The Optical Internetworking Forum (OIF) has published the Implementation Agreement (IA) for a 400ZR coherent optical interface.
This agreement, the first OIF project with a scope that focused on interoperability at a specific distance, was developed to create an interoperable, low-cost 400 Gigabit coherent interface. It addresses two applications: amplified, point-to-point DWDM links with reaches of 120 km or less; and unamplified, single wavelength links with a loss budget of 11dB
The project was initiated when large-scale data centre operators and their suppliers approached OIF to develop an interoperable coherent interface that transports 400GbE over longer distances. Traditional network operators also became interested in 400ZR for their metro needs. Based on their different requirements, OIF developed specs and tweaked the channel requirements so the IA would benefit both data centre and network operators. While developing the IA, OIF also collaborated with other standards bodies.
Mark Filer, principal optical engineer at Microsoft Azure explained: ‘400ZR is a key enabler of Microsoft’s regional architecture for the 400G generation. The creation of a multi-vendor, interoperable coherent interface to meet these needs would not have been possible without the extensive work and cooperation of OIF members and leadership.
The IA aims to enable interoperable, cost-effective, 400Gb/s implementations based on single-carrier coherent DP-16QAM modulation, low-power DSPs supporting absolute (Non-Differential) phase encoding/decoding, and a Concatenated FEC (C-FEC) with a post-FEC error floor <1.0E-15. 400ZR operates as a 400GBASE-R PHY.
No restriction on the physical form factor is implied by the IA (QSFP-DD, OSFP, COBO, CFP2, CFP8), but the specifications target a pluggable DCO architecture with port densities equivalent to grey client optics.
