SANTA CLARA, Calif. - Data center networks are starting a migration to 400G Ethernet this year that a new class of optical modules will accelerate in 2020. The next big leap will be to 800G if IEEE standards and optics fall in line, said Arista co-founder and networking veteran Andreas Bechtolsheim. 

The world’s largest data centers are driving the demand with bandwidth requirements rising more than 50% a year, said Bechtolsheim whose company sells them switches.  

“They are not investing for nothing--more features such as AI bring them more products and eyeballs. [Meanwhile] enterprise workloads aren’t changing that much—Oracle's database won’t run much faster next year, so their current networks are OK,” he said in response to a question after a keynote at Hot Interconnects here. 

Big data centers will be the main consumers of 400G links (Dell'Oro Group)
Big data centers will be the main consumers of 400G links (Dell'Oro Group)
 

As many as 800,000 400G Ethernet ports could ship this year, mainly for long haul and metro networks. But next year that could rise to as many as three million 400G ports thanks largely to 400G-ZR/ZR+, a new class of coherent, pluggable optical modules supporting dense wavelength-division multiplexing. 

“ZR will be a game changer,” for several reasons, he said. A half dozen vendors will ship the modules next year at prices of about $4,000 or $10 per Gbit/second, an order of magnitude below the alternatives. And the ZR+ versions will handle up to 20W, cover 10-1,000km distances, and support next-gen 100G serdes, compared to alternatives limited to 15W and 50G serdes. 

The ZR modules will enable a fast transition to 800G versions within two years, potentially getting ahead of IEEE standards for Ethernet controllers, Bechtolshiem said. Data centers will be quick to move to the new modules to save cost, thus he expects to ship switches supporting such modules as early as next year.  

The IEEE could simply double lane speeds in its 802.3bs standard to enable supporting 800G switch chips, Bechtolsheim added. He first called for an 800GE spec in February 2017.

Bechtolsheim’s crystal ball gets fuzzy beyond systems supporting 112G serdes in 2021. He sees difficulties both in extending serdes beyond 112G and in upgrading optical modules and switches to a 1.6 Tbit/s step. 

Dell'Oro forecasts a fast revenue ramp for 400G Ethernet (above). Bechtolsheim predicts (below) the 50G/lane Ethernet standard will be so short lived the IEEE could have skipped it.
Dell'Oro forecasts a fast revenue ramp for 400G Ethernet (above). Bechtolsheim predicts (below) the 50G/lane Ethernet standard will be so short lived the IEEE could have skipped it.