What Is OpenZR+?

OpenZR+ was designed to expand the application space for a coherent solution in a small form factor pluggable module. OpenZR+ can help address not only a broader range of hyperscale data center applications for higher-performance edge and regional interconnects, but also some emerging carrier transport architectures.

Key Features:

  • Higher performance
  • Regional and long-haul reaches
  • Ethernet client multiplexing
  • 100G/200G/300G/400G transmission

As illustrated in the above image, OpenZR+ is a combination of two industry standardization efforts created to maintain the simple Ethernet-only host interface of 400ZR while adding support for features such as:


  1. Higher coding gain using oFEC from the Open ROADM standard, which extends the reach capability;
  2. Multi-rate Ethernet, which enables the multiplexing of 100GbE and 200GbE clients over the line-side link, providing optimization options for the switch/router equipment to channelize the traffic over the transport link;
  3. 100G, 200G, 300G or 400G line-side transport links (using QPSK, 8QAM, or 16QAM modulation), which enables reach/capacity optimization over various fiber links; and
  4. Higher dispersion tolerance. OpenZR+ targets these enhanced capabilities in the same QSFP-DD or OSFP form factors used for 400G client optics in high density switch applications

Benefits to the users and the industry

400G pluggable modules represent an architectural change in high-bandwidth data center interconnects because they can be plugged directly into switches and routers offering the same density for both coherent DWDM and client optics in the same chassis. Paired with Open Line System (OLS) architectures, network operators would be able to eliminate external transport equipment in their network. This architectural change helps network operators support their growing bandwidth demands in a more cost-efficient manner. 

By establishing an OpenZR+ specification, we believe the industry will benefit from multi-vendor interoperability, which may pave way for the development of OpenZR+ modules in a QSFP-DD or OSFP form factor with enhanced performance and functionality.

OpenZR+ will be designed to enable network operators to address a wide range of applications using this interoperable solution

OpenZR+ Applications

OpenZR+ provides an open, flexible and interoperable coherent solution in a small form factor pluggable module that addresses hyperscale data center applications for higher-performance edge and regional interconnects, as well as potential future carrier applications.

Reduce operational complexity
Because OpenZR+ is derived from existing standards, all network operators can operationally benefit from interoperability among multiple suppliers that adopt OpenZR+. Module suppliers can also benefit from OpenZR+ by supporting a broader range of applications

For Hyperscale Networks: Wider Geographical Extension
The higher performance of OpenZR+ can benefit hyperscale network operators by enabling a wider geographical extension of the physical connections to cover DCI Edge and regional interconnects.

Hyperscale line systems with 75GHz DWDM grid spacing can also benefit from modules utilizing OpenZR+. Due to filtering and cross-talk effects, the optical signal can degrade over 75GHz grid spacing. The additional gain from oFEC in OpenZR+ can be used to compensate for these additional penalties.

For Carrier and MSO networks: Optimize Network Efficiency

Carrier efforts to create a data center topology, such as CORD within the Open Networking Foundation (ONF), may also benefit from OpenZR+ utilizing this Ethernet-centric coherent optical solution. With OpenZR+, these network operators can utilize these architectures to address a range of applications from access aggregation to regional and long-haul, achieving additional benefits of volume and scale.

Additional Resources:
Article: Hamada, M.; Srivastava, A.; Swail, S.; Williams, T.; Wu, X. (2019). OpenZR+ Offers Performance and Interoperability. Optical Connections
Article: Park, E. (2019). Advancing Coherent Interoperability with OpenZR+. Optical Connections

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