Mobility Concepts and Principles
There are 10 types of people: those who understand binary and those who do not understand it. –Anonymous
In this chapter, we will discuss in detail the basic concepts that define mobility in the Internet. Our intent is to expose the reader to concepts and principles that underlie mobility. We will look at the roaming and handover problems, and approaches being considered to solve them. We also look at the core Internet principles and how the different approaches compare against them.
4.2 ROAMING AND HANDOVER TOGETHER CONSTITUTE THE MOBILITY PROBLEM
When a mobile node moves to a new location, it must satisfy a number of requirements before it can begin to receive packets. Some of the requirements can, depending on circumstances and the roaming strategy used, be satisfied without additional operations on the mobile device. These requirements include:
• Establishing a link
• Fulfilling conditions for access control to the link
• Acquiring a topologically correct IP address
• Maintaining resolvability of its Domain Name Space name into a reachable IP address
• Enable traversal of the local firewall
The amount of work required to satisfy these requirement varies, depending on the roaming strategy selected. For the case of Mobile IP, for instance, the mobile device easily maintains resolvability of its DNS name since the point ...