Disributing Mobility Agents Hierarchically under Frequent Location Updates

Abstract|The proliferation of wireless LAN technolo-gies and mobile terminals has prompted an increased need to support eÆcient and seamless roaming. Cur-rent mobility management protocols, such as the Mo-bile IP, as dened in RFC 2002, do not scale well into these requirements. Mobile IP employs mobility agents called home agent and foreign agent to support Internet-wide mobility. We present a distribution of the mobility agent functionalities into fully scalable, arbitrarily deep tree hierarchies of foreign agents. We show that by distributing part of the functional-ity of the home agent into the foreign network we in-crease the performance signicantly and securely. Our performance measurements show that the reduction of network latency, due to signaling locality in the hierar-chical mode, enables faster location update frequencies than in a RFC 2002-compliant non-hierarchical mode. In our solution, the Dynamics- HUT Mobile IP version 0.6-pre4, we obtained an increase in the TCP stream cuto location update frequency when using a hierarchical conguration. We also experienced sim-ilar increase when using xed speed streamed UDP traÆc with data speeds typical for some popular multi-media formats. Consequently, we claim that this kind of mobility agent architecture is suitable for scalable, fast-hando networks where multimedia streaming is used