF. In order to avoid packet loss during Layer 2 handover (i.e. while the mobile node is searching for a new access point) and during the Mobile IP registration process, packets are buffered at the old Foreign Agent. As soon as the new access point is known, a tunnel is built between the old and the new Foreign Agent and packets are forwarded through the tunnel towards the new access point. The mobile node can then perform its Mobile IP registration without losing any packets. The implementation details of the mechanism are described. Experimental results show that the handoff is smooth (i.e. zero packets are lost) and the delay induced by the buffering and the forwarding scheme is assessed.