The Mobile IP protocol is designed to allow network nodes to maintain their IP connectivity with remote nodes while moving from one point of attachment to another. The Mobile IP protocol is mostly designed for wireless devices, although it can be used with any wired technology.
The Mobile IPv6 protocol has important design changes compared to Mobile IPv4:
Foreign agent— Mobile IPv6 has no foreign agent, because each mobile IPv6 node can handle the mobility. However, the home agent is still mandatory in IPv6.
Internet nodes— Any compliant IPv6 node has mobility support built in. This is not the case in IPv4, because the Mobile IPv4 support is an addition to the IPv4 protocol.
Registration— UDP on port 434, used in IPv4 to ...