The growth of wireless networking is enabling many Internet hosts to become mobile. This article describes and compares three alternatives for providing host mobility managment in IP-based networks. We first summarize the operation and behavior of Mobile IP, on which the Internet Engineering Task Force has focused as a host mobility solution. We next describe two alternative architectures (Migrate and host identity protocol) for providing mobility management. Our qualitative comparison focuses on contrasting the different performance, security, deployment, scalability, and robustness properties of each approach.