Hierarchical Home Agent Architecture for Mobile IP Communications

While the Mobile IP protocol does not exclude the use of multiple Home Agents (HAs), it does not impose any particular model either. Recent solutions propose that a mobile node uses multiple HAs located in different physical links in his home network. However, no architectural scheme is proposed either for unicast or multicast communications. In this paper, we propose a Hierarchical Home Agent architecture in which each Home Agent (HA) is assigned a specific topological level in its domain. The mobile node is notified about such hierarchy and chooses the closest HA on a perconnection basis. Our primary goal is to optimise both unicast and multicast routing for mobile nodes. We prove that our solution avoids redundant multicast traffic in the home domain and it is easy to implement using the current Mobile IP specification without extra cost.