  To improve the application-level communication performance, scheduling of
coflows, a collection of parallel flows sharing the same objective, is
prevalent in modern data center networks (DCNs). Meanwhile, a hybrid-switched
DCN design combining optical circuit switches (OPS) and electrical packet
switches (EPS) for transmitting high-volume traffic and low-volume traffic
separately has received considerable research attention recently. Efficient
scheduling of coflows on hybrid network links is crucial for reducing the
overall communication time. However, because of the reconfiguration delay in
the circuit switch due to the ultra-high transmission rate and the limitation
of bandwidth in the packet switch, coflow scheduling becomes increasingly
challenging. The existing coflow scheduling algorithms in hybrid-switched DCNs
are all heuristic and provide no performance guarantees. In this work, we
propose an approximation algorithm with the worst-case performance guarantee of
2+ \lambda?, where \lambda? is a factor related to system parameters and demand
characteristics, for single coflow scheduling in hybridswitched DCN to minimize
the coflow completion time (CCT). Extensive simulations based on Facebook data
traces show that our algorithm outperforms the state-of-the-art schemes
Solstice by 1.14? and Reco-Sin by 1.42? in terms of minimizing CCT.
