Concast, design and implementation of an active network service

Concast is a network layer service that provides many-to-one channels: mult iple sources send messages toward one destination, and the network delivers a single "merged" copy to that destination. As we have defined it, the ser vice is generic but the relationship between the sent and received messages can be customized for particular applications. In this paper, we describe the concast service and show how it can be implemented in a backward-compat ible manner in the Internet, We describe its use to solve a problem that ha s eluded scalable end-system-only solutions: collecting feedback in multica st applications. Our preliminary analysis of concast's effectiveness shows that it provides significant benefits, even with partial deployment, We arg ue that concast has the characteristics needed for a programmable service t o be widely accepted and deployed in the Internet.