  Several Traffic Engineering (TE) techniques based on SDN (Software-defined
networking) proposed to resolve flow competitions for network resources.
However, there is no comprehensive study on the probability distribution of
their throughput. Moreover, there is no study on predicting the future of
elephant flows. To address these issues, we propose a new stochastic
performance evaluation model to estimate the loss rate of two state-of-art flow
scheduling algorithms including Equalcost multi-path routing (ECMP), Hedera
besides a flow congestion control algorithm which is Data Center TCP (DCTCP).
Although these algorithms have theoretical and practical benefits, their
effectiveness has not been statistically investigated and analyzed in
conserving the elephant flows. Therefore, we conducted extensive experiments on
the fat-tree data center network to examine the efficiency of the algorithms
under different network circumstances based on Monte Carlo risk analysis. The
results show that Hedera is still risky to be used to handle the elephant flows
due to its unstable throughput achieved under stochastic network congestion. On
the other hand, DCTCP found suffering under high load scenarios. These outcomes
might apply to all data center applications, in particular, the applications
that demand high stability and productivity.
