Data Center Dominates OFCApril 18, 2017
Author: Loring Wirbel
Thanks to greater optimism among optical-component vendors targeting the data center, attendance at the 2017 Optical Fiber Communication Conference (OFC) rose to nearly 15,000. This increase was in spite of the limited volume for metro and long-haul links. But fragmentation in the market for VCSELs, silicon photonics, and embedded on-board optics hinders the effort to bring optical-link costs closer to that of twinax-copper direct-attach cabling (DAC). Urs Holsze, director of technology infrastructure at Google, warned in a keynote speech that a “boutique artisan” manufacturing mentality continued to dominate the market for multisource-agreement (MSA) modules.
Although some component specialists for 2–40km reach emphasized specifications that make their products appropriate for data-center interconnects, OFC attendees focused mainly on very short reach (VSR) to 2km—the realm of the data center. Drawing the biggest crowds were demonstrations of single-wavelength 100Gbps lanes, as well as presentations by the Consortium for On-Board Optics (COBO). But many attendees realized that the workhorses for near-term data-center designs are pluggable optical modules and 50Gbps serial lanes based on PAM4 modulation.
The conference followed the pattern of recent years in centering on a battle over MSA form factors. This year, more than 60 companies followed Cisco’s lead in touting double-density QSFP (QSFP-DD) as the follow-on to QSFP28; the newer technology preserves compatibility with the 28Gbps form factor while offering eight electrical lanes for 200GbE using 25Gbps NRZ or 400GbE using 50Gbps PAM4. Challenging QSFP-DD was a longer and deeper MSA: octal small-form pluggable (OSFP), which integrates a heat sink that allows an octal module to dissipate 15W. A coalition of 80 companies led by Google and Arista Networks is backing OSFP. This year, however, optical-component vendors went out of their way to characterize the QSFP-DD/OSFP relationship as one of “friendly complementarity.”
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