With the ever increasing use of portable and hand held devices for voice and data transfer, there is a growing expectation to access information anytime, anywhere. Today there are different technologies providing access to voice, data, and video. These need to be converged in all Internet protocol (IP) based network. Next generation telecom networks will be having convergence of voice and data traffic and use of IP based mobility solutions. Mobile IP is a TCP/IP-based protocol that has been standardized by the IETF (Internet Engineering Task Force) for supporting mobility. Mobile IP is part of both IPv4 and IPv6 standards. Mobile IP works at network layer (layer 3), influencing the routing of packets and can easily handle mobility among different media. This chapter discusses different technical operations involved in Mobile IPv4 and Mobile IPv6 and compares them.
Mobile IP (Perkins, 1997) was originally defined for IPv4 through IETF request for comment (RFC) 2002 and finally through RFC 3344 (Perkins, 2002). The mobility support for IPv4 is an add-on, and the vast majority of IPv4 nodes do not support Mobile IP. Mobile IP for IPv4 is comprised of following four components, mobile node (MN), home agent (HA), foreign agent (FA) and correspondent node (CN) as shown in figure 1.
General scenario of data transfer in Mobile IPv4
A MN is a node, for example, a PDA, a laptop computer, or a data-ready cellular phone. A mobile node is assigned to a particular network, known as its home network. A HA is a router on the home network of the MN that maintains an association between the home IP address of the MN and its care-of address (CoA), which is the current location of the MN on a foreign or visited network. A CN is a node which is communicating with the mobile node. A FA is a router on foreign network that assists the MN in informing its current CoA to HA. IP address of MN on its home network is known as home address and it is static. The address of home agent is known as HA address. While a mobile node is attached to some foreign link away from home, it is also addressable at one or more care-of addresses. The mobile node can acquire its care-of address through conventional IPv4 mechanism. Mobile IP includes four basic capabilities to support mobility operations which are agent discovery, registration, tunneling and de-registration.