  Large-scale video conferencing services incur significant network cost while
serving surging global demands. Our work systematically explores the
opportunity to offload a fraction of this traffic to the Internet, a cheaper
routing option offered already by cloud providers, from WAN without drop in
application performance. First, with a large-scale latency measurement study
with 3.5 million data points per day spanning 241K source cities and 21 data
centers across the globe, we demonstrate that Internet paths perform comparable
to or better than the private WAN for parts of the world (e.g., Europe and
North America). Next, we present Titan, a live (12+ months) production system
that carefully moves a fraction of the conferencing traffic to the Internet
using the above observation. Finally, we propose Titan-Next, a research
prototype that jointly assigns the conferencing server and routing option
(Internet or WAN) for individual calls. With 5 weeks of production data, we
show Titan-Next reduces the sum of peak bandwidth on WAN links that defines the
operational network cost by up to 61% compared to state-of-the-art baselines.
We will open-source parts of the measurement data.
