The exponential growth of the Internet and the inexorable increase in native computing power of laptop computers and other digital wireless data communication devices has brought the need for mobile networking into sharp focus. As network services proliferate and become available ubiquitously, every network device will take advantage of mobile networking technology to offer maximum flexibility to the customers needing those devices. To understand the contrast between the current realities of IP connectivity and future possibilities, consider the transition toward mobility that has occurred in telephony over the past 20 years. An analogous transition in the domain of networking, from dependence on fixed points of attachment to the flexibility afforded by mobility, has just begun. Network mobility is enabled by Mobile IP, which provides a scalable, transparent, and secure solution. It is scalable because only the participating components need to be Mobile IP aware—the Mobile Node and the endpoints of the tunnel. No other routers in the network or any hosts with which the Mobile Node is communicating need to be changed or even aware of the movement of the Mobile Node. It is transparent to any applications while providing mobility. Also, the network layer provides link-layer independence; interlink layer roaming, and link-layer transparency. Finally, it is secure because the set up of packet redirection is authenticated.