400G ZR vs. Open ROADM vs. ZR+

In the dynamic realm of global optical networks, innovation remains paramount to meet the evolving needs of network operators. As demands for maximizing fiber utilization and minimizing data transmission costs escalate, coherent optical transmission has emerged as a linchpin solution. Today, coherent pluggable solutions spanning from 100G to 400G data rates offer compact and power-efficient options for data center operators. Among these, the 400G ZR, Open ROADM, and ZR+ standards stand out, each offering unique benefits and applications. This exploration aims to distill key insights into these standards, empowering decision-makers with essential knowledge for network optimization and strategic planning.

Understanding 400G ZR vs. Open ROADM vs. ZR+

Depending on the network setups and the unique data transmission requirements, data centers can choose to deploy any of the coherent pluggable solutions. We've highlighted key facts about these solutions below, from definitions to differences and applications.

What Is 400G ZR?

400G ZR sets a standard for transferring 400 Gigabit Ethernet over a single optical wavelength, utilizing technologies like DWDM (dense wavelength division multiplexing) and higher-order modulation such as 16 QAM. Developed by the Optical Interoperability Forum (OIF), this cost-effective solution establishes an interoperable interface for 400G data transmission, marking one of the initial standards in this domain.

• The primary benefits of 400G ZR stem from its adoption of state-of-the-art coherent optical technology, enabling robust support for high-capacity point-to-point data transport over DCI links spanning distances between 80 and 120km.

• Moreover, the intentionally restricted performance of 400ZR modules ensures cost efficiency and compact physical dimensions. This strategic decision streamlines integration into smaller modules like the Quad Small Form-Factor Pluggable Double-Density (QSFP-DD) and Octal-Small Form-Factor Pluggable (OSFP), all while maintaining power consumption levels that meet industry standards.

FS 400G ZR module offers superior performance and reliability, tested rigorously for quality assurance. With DWDM capability and hot-pluggable QSFP-DD form factor, it adapts wavelengths for enhanced network flexibility. Perfect for DCI applications, it ensures high-speed transmission over optical links. Upgrade your network with FS's 400G ZR module for unparalleled efficiency and scalability.

Figure 1 : FS QSFPDD-ZR-400G Transceiver

What Is 400G Open ROADM?

Open ROADM is a 400G pluggable solution that establishes interoperability standards for Reconfigurable Optical Add/Drop Multiplexers (ROADM), responsible for managing and routing data traffic over high-capacity fiber-optic lines. Initially developed in response to the surge in wireless network traffic from 2007 to 2015, Open ROADM consists of key components including ROADM switches, transponders, and pluggable optics. These components are controllable via an open standards-based API accessed through an SDN Controller using the NETCONF protocol.

Launched in 2016, the primary objective of the Open ROADM initiative was to bring together multiple vendors and network operators to develop scalable, cost-effective, and flexible network design approaches. By fostering collaboration and standardization, Open ROADM aimed to meet the evolving demands of network infrastructure, offering adaptable and efficient solutions.

• Open ROADM fosters collaboration among various vendors and operators to agree on network design strategies, ensuring flexibility alongside scalability and cost-effectiveness in network development.

• The multi-source agreement (MSA) driving Open ROADM aims to transition from closed ROADM optical transport networks to disaggregated open transport networks. This transition enables centralized software control while enhancing customization and efficiency in network design and operation.

• Open ROADM prioritizes functional disaggregation over hardware disaggregation, recognizing the complexity associated with common shelves. This emphasis on simplicity, particularly in lower-performance metro systems, streamlines network management and optimization.

• Open ROADM efficiently manages 100-400GbE and 100-400G OTN client traffic within a typical deployment range of 500km, making it ideal for various network configurations, especially in metropolitan areas.

Figure 2 : FS DWDM-400CFP2-DCO Transceiver

What Is 400G ZR+?

The 400G ZR+ series offers a range of coherent pluggable solutions with line capacities reaching up to 400 Gb/s, surpassing the 120km limit of the 400ZR specification. OpenZR+ maintains the classic Ethernet-only host interface of 400ZR while enhancing features like extended point-to-point reach, reaching approximately 500km, and supporting OTN Ethernet.

• The recent MSA guarantees interoperability for line rates ranging from 100G to 400G across different distances like regional, metro, and long-haul routes. This is enabled by utilizing OpenFEC forward error correction and adhering to optical line specifications between 100G and 400G.

• The ZR+ pluggable solutions offer extensive coverage and can be seamlessly deployed across a range of optical transport equipment, including routers, switches, and other devices, ensuring versatile compatibility throughout various components of optical networks.

Figure 3 : FS QDD-ZRP-400G-HT Transceiver

Differences in 400G ZR, Open ROADM, and ZR+

Target Application

400ZR and OpenZR+ were designed to satisfy the growing volume requirements of DCI and cloud operators using 100GbE/400GbE client interfaces, while OpenROADM provides a good alternative for carriers that require transporting OTN client signals (OTU4).

In other words, the 400ZR efforts concentrate on one modulation type and line rate (400G) for metro point-to-point applications. On the other hand, the OpenZR+ and Open ROADM groups concentrate on high-efficiency optical specifications capable of adjustable 100G-400G line rates and lengthier optical reaches.

400G Reach: Deployment Paradigm

400ZR modules support high-capacity data transport over DCI links of up to 80 to 120km. On the other hand, OpenZR+ and OpenROADM, under perfect network presumption, can transmit the network for up to 480 km in 400G mode.

Power Targets

The power consumption targets of these coherent pluggables also vary. For instance, the 400zr has a target power consumption of 15W, while Open ROADM and ZR+ have power consumption targets of not more than 25W.

Applications for 400G ZR, Open ROADM and ZR+

Each of these coherent pluggable solutions finds use cases in various settings. Below is a quick summary of the three data transfer standards and their major applications.

• 400G ZR: frequently used for point-to-point DCI (up to 80km), simplifying the task of interconnecting data centers.

• Open ROADM:This architecture can be deployed using different vendors, provided they exist in the same network. It gives the option to use transponders from various vendors at the end of each circuit.

• ZR+:It provides a comprehensive, open, and flexible coherent solution in a relatively smaller form factor pluggable module. This standard addresses hyperscale data center applications for high-intensive edge and regional interconnects.

A Look into the Future

As digital transformation takes shape across industries, there's an increasing demand for scalable solutions and architectures for transmitting and accessing data. The industry is also moving towards real-world deployments of 400G networks, and the three coherent pluggable solutions above are seeing wider adoption.

In the continuous innovation of the global optical network field, FS is committed to providing efficient and reliable solutions to meet the changing needs of customers. 400ZR and the OpenZR+ specifications were developed to meet the network demands of DCI and cloud operators using 100 and 400GbE interfaces. At the same time, our open ROADM and ZR+ series also provide greater advantages for data center operators. By choosing FS's solutions, you will get excellent performance and reliability, helping your network reach new heights.