Building experimental virtual routers with network processors

In this paper we describe the design and implementation of a system that uses network processors to support virtual and overlay routing. Because they are difficult to program and software development environments do not allow easy update, network processors are typically used as a replacement for hardware that performs fixed, well-known functions such as layer 3 forwarding. In contrast, experimental networking (e.g., overlay networks or multiple logical routers on a given interface) mandates rapid dynamic update of protocol software running on a network processor. To solve the problem, we created an underlying framework and programming interface that allows the dynamic extension of network processor forwarding capabilities without requiring the creation of an entirely new software image. The paper reports experience implementing our scheme