Abstract
IP multicast is an efficient point to multipoint protocol. However, a number of scenarios exist where the reverse mechanism of multi-point to point protocol is needed. Gathercast is a mechanism by which packet flows from a large number of nodes can be gathered as the packets are routed towards the gatherer. Gathercast uses transformer tunnels [1] at routers to provide a mechanism for aggregating packets directed towards a node. Increased goodput for applications that need flow aggregation can be obtained by using any of a number of transformation functions such as recombination of small packets, compressing data, rate control, replication removal, and so on, along with a distribution tree. Gathercast works well in conjunction with the current IP multicast model. Simulations results for gathercast show that using aggregators along a gather tree improves the network utilization.