There is a growing range of IP-based data and voice applications using mobile devices (e.g. 3rd , 4th generation mobile phones and PDAs) and new access technologies (e.g. Bluetooth, 802.11, GPRS, ADSL). This growth is driving a desire to support mobility at the IP level � in other words, allowing an IP host to keep on communicating with other hosts while roaming between different IP subnetworks. Mobile IPv6 allows hosts to move their physical and topological attachment points around an IPv6 network while retaining connectivity through a single, well-known Home Address. Although Mobile IPv6 has been the subject of simulation studies, the real-world dynamic behavior of Mobile IPv6 is only gradually being experimentally characterised and analysed. This thesis reviews the use of Mobile IPv6 to support mobility between independent 802.11b-attached IPv6 subnets, and experimentally measures and critically evaluates how long an end to end IP path is disrupted when a Mobile IPv6 node shifts from one subnetwork to another (handoff time). The thesis describes the development of an experimental testbed suitable for gathering real-world Mobile IPv6 handoff data using publicly available, standards compliant implementations of Mobile IPv6. (An open-source Mobile IPv6 stack (the KAME release under FreeBSD) was deployed). The component of handoff time due to 802.11b link layer handoff is measured separately to assess its impact on the overall Mobile IPv6 handoff time. Using Mobile IPv6 handoff results, the likely performance impact of Mobile IPv6 handoff on a common webcam application and a bulk TCP data transfer is also evaluated. The impact of handoff on these applications clearly shows that a default Mobile IPv6 environment would be highly disruptive to real-time and interactive applications during handoff events, even if the underlying link-layer handoff was instantaneous.