Mobile IP

Routing

based on IP destination address, network prefix (e.g. 129.13.42) determines physical subnet

change of physical subnet implies change of IP address to have a topological correct address (standard IP) or needs special entries in the routing tables

Specific routes to end-systems?

change of all routing table entries to forward packets to the right destination

does not scale with the number of mobile hosts and frequent changes in the location, security problems

Changing the IP-address?

adjust the host IP address depending on the current location

almost impossible to find a mobile system, DNS updates take to long time

TCP connections break, security problems


Requirements:

Transparency

mobile end-systems keep their IP address

continuation of communication after interruption of link possible

point of connection to the fixed network can be changed

Compatibility

support of the same layer 2 protocols as IP

no changes to current end-systems and routers required
mobile end-systems can communicate with fixed systems

Security

authentication of all registration messages

Efficiency and scalability

only little additional messages to the mobile system required (connection typically via a low bandwidth radio link)

world-wide support of a large number of mobile systems in the whole Internet