We introduce a programmable mechanism, called gathercast, to support the aggregation of packets without altering any of the routing or forwarding mechanisms of the Internet. Gathercast is based on active services framework and can be deployed incrementally. It works well within the current IP multicast model. We have implemented it in our own network. One of the aggregation mechanisms that we study in this paper is the combination of small packets using gathercast.
Small packets constitute a large fraction of packets in today's Internet.
Every packet requires a routing table lookup and incurs the same performance cost irrespective of the size of the packet. Web servers, in particular, are a leading cause of small packets. These ACKs are just 40 bytes in size. ICP queries are about 60 bytes in size. Simulation studies show that gathercast-enhanced ICP scales with the number of proxies with an order of magnitude reduction in the generated UDP messages.