I’ve stated repeatedly in this column that the only real business case for IPv6 is its address space. But taking that as a given, there are a few other attractive characteristics of IPv6; arguably the most frequently cited of these is mobility. The elimination of foreign agent requirements, route optimization through binding updates with the correspondent node, session persistence, and the promise of fast layer 3 handovers all make mobile IPv6 (MIPv6) more compelling than MIPv4.
When we think of mobility we usually think of single device mobility. But the truly interesting aspect, in my opinion, is network mobility (NEMO). In NEMO it is a router that carries and manages the mobility functions. The subnet or subnets attached to the router, and the devices attached to those subnets, do not even know they are mobile.
The stock example of NEMO is a mobile router on an airplane or train or other public transportation. The passengers all attach via WiFi or similar low-range wireless technology, or perhaps have the option of plugging in to an Ethernet port at their seat. The plane or train becomes a mobile subnet managed by a single on-board mobile router using a long-range broadband wireless technology.
This becomes even more application-flexible because the mobile router itself can be attached to another mobile router: You could have a hierarchy of “nested” mobile routers. This has tremendous promise of new kinds of solutions for public transport, military, and interoperable first-responder communications networks.
One of the early applications of NEMO could be for Personal Area Networks (PANs), which have been talked about for many years: You have a number of IPv6-enabled devices on and around your person such as a laptop, PDA, NTP-enabled wristwatch, entertainment system, and VoIP phone attaching to a mobile router via a number of short-range wireless technologies (Bluetooth, 802.11, ZigBee).
Rather than think of a 6” x 6” LinkSys or D-Link router awkwardly clipped to your belt, think of router functionality in the one device that is likely to always be in your pocket or pocketbook: Your mobile phone. That device has already seen the incorporation of schedulers and address books, music and photo albums, credit cards, and of course cameras (ten years ago if someone said there would be a camera in most mobile phones, you might have thought it impractical because the film canister would make it too bulky). The common factor driving the incorporation of these diverse functions in the mobile phone is that the phone is almost always on our person, so these functions are also always on our person, handily accessible when needed.
Adding a MIPv6 router to mobile handsets is technologically feasible and likely to be common in the near future.
