This paper is an attempt to quantify the performance differences for content-based multicast implemented inside the overlay routing algorithm or built on top of the simple API provided by the routing layer. We focus on overlay networks designed for peer-to-peer distributed hash table (DHT) applications where content-based multicast is most applicable. In particular we study the Content Addressable Networks (CAN) and Chord routing algorithms. It is our conjecture that similar results would be obtained through other protocols such as Pastry and Tapestry.
We show that it is feasible and in some ways more flexible to provide content-based multicast above the routing layer with only a modest gain in latency.