Research On Key Technologies Of IPv4 Network Mobility

Mobile network is the hot topic in recent research with the advancement of wireless communication technologies. Popularization of mobile devices such as notebooks stimulates people's desire of accessing Internet at any time anywhere. The entire moving network deployed on vehicles like ships and trains is one of the research emphases.IETF issues Mobile IPv4 protocol, which supports terminal mobility above the IP layer. The working group MIP4 submits a draft, which gives a scheme of network mobility on co-located care-of address mode by extending Mobile IPv4 protocol, but there is no scheme of network mobility on foreign agent care-of address mode.This paper gives a new scheme to achieve network mobility on foreign agent care-of address mode by extending Mobile IPv4 protocol and adopting the denotation and message format of MIP4 draft. Compared with MIP4 draft, it costs fewer IPv4 addresses, needs fewer tunnels and less handoff time by sharing a foreign agent care-of address.To validate this scheme, this paper designs a prototype of software in Linux system with IEEE 802.11 wireless NICs in reference to the open-source software of Dynamics group. This scheme runs software on the three entities of home agent, foreign agent and mobile router to achieve network mobility. It deals with agent discovery and registration in user space, communicates with kernel by Netlink socket, amends routing policy and corresponding device information, and deals with tunneling in kernel space. Mobile router supplies routing service for mobile network nodes, which don't need to support mobile function.The test result shows that the message format and the behavior of the three entities in this scheme are compatible with Mobile IPv4 protocol and MIP4 draft, and support network mobility on foreign agent care-of address mode.