Free Space Intra-Datacenter Interconnects Based on 2D Optical Beam Steering Enabled by Photonic Integrated Circuits

Charidimos Chaintoutis,Paul Dijk,Dimitris Syvridis,Jerome Bourderionnet,Behnam Shariati,Ioannis Tomkos,Adonis Bogris,Chris Roeloffzen

doi:10.3390/photonics5030021

Abstract

Data centers are continuously growing in scale and can contain more than one million servers spreading across thousands of racks; requiring a large-scale switching network to provide broadband and reconfigurable interconnections of low latency. Traditional data center network architectures, through the use of electrical packet switches in a multi-tier topology, has fundamental weaknesses such as oversubscription and cabling complexity. Wireless intra-data center interconnection solutions have been proposed to deal with the cabling problem and can simultaneously address the over-provisioning problem by offering efficient topology re-configurability. In this work we introduce a novel free space optical interconnect solution for intra-data center networks that utilizes 2D optical beam steering for the transmitter, and high bandwidth wide-area photodiode arrays for the receiver. This new breed of free space optical interconnects can be developed on a photonic integrated circuit; offering ns switching at sub-μW consumption. The proposed interconnects together with a networking architecture that is suitable for utilizing those devices could support next generation intra-data center networks, fulfilling the requirements of seamless operation, high connectivity, and agility in terms of the reconfiguration time.

Highlights

Warehouse scale data centers (DCs) host several hundreds of thousands of servers and other equipment, spreading across thousands of racks that are interconnected by an underlying intra-data center network architecture
The traditional way of designing DCNs, through the use of electrical packet switches in a multitier topology, has a fundamental weakness, namely that it has to be decided in advance whether to provide overprovisioned or oversubscribed interconnects between top of rack (ToR) switches
We propose a cylindrically shaped cluster with the racks placed on the direct line of sight (LoS)

Summary

Introduction

Warehouse scale data centers (DCs) host several hundreds of thousands of servers and other equipment, spreading across thousands of racks that are interconnected by an underlying intra-data center network (intra-DCN) architecture. The traditional way of designing DCNs, through the use of electrical packet switches in a multitier topology, has a fundamental weakness, namely that it has to be decided in advance whether to provide overprovisioned or oversubscribed interconnects between top of rack (ToR) switches The former choice is quite expensive, whilst the latter leads to poor performance when congestion emerges. The proposed interconnection solution can support radical change in intra-DCN topologies, enabling random graph topologies Such an architecture can be supported by a new-breed of FSO nodes utilizing novel transceivers, which can be developed on a photonic integrated circuit (PIC), offering a significant reduction in the cost, footprint, and switching speed. The proposed FSO interconnects could form the basis of a reconfigurable intra-DCN that could fulfil the properties of seamless operation, high connectivity (direct communication from a rack to many others) and agility in terms of the reconfiguration time

Al Properties of the Proposed Optical Beam Steering

Optical

Power Budget

Inter-Data Center Networking Scheme and Results

Proposed

Conclusions