The TCP/IP Guide  9  TCP/IP Lower-Layer (Interface, Internet and Transport) Protocols (OSI Layers 2, 3 and 4)       9  TCP/IP Internet Layer (OSI Network Layer) Protocols            9  Internet Protocol (IP/IPv4, IPng/IPv6) and IP-Related Protocols (IP NAT, IPSec, Mobile IP)                 9  Internet Protocol Mobility Support (Mobile IP)

Internet Protocol Mobility Support (Mobile IP) 1 2 3 4 Mobile IP Concepts and General Operation

Limitations of Mobile IP

It’s important to realize that Mobile IP has certain limitations in its usefulness in a wireless environment. It was designed to handle mobility of devices, but only relatively infrequent mobility. This is due to the work involved with each change. This overhead isn't a big deal when you move a computer once a week, a day or even an hour. It can be an issue for “real-time” mobility such as roaming in a wireless network, where hand-off functions operating at the data link layer may be more suitable. Mobile IP was designed under the specific assumption that the attachment point would not change more than once per second.

I should also point out that Mobile IP is intended to be used with devices that maintain a static IP configuration. Since the device needs to be able to always know the identity of its home network and normal IP address, it is much more difficult to use it with a device that obtains an IP address dynamically, using something like DHCP.

Internet Protocol Mobility Support (Mobile IP) 1 2 3 4 Mobile IP Concepts and General Operation