Mobile IPv6 and cellular telephony

We emphasize the need for IPv6 addressability for handling the billion-plus wireless IP devices that are expected to be sold within the next three years. Since these devices are wireless and therefore mobile, they will derive great benefit from Mobile IPv6. To understand this requires consideration of the specific features included within IPv6 for support of mobile devices. Mobile IPv6 was designed to be a natural outgrowth of Mobile IP for IPv4, just as IPv6 itself was designed to be a natural outgrowth of IPv4. In each case, the newer protocol has benefited from the lessons learned during the implementation and deployment of its forerunner. Mobile IP for IPv4 is already several years ahead of Mobile IPv6 along the IETF standards track. For this reason, there are a number of features already well understood for IPv4 mobility that are not as well understood for IPv6 mobility. We offer some ideas about how the IPv4 features are likely to migrate to IPv6 over the next