Routing is based on the subnet prefix in a packet's destination IP address. Consequently, packets that are destined for a mobile node, host or router, do not reach the node when the node is not attached to the node's home link. The home link is the link where the node's home IPv6 subnet prefix exists. In order to continue communication, regardless of a node's movement, a mobile node can change its IP address each time the node moves to a new link. However, the mobile node does not maintain transport and higher-layer connections when the node changes location. Consequently, IPv6 mobility support is particularly important when recognizing that mobile computers become a significant population of the Internet in the future.
IPv6 mobility support solves this problem. IPv6 mobility enables a mobile node to move from one link to another without changing the mobile node's IP address. IPv6 mobility assigns an IP address to the mobile node within its home subnet prefix on its home link. This address is known as the node's home address.
Thus, packets that are routed to the mobile node's home address reach their destination regardless of the mobile node's current point of attachment to the Internet. The mobile node can continue to communicate with other nodes (stationary or mobile) after moving to a new link.
IPv6 mobility solves the problem of transparently routing packets to and from mobile nodes while away from home. IPv6 mobility does not solve all the problems that are related to the use of mobile computers or wireless networks. In particular, IPv6 mobility does not attempt to solve the following problems:
The ability to handle links with partial reachability, such as typical wireless networks. However, a movement detection procedure addresses some aspects.
Access control on a link that is being visited by a mobile node.