The Next Trend in Data Centers: 200G VS 400G Optical Transceivers

With the rapid development of technologies such as mobile internet, cloud computing, and big data, the entire telecommunications industry has been demanding higher speeds, larger bandwidth, and lower latency from networks after the transition from 10G-40G-100G or 10G-25G-100G. There is an urgent need to upgrade networks to higher levels. The application of 200G and 400G Ethernet in data centers has attracted increasing attention, and the choice between 200G Ethernet and 400G Ethernet has become a hot topic in the industry.

 

Background of 200G and 400G Optical Transceivers

A 200G optical transceiver refers to an optical transceiver with a transmission rate of 200Gbps. There are two technological approaches for 200G optical transceivers. One approach is the cost-effective 8x25G NRZ modulation using QSFP-DD packaging. The other approach is the 4x50G (with a maximum of 4x56G) PAM4 modulation using QSFP56 packaging.

 

400G optical transceiver refers to an optical transceiver product with a transmission rate of up to 400Gbps. QSFP-DD is currently the preferred packaging method for 400G optical transceivers. It uses an 8-channel electrical interface, with each channel capable of reaching speeds of up to 50Gb/s (PAM4 modulation), providing a solution that aggregates up to 400Gb/s. The NVIDIA SN5400 64-port QSFP-DD 400GbE switch, when paired with QSFP-DD optical transceivers, can achieve aggregated bandwidth of up to 25.6Tb/s, thereby supporting the high-bandwidth requirements and continuous growth of data center traffic.

 

Differences Between 200G and 400G Optical Transceivers

200G optical transceivers and 400G optical transceivers support maximum transmission rates of 200G and 400G, respectively. The 400G optical transceiver clearly has a higher transmission speed and capacity than the 200G transceiver, allowing for a wider range of applications in the network communication industry.

 

1. Different Transmission Rates

The transmission rate of a 400G optical transceiver is twice that of a 200G optical transceiver. In other words, the maximum transmission rate of a 400G module is twice that of a 200G module

 

2. Different Packaging Types

200G optical transceivers are primarily available in two packaging types: QSFP-DD and QSFP56. The mainstream packaging type for 400G optical transceivers is currently QSFP-DD.

 

QSFP56 VS QSFP-DD Packaging

Form Factor	QSFP-DD	QSFP56	QSFP28	QSFP+
Backward Compatibility	QSFP+,OSFP28,QSFP56	QSFP+,QSFP28	QSFP+	N/A
Per Channel Data Rate	25G/50G	50G	25G	10G
Modulation Type Supported	NRZ & PAM4	PAM4	NRZ	NRZ
Lane Count	8	4	4	4

 

3. Different Costs

The cost of a 400G optical transceiver is higher than that of a 200G optical transceiver because it requires more optical components and a more complex manufacturing process.

 

Trends in the Development of 200G/400G Optical Transceivers

A foreseeable trend in the data center optical interconnect market is the gradual phasing out of low-speed optical transceivers in core networks and data centers. With the widespread adoption of spine-leaf network architecture, the demand for optical transceivers in data centers will shift from 25/100G to 50/200/400G. Compared to traditional three-tier architectures, the number of optical transceivers required per rack in a spine-leaf architecture will significantly increase.

 

Additionally, AI-generated content technologies like ChatGPT, relying on powerful AI models and massive data, have the potential to drive wider applications of artificial intelligence. Computing power, as one of the important pillars of AI-generated content technologies, is a core factor influencing the development and application of AI.

 

The computing power infrastructure has become a crucial resource that the industry urgently needs to invest in. In addition to the strong demand for computing hardware such as GPUs, the network side has also generated a greater need for higher bandwidth to match the growing traffic. As a result, the shipment proportion of high-speed rate switches is rapidly increasing, which will create a broader market space for high-speed optical transceivers.

 

QSFP-DD packaging is currently the most popular packaging type in the 400G Ethernet market. However, this does not mean that QSFP56 packaging type will be phased out. For data centers that do not have such high-speed rate requirements of 400G, deploying 200G QSFP56 packaged optical transceivers for 200G Ethernet is still an ideal solution. If considering an upgrade to 400G, deploying 200G QSFP-DD packaged optical transceivers would be a more cost-effective and efficient solution.

 

Industry Outlook Prediction

Currently, the application scope of 200G and 400G optical transceivers is continuously expanding, and the application field of 400G QSFP-DD optical transceivers will further expand. With the rapid development of the digital wave, manufacturers have been committed to improving the compatibility, stability, and reliability of 400G QSFP-DD, and it is expected to become the mainstream product in areas such as data center applications in the coming years.

 

Low-cost and low-power Direct Attach Cables (DAC) and Active Optical Cables (AOC) based on optical transceiver designs are also experiencing significant growth in short-distance high-speed interconnections. The optical transceiver market is evolving towards higher speeds, lower power consumption, and smaller form factors or sizes. In future developments, 400G optical transceivers are expected to become the leading technology in the field of optical communications, while 200G optical transceivers will continue to play an important role. Therefore, the optical transceiver market still presents significant opportunities.

 

NADDOD is a leading provider of comprehensive optical networking solutions, dedicated to building a connected world of digital intelligence through innovative computing and networking solutions. NADDOD continuously provides users with innovative, efficient, and reliable products, solutions, and services. It offers a full range of products including optical transceivers, high-speed DAC cables, and active optical cables (AOC) for data centers, high-performance computing, edge computing, artificial intelligence, and other application scenarios. It also provides DPU+GPU integrated solutions to significantly enhance customer business acceleration capabilities with low cost and outstanding performance.