Mobile IPv6 extensions to support nested mobile networks

Unlike host mobility support, network mobility is concerned with situations where an entire network changes its point of attachment to the Internet. Furthermore, we should consider the situation of several mobile networks recursively attached together. The goal of network mobility support is to provide continuous and optimal Internet access to all nodes located in the mobile network. In this paper we present a solution to support nested network mobility by extending MIPv6. Note that the IETF MIPv6 protocol is for mobile nodes and not for mobile networks according to D. B. Johnson et al. (2002). The main idea is to register a prefix binding in HA and CN with a chain of intermediate mobile router's (MRs) care-of-addresses (CoAs). To the main idea, we introduce new option; the nested care-of-address option (NCO) is used to carry a sequence of MR's CoAs in the header. The router alert option (RAO) is used to indicate that NCO is set. When RAO is set, it is not necessary to encapsulate an outgoing packet. The HA and CN can use the addresses in its binding cache to construct a Type 2 Routing Header to send packets into the mobile network. This extension allows our scheme to give an optimal routing path, avoid the tunnel-in-tunnel problem, save the bandwidth resource and reduce the computation overhead in the home network.