What is 400ZR? A Beginner Guide

The fast growth of the connected society in recent years has increased the demand for data traffic in enterprise data centers and metro networks. It has directly contributed to the continuous expansion of data center construction and total capacity. As a result, data center architectures are becoming increasingly decentralized.

Performance-critical applications such as commercial services, artificial intelligence (AI), and big data need low-latency, high-bandwidth east-west designs to support massive machine-to-machine input/output (I/O) generated between servers. All of these considerations are driving the development of the 400ZR.

In this post, we will explore what the 400ZR is, its application situations, and popular 400ZR optical transceivers.

What is 400ZR? (Definition)

400ZR is an interoperable networking Implementation Agreement (IA) issued by the OIF in March 2020. It primarily aims at short-reach, single-span fiber optic networks for Data Center Interconnect (DCI).

The 400ZR standard will transmit 400Gb Ethernet (GE) payloads across DCI lines up to 80km~120km long using dense wavelength division multiplexing (DWDM) and high-order modulation. The objective is to assure a low-cost, long-term deployment based on single-carrier 400G employing dual-polarized 16-state quadrature amplitude modulation (16 QAM) at 60 gigabits per second (Gbaud).

*400ZR reference diagram (source from https://www.oiforum.com)*

Learn more: What is Data Center Interconnect (DCI): Definition, Technology, Application

What is the 400ZR application?

400ZR is suitable for 400GE applications sited in data center Interconnects, which require 400Gbps Ethernet line-side speeds with a reach of up to 80km. Including the below application:

Hyperscale Data Centers Application

Hyperscale data centers owned by Google, Amazon, Twitter, Facebook, Baidu, Tencent, and Alibaba make up a big part of the demand for high-speed networking in data centers. To keep up with the exponential growth of cloud services, IoT devices, streaming video, and more, these Hyperscale data centers need to speed up connections. New 400ZR and DCI technologies help cloud and hyperscale data centers meet the growing need for network bandwidth.

Distributed Campuses and Metropolitan Areas Application

Many companies do not have the financial resources necessary to construct a hyperscale data center. This is especially true for campuses spread out throughout large areas and large cities, where managing several data centers has become the new standard due to the limited space available and the requirement for disaster recovery.

Distributed data centers need to communicate with one another to share data, distribute and balance workloads, provide backups, and scale up or scale down the data center’s capacity depending on the requirements. Using 400ZR technology will make it feasible to establish connections between data centers with high bandwidth.

Telecom Operator Application

Using the 400G ZR standard, telecom operators will have the ability to backhaul residential traffic. When running at a speed of 200 Gb/s with 64 Gbaud signalings and QPSK modulation, 400ZR could improve the range of high loss spans. By merging several 25 Gb/s streams, 400G ZR can provide mobile backhaul for 5G networks. The 400ZR helps to promote future applications and markets for 5G technology.

400ZR Transceiver Types introduction

400G OSFP and QSFP-DD transceivers are the two mainstream 400G transceiver form factors for 400ZR applications.

The 400G QSFP-DD (Quad Small Form-Factor Pluggable Double Density) transceiver is a new form factor that supports 400Gbps Ethernet and Optical Transport Network (OTN) applications. It is an enhanced version of QSFP+, QSFP28, and QSFP56 that provides double port density and increases power efficiency.

Unlike QSFP-DD, the 400G OSFP transceiver is an optical transceiver with OSFP (Octal Small Form-factor Pluggable) interface. 400G OSFP transceivers offer various advantages, such as a more comprehensive thermal operating range and support for higher power consumption.

FAQs about 400ZR

Below are some frequently asked questions about 400ZR.

Q: What are the differences between 400ZR, 400ZR+, and OpenZR+?

A: The main difference is the application scenarios. 400ZR is for 400GE Edge data center interconnect, while 400ZR+ is for a longer distance (≥ 120km). OpenZR+ is a multi-source agreement-based standard that arose from the need to combine the best of the 400ZR+ and Open ROADM standards, and it aims for long-distance, regional networks.

Q: What 400ZR optics modules are available?
A: 400G QSFP-DD and 400G OSFP transceiver are the two major 400G optics form factors for 400ZR applications.

Final Words

As one of the crucial next-generation Ethernet standards, 400ZR has the potential to revolutionize data center connectivity and beyond. Understanding its detailed requirement and application is essential for any 400G device or system vendor. We hope you found this guide helpful in your journey to understanding 400ZR. Remember to stay tuned for more industry-standard MSA articles!

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Reference:

400ZR MSA

Optical Networking, Optical Transceiver