Google’s Datacenter Optical Circuit Switches and Jupiter network fabric
Google’s data centers are unlike any other. It seems they have windows like normal houses because as from the last SIGCOMM’22 presentation, they took their SPINE switches and threw them right out of that window.
Google worked on the Micro Electro Mechanical Systems (MEMS) for years in order to build an Optical Circuit Switch (OCS) that would enable dynamic reconfiguration of optical connections between switches in the data center. Optical Circuit Switch enables on-the-fly data center fabric aggregation block switch connections reconfiguration without the need for physical rewiring. And most interestingly, the usage of Software-Defined Networking (SDN) traffic engineering, enables aggregation block switches to be directly connected and completely removes the need for those bulky Spine switches that were connecting aggregation block switches in CLOS topologies.
Spine switch roles are basically replaced with OCS devices for smart, dynamic and direct interconnections of Leafs. SDN is used for BUM traffic handling (Broadcast, unknown-unicast and multicast traffic) that was the other important spine role.
Google paper (Jupiter Evolving: Transforming Google’s Datacenter Network via Optical Circuit Switches and Software-Defined Networking) that was presented at the SIGCOMM’22 conference describes how getting rid of Spines, and smart traffic handling with SDN, enabled the Jupiter fabric to get up to 5x higher speed and capacity and 40% reduction in power consumption in relation to similar CLOS topology datacenter fabrics.