With the open and standard programmatic interface and the flexibility
of controlling network, Software Defined Network (SDN) can obviously
simplify and integrate operation and business support systems. As a
consequence, to satisfy the rising switching demand in the data center
network, it is a good option to adopt SDN technology. In addition,
current architecture of data center network is far from ideality,
which results in the low utilization rate in bandwidth resource. For
example, mice flow cannot be well effectively served in the
conventional Wavelength Division Multiplexing (WDM) optical network
with at least 50GHz spectrum interval. From a data center network
perspective, it is necessary to further improve the resource
utilization efficiency and the flexibility of coping with different
traffic. This document described an optical data center interconnect,
which comprises both the fixed and flexible grid transceivers. A
traffic monitor is implemented in the SDN-based data center network to
evaluate the coming traffic demands and allocate appropriate spectrum
for the request. For instance, mice flow can be served by fixed grid
transceivers, well the elephant flows can be transmitted by the flexi-
grid transceiver using multiple subcarriers to form a superchannel.
Thus, spectrum efficiency is optimized and bandwidth utilization is
improved dramatically.