Is It for You? So, should you rush out and get Mobile IP? First ask yourself how often you connect into another company's network. When were you last able to jack into a network, other than by using a phone connection, in your hotel room or at the airport? As desirable as this might be, it is not yet an option. Mobile network connections are not part of mainstream computing today, but as the demand for connections to the Internet increases, that will likely change.

A more immediate need for many companies is to allow their workers to connect to the corporate network from other locations--such as a different building on a campus or at a remote office . Mobile IP makes this possible. Meanwhile, Mobile IP is increasingly being used in specialized applications, particularly vertical market applications involving wireless LANs, such as car rental depots, freight handling and supermarket inventory.

Mobile IP also is being designed into the infrastructure of some new wireless WANs. Cellular Digital Packet Data (CDPD), the dominant wireless WAN that routes IP, provides its own IP mobility service. Like Mobile IP, it forwards packets from a home network to a foreign network.

You should consider Mobile IP if you have computers that need to stay connected with IP applications running as they roam from one subnet to another.

Using Mobile IP Mobile IP is easy to use, but, unfortunately, few commercial implementations of it exist. FTP Software, the only company currently offering Mobile IP, combines the home agent and foreign agent into one Windows application as part of its Secure Client 3.0. A workstation is required to house the home agent, and one is needed for the foreign agent at every network the mobile node will visit.

Using a different approach, Telxon Corp. has integrated home and foreign agents directly into Aironet Wireless LAN access points. To configure Mobile IP, you specify the home agent and security parameters at the mobile node and a list of authorized mobile nodes at the home agent. You also can specify mobile node authentication information at each foreign agent.

Once demand for Mobile IP increases, vendors can build home and foreign agents directly into routers, though no such products have been announced. This would simplify Mobile IP's use, since all you would need is the mobile node. Keep in mind that while the Mobile IP standard has been completed, revisions are under way, and work on related standards is continuing. Until all this work is done, you may run into compatibility problems among products.