The 60GHz wireless technology that is now emerging

has the potential to provide dense and extremely fast connectivity

at low cost. In this paper, we explore its use to relieve hotspots

in oversubscribed data center (DC) networks. By experimenting

with prototype equipment, we show that the DC environment is well

suited to a deployment of 60GHz links contrary to concerns about

interference and link reliability. Using directional antennas, many

wireless links can run concurrently at multi-Gbps rates on top-ofrack

(ToR) switches. The wired DC network can be used to sidestep

several common wireless problems. By analyzing production traces

of DC traffic for four real applications, we show that adding a small

amount of network capacity in the form of wireless flyways to the

wired DC network can improve performance. However, to be of

significant value, we find that one hop indirect routing is needed.

Informed by our 60GHz experiments and DC traffic analysis, we

present a design that uses DC traffic levels to select and adds flyways

to the wired DC network. Trace-driven evaluations show that

network-limited DC applications with predictable traffic workloads

running on a 1:2 oversubscribed network can be sped up by 45%

in 95% of the cases, with just one wireless device per ToR switch.

With two devices, in 40% of the cases, the performance is identical

to that of a non-oversubscribed network.

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Publisher  ACM SIGCOMM

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