For ubiquitous computing and communication, a mobile node needs to change upon movements its network- and link-layer points of attachment to the Internet. Conventionally, the network-layer protocol is unaware of the link-layer changes, so IP datagrams to and from a moving node could be lost. Considerable system performance degradation might therefore result. This paper presents a scheme to integrate the handoff procedures of the two layers in the context of Mobile IP with route optimization. Experiment results show that our scheme is promising and can reduce packet loss due to host migrations substantially.