MobileNAT: A New Technique for Mobility Across Heterogeneous Address Spaces

Abstract

We propose a new network layer mobility architecture called MOBILENAT to efficiently support micro and macro-mobility in and across heterogeneous address spaces common in emerging public networks. The key ideas in this architecture are as follows: (1) Use of two IP addresses - an invariant virtual IP address for host identification at the application layer and an actual routable address at the network layer that changes due to mobility. Since physical address has routing significance only within a domain, it can be a private address and therefore, does not deplete the public IP address resource. (2) New DHCP enhancements to distribute the two addresses. (3) A new signaling element called Mobility Manager (MM) that uses Middlebox Communication (MIDCOM) framework to signal the changes in packet processing rules to the Network Address Translators (NATs) in the event of node mobility. Our proposal does not require any modifications to the access networks and can seamlessly co-exist with the existing Mobile IP mechanisms and therefore, can be used to provide seamless mobility across heterogeneous wireline and wireless networks. We report implementation details of a subset of our ideas in a testbed with Windows XP clients and Linux based NATs.