Exploring the Pub/Sub Routing & Forwarding Space

We envision an information-centric future Internet where the network is built around named pieces of data instead of explicitly addressable hosts. One clear way of implementing information-centric networking is using publish and subscribe (pub/sub) operations instead of the send and receive primitives. Internet-like pub/sub networking requires completely different routing protocols and forwarding mechanisms compared to those that are extensively used today. Consequently, we are facing a clean-slate design exercise, where we should start our adventure by exploring the new design space. We identify four key metrics (signalling overhead, state in nodes, information in packets and routing stretch) to help us evaluating the different proposals. We present a general five-step approach for routing in pub/sub networks. The presented approach is recursive, so it can be repeated as many times as necessary until we reach manageable sized problem instances. The final part of the mechanism is to glue together the created and assigned forwarding structures to the publication to ensure that all interested subscribers at any domains in the network will get the requested data.