OIF’s Coherent Common Management Interface Spec supports 400ZR

OIF has completed the Coherent Common Management Interface Specification (C-CMIS) Implementation Agreement (IA), which serves as an extension to the CMIS (QSFP-DD/OSFP/COBO) management specification, specifically targeting DCO modules.

“The C-CMIS IA is an important part of the developing 400ZR ecosystem,” said Ian Betty, Ciena and OIF Board Member. “It defines additional management registers, and monitors, together with new functionality, mechanisms, or behaviors, as needed.”

The C-CMIS IA provides register definition for coherent modules in pages and parameters that were previously reserved. Users that have previously implemented software to manage optical modules using CMIS will be able to quickly add support for these coherent pages and parameters. This release, which augments the existing CMIS specification which focused on addressing direct detect client optics, is targeted at the 400ZR application.

The technology and complexity of coherent modules requires additional monitoring parameters for use in field applications. This additional monitoring is primarily focused on Forward Error Correction (FEC) monitoring and optical/analog monitoring including items like Chromatic Dispersion, Differential Group Delay and Electrical Signal to Noise Ratio (eSNR). The C-CMIS IA provides specifications to monitor the standard parameters in a normative manner while taking advantage of the flexibility of the CMIS specification to monitor any additional proprietary parameters. 

“The current IA is focused on supporting the OIF 400ZR IA, which supports a single data path with eight-lane host electrical interface for a 400GBASE-R PCS signal and a single-lane 400G coherent media interface (with a new signal format called 400ZR),” explained Betty. “However, we expect future versions to include more complex Metro modules and may even extend these management features to other form factors.”

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