Exploitation of optical interconnects in future server architectures

TLDR

Optical fiber links are ubiquitous for long‑distance networking and are increasingly considered for high‑bandwidth, short‑distance links such as I/O, memory, and system buses, raising packaging, power, and cost concerns that could reshape high‑end server design. This paper reviews the levels of a server interconnect hierarchy and the current status of optical interconnect technology at each level. It also examines the potential impacts of optical interconnects on future server designs.

Abstract

Optical fiber links have become ubiquitous for links at the metropolitan and wide area distance scales, and have become common alternatives to electrical links in local area networks and cluster networks. As optical technology improves and link frequencies continue to increase, optical links will be increasingly considered for shorter, higher-bandwidth links such as I/O, memory, and system bus links. For these links closer to processors, issues such as packaging, power dissipation, and components cost assume increasing importance along with link bandwidth and link distance. Also, as optical links move steadily closer to the processors, we may see significant differences in how servers, particularly high-end servers, are designed and packaged to exploit the unique characteristics of optical interconnects. This paper reviews the various levels of a server interconnect hierarchy and the current status of optical interconnect technology for these different levels. The potential impacts of optical interconnect technology on future server designs are also reviewed.