PLAN is a resource-bounded functional programming language that uses a form of remote procedure call to realize active networking. PLAN is designed to be a public, authentication-free layer in the Active Network hierarchy. For this reason, we have limited the expressive power of PLAN in order to guarantee that all programs will terminate, thus reasonably permitting a router to run any PLAN program. However, PLAN can also be used as a “glue” layer which allows access to higher-level services.