Nanosecond Time Synchronization for Optical Data Center Networks

Optical data center networks (DCNs) are renovating the infrastructure design for the cloud in the post-Moore's law era. The fact that optical DCNs rely on optical circuits of microsecond-scale durations makes nanosecond-precision time synchronization essential for the correct functioning of routing on the network fabric. However, current studies on optical DCNs neglect the fundamental need for accurate time synchronization. In this poster, we bridge the gap by developing Nanosecond Optical Synchronization (NOS), the first nanosecond-precision synchronization solution for optical DCNs general to various optical hardware. NOS builds clock propagation trees on top of the dynamically reconfigured circuits in optical DCNs, allowing nodes to seek better sync parents throughout time. It leverages the real-time error bounds of nodes to guide the tree-building process, minimizing synchronization errors. Our simulations demonstrate a synchronization accuracy of 23 ns in a 192-node configuration, surpassing the accuracy of state-of-the-art synchronization protocols in electrical DCNs of the same scale.