Campus mobility refers to mobility within a single administrative domain, whether it is an entire university campus, a hospital, or a couple of conference rooms in a hotel. The main assumption in this model is that communication is within the campus (intranet), and no roaming exists across global Internet connectivity.
A good example of a campus intranet is a corporate campus. Consider a corporate facility of many units/departments, as shown in Figure 5-1. Assume that every unit/department has its own Local Area Network (LAN) segment (either Ethernet or 802.11, or both) and that the various segments are connected through a gateway router to a high-speed backbone, allowing the different departments to communicate with one another, albeit with proper security credentials. Note that this allows communication as long as the different hosts stay within their LAN, which can be limiting, especially in this mobile age.
Figure 5-1. Typical Corporate Campus
Deploying Mobile IP in this environment allows the network to become "campus mobile" capable, because Mobile IP client hosts can now roam around the campus and still maintain connectivity. This can be accomplished by various configurations, including simply installing Mobility Agent functionality on the gateway routers and installing Mobile IP client software on the portable hosts, for example, laptops, as shown in Figure 5-2.
Figure 5-2. Mobile Corporate Campus with Users Roaming Inside the Network Only
The first step toward simplifying Mobile IP deployments in the campus mobility environment is efficiently managing the security keys. This is accomplished by storing the security associations in an authentication, authorization, and accounting (AAA) server.