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After 400GbE, IEEE Studies PHYs

July 11, 2017

Author: Loring Wirbel

The IEEE’s 802.3bs standard for 200Gbps and 400Gbps Ethernet is racing to the finish line with surprising consensus; the organization may ratify it as early as September. But tempering any notion that a study group for 800GbE could be created immediately afterward is the 802.3 committee’s broad belief that participants must carefully study various PHY options.

John D’Ambrosia, 802.3bs chair, said the 802.3 New Ethernet Applications (NEA) discussion group will likely be the one to explore new PHYs. That group, however, doesn’t propose standards. More immediately, D’Ambrosia will present a call for interest at the IEEE plenary session in Berlin for new optical PHY standards that operate beyond 10 km for 50GbE, 200GbE, and 400GbE.

Depending on advances in forward error correction (FEC) as well as modulation, 800GbE PHYs using 16x50Gbps, 8x100Gbps, and perhaps 4x200Gbps are feasible. Careful analysis of such PHYs in dedicated study groups may prove more fruitful than a catchall 800GbE task force. But skeptics insist the apparently slow IEEE response to 25GbE and 2.5/5GbE proposals led industry consortia to promote these Ethernet speeds anyway.

Hyperscale data centers will probably need to add 800GbE and 1.6TbE backbones by 2020, but the cautious effort to create new PHY and MAC standards isn’t necessarily misguided. Once optical components for 500m and beyond become available, a dedicated 800GbE standard may make sense. OEMs and data-center managers are interested in a 500m SMF solution at 800GbE, but they consider it too limited for a multifaceted 800GbE standard. If they believe a dedicated 800GbE standard is advantageous, a call for interest could quickly lead to a new study group. In the meantime, most participants see the 802.3 NEA discussion group as a good means of building consensus on future Ethernet projects.

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