Parallel TCP Sockets: Simple Model, Throughput and Validation
Eitan Altman, Dhiman Barman, Bruno Tuffin, Milan Vojnović · 2006
We found a formula for aggregate throughput of arbitrarily given number of competing additive-increase, multiplicative-decrease connections (TCP congestion avoidance mode) for a bottleneck, under assumption that loss events over connections are non synchronized. The formula captures throughput-deficiency due to the additive-increase and multiplicative-decrease adaptation. The formula suggests that already a few connections are sufficient to almost entirely eliminate this throughput deficiency. The result reveals the aggregate throughput insensitivity on the way losses are assigned over competing connections over time, for any given number of competing connections. The result is validated by simulations and Internet measurements. The latter validates the model in cases when analysis assumptions are met, but also encounters cases of the throughput deficiency due to synchronization of loss events and the receiver window constraint. The results would inform on the throughput efficiency of parallel TCP transfers, an approach used widely for bulk data transfer.