Exposing the network: support for topology-sensitive applications

One of the traditional goals of networking has been to hide details of network topology from end users. As networks become larger and more heterogeneous, however, situations arise in which the ability to identify particular topological properties enables capabilities and performance that are difficult to achieve with a purely “black box” interface to network topology. Examples of such situations include deployment of active networking functionality to strategic points (e.g., upstream from a lossy link) or the construction of a secure overlay topology on a network with selective support for IP security. On the other hand, an approach that “opens up” the network without constraints seems neither necessary nor practical. We therefore propose a method to query and synthesize network information that allows constrained programmability. We demonstrate the method on a set of examples, and we discuss our implementation within an active networking environment