Control Message Aggregation in Group Communication Protocols

Reliable data transmission protocols between a sender and a receiver often use feedback from receiver to sender to acknowledge correct data delivery. Such feedback is typically sent as control messages by receiver nodes. Since sending of control messages involves communication overhead, many protocols rely on aggregating a number of control messages and sending them together as a single packet over the network. On the other hand, the delays in the transmission of control messages may reduce the rate of data transmission from the sender. Thus, there is a basic tradeoff between the communication cost of control messages and the effect of delaying them. We develop a rigorous framework to study the aggregation of control packets for multicast and other hierarchical network protocols. We define the multicast aggregation problem and design efficient online algorithms for it, both centralized and distributed.