This work presents a simple mobility scheme for IP-based networks, termed the "anchor chain" scheme. The scheme combines pointer forwarding and caching methods. Every mobile host (MH) is associated with a chain of anchors that connects it to its home agent. Each anchor defines the location of the MH at a certain degree of accuracy. The accuracy is increased along the chain until the attachment point of the MH is reached. We develop distributed procedures for updating the anchor chain (binding operation) with MH movements and for delivering messages to a MH (delivery operation). In terms of worst-case performance, the total cost of the binding operations is O(MovelogMove), where Move is the total geographic distance that the MH has traveled since its activation. The total length of the MH's pointer path is linear with the distance between the MH and its home network, and the delivery cost is near-optimal. In addition, the anchor chain of a MH is determined dynamically with no need for preliminary definitions of static anchors or regions. Our simulation results show that the anchor chain scheme also yields lower average overheads for both the binding and the delivery operations than other methods that are described in the literature, including the current home approach. We believe that the proposed scheme is scalable, fairly easy to implement and therefore attractive for supporting MH.
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