Microsoft, vendors to define board interfaces
SAN JOSE, Calif. – Optical communications will take a step closer to server and switch motherboards thanks to a new alliance that will develop interconnect standards. Microsoft has rallied a group of 14 data center vendors to form the Consortium for On-Board Optics (COBO) that hopes to release its first specifications in a year.
COBO will “define electrical interfaces, management interfaces, thermal requirements and pin-outs…[for] optical modules that can be mounted or socketed on a network switch or adapter motherboard,” according to a press statement from the group. It is initially expected to focus on 100 and 400G links.
“The goal is to bring the goodness of faceplate pluggable optics like SFP+ and QSFP+ to the on-board optics market,” said Brad Booth, COBO Chair and principal architect for Microsoft’s Azure Global Networking Services, in an email exchange with EE Times.
Bringing optical connections to the board helps switch makers break through current limits of how many optical ports can fit on the front panel of a system. “This will permit system OEMs to mount the optical modules in the same manner that they mount switch ICs and in a location that benefits power consumption and heat dissipation,” Booth said.
Currently vendors use a variety of proprietary formats for the so called on-board or embedded optics. The COBO specs aim to create a level playing field in which data center operators can choose interchangeable modules from multiple companies.
Members of COBO so far are Arista Networks, Broadcom, Cisco Systems, Coriant, Dell, Finisar, Inphi, Intel, JDSU, Juniper Networks, Luxtera, Mellanox Technologies, Microsoft, Oclaro, Ranovus, Source Photonics and TE Connectivity.
“On-board optics permit greater switch radix with lower power consumption, which is really important as we continue to increase speed and bandwidth,” Booth said.
“The overall market for such optical modules is relatively small, but this initiative has the potential to increase interest,” said Chris Cole, a director of transceiver engineering at Finisar, in a separate email exchange.
Next page: From VCSELs to silicon photonics
From VCSELs to silicon photonics
The COBO spec will cover a variety of technologies. They include VCSEL-based boards such as those made by Finisar and emerging designs using silicon photonics such as those from Mellanox and the members of its Open Optics alliance supporting a version of silicon photonics based on wavelength division multiplexing.
“The combination of open electrical and optical specifications holds the promise of an on board optical module that can provide connectivity to an entire rack of servers through a single fiber with the flexibility to choose the best and most cost-effective technology from a choice of interoperable vendors,” said Kevin Dieirling, vice president of marketing at Mellanox, also in an email exchange.
“Silicon photonics can definitely take advantage of on-board optics, but it isn’t limited to just that technology,” Booth said.
The move is another example of how data center giants are driving the technical road maps for infrastructure systems. “Cloud data center networks are setting the pace for switch ASIC and high speed optics innovations,” said Thomas Scheibe, senior director of product management for Cisco’s Insieme Business Unit, speaking in the COBO press release.
Interestingly, COBO consists of a broad swath of competing system and component vendors but only one end user, Microsoft. Although the company is part of the Facebook-led Open Compute Project (OCP), this alliance does not include Microsoft’s data center rivals such as Amazon, Facebook and Google
“They were invited,” said Booth. “They have their own business reasons for not wanting to join at this time,” he added.
Just how data center operators add what sort of optical links to their networks is becoming a point of differentiation. A lead Facebook network engineer said he plans to announce at OFC his plans to adopt silicon photonics.
Cisco, Intel, Luxtera and Mellanox are among a handful of vendors trying to get data centers to adopt their different approaches to silicon photonics. Intel announced its plans for silicon photonics at a past OCP event as the venue, but its products have been delayed for a year.
— Rick Merritt, Silicon Valley Bureau Chief, EE Times