1. Background
400ZR and OpenZR+ are the two mainstream 400G coherent module standards, both in QSFP-DD form factor but with different positioning and interoperability.
2. 400ZR
Defined by the OIF, uses 16QAM modulation, typical reach 80-120km, targets DCI with multi-vendor interoperability and plug-and-play.
3. OpenZR+
Defined by the OpenZR+ MSA, supports QPSK/8QAM/16QAM, flexible reach of 40-280km, and rates of 100G/200G/300G/400G — for mixed DCI and metro scenarios.
4. Comparison
- Interoperability: 400ZR interoperates better in DCI; OpenZR+ is more flexible but with narrower interop scope.
- Reach: OpenZR+ covers a wider range (incl. long-haul QPSK).
- Use case: choose 400ZR for pure DCI; OpenZR+ for metro+DCI mix.
