The Prospect of Inter-Data-Center Optical Networks

Mega data centers and their interconnection
networks have drawn great attention in recent
years because of the rapid public adoption of
cloud-based services. The unprecedented
amount of data that needs to be communicated
between data centers imposes new requirements
and challenges to inter-data-center optical networks.
In this article, we discuss the traffic
growth trends and capacity demands of Google’s
inter-data-center network, and how they
drive the network architectures and technologies
to scale capacities and operational ease on existing
fiber plants. We extensively review recent
research findings and emerging technologies,
such as digital coherent detection and the flexgrid
dense wavelength-division multiplexed channel
plan, and propose practical implementations,
such as C+L-band transmission, packet and
optical layer integration, and a software-defined
networking enabled network architecture for
both capacity and operational scaling. In addition,
we point out a few critical areas that require
more attention and research to improve efficiency
and flexibility of an inter-data-center optical
network: optical regeneration, data rate mismatch
between Ethernet and optical transport,
and real-time optical performance monitoring.

• Networking