Small packets constitute a large fraction of packets in the Internet. Gathercast is a network layer service that combines small packets going to the same destination into a single packet, reducing the number of packets in the network and saving computations at intermediate routers. In this paper, we propose a new model for gathercast using active network techniques. With this model, gathercast is built throughout the network with low overhead, service parameters can be dynamically adjusted and end-user applications obtain benefits from gathercast without knowing its existence. We also present an implementation of the active gathercast.