At present, the IO modules of SFP28/SFP56 and QSFP28/QSFP56 are mainly used to connect switches and switches and servers in the mainstream cabinets in the market. In the age of 56Gbps rate, in order to pursue higher port density, people have further developed the QSFP-DD IO module to achieve 400G port capacity. With the doubling of the signal rate, the port capacity of the QSFP DD module has been doubled to 800G, which is called OSFP112. It is packaged with eight high-speed channels, and the transmission rate of a single channel can reach 112G PAM4. The total transmission rate of the whole package is up to 800G. Backward compatible WITH OSFP56, compared with the same time to double the speed, meet the IEEE 802.3CK association standard; As a result, link loss will increase sharply and the transmission distance of passive copper CABLE IO module will be further shortened. Based on realistic physical constraints, IEEE 802.3CK team, which formulated 112G specification, reduced the maximum length of copper cable link to 2 meters on the basis of 56G copper cable IO with a maximum speed of 3 meters.
QSFP-DD X 2 port 1.6Tbps test board
QQSFP -DD 800G comes up against the wind
Data center capabilities are determined by servers, switches, and connectivity factors that balance each other and push each other toward faster, lower-cost growth. Switching technology has been the main driving force for many years. As OFC2021 comes to an end recently, mainstream optical communication manufacturers such as Intel, Finisar, Xechuang, Opticexpress and New Yisheng have all displayed 800G series optical modules. At the same time, overseas optical chip companies showed high-end chip products for 800G, and the traditional scheme may still have a place in the 800G era. We think 800G optical module technology route is more and more clear, 800GDR8 and 2*FR4 have the most mainstream potential; As OFC2021 mainstream optical module and optical chip companies have launched new products one after another, the time node and mainstream technology route of 800G upgrade have been defined. The rate of data center optical module industry continues to iterate, and the long-term growth attribute has been determined. We believe that in the era of digitalization and intelligence, the continuous explosion of data center traffic has brought the demand for continuous iteration of optical modules. The clear technology route of 800G indicates that 400G will be large-scale.
When the 25Gbps signal rate is upgraded to the current 56Gbps signal rate, due to the introduction of PAM4 (Pulse Amplitude Modulation) signal system (IEEE 802.3BS group), The fundamental frequency point of the signal transmitted on the Serdes Ethernet link only moves up from 12.89ghz to 13.28ghz, and the signal fundamental frequency point does not change much. Systems that can support good transmission of 25Gbps signals can be upgraded to 56Gbps signal rates with slight optimization. Upgrading from 56Gbps signal rate to 112Gbps signal rate is not so easy. The PAM4 signal system introduced when the 56Gbps rate standard was developed will most likely be reused at 112Gbps rates. This changes the fundamental frequency point of 112Gbps Ethernet signal to 26.56ghz, which is twice that of 56Gbps signal rate. In the generation of 112Gbps rate, the cable technology requirements will face a more demanding test. At present, 400Gbps high-speed cable is connected to the product. Early mature brands are mainly foreign brands, such as TE, LEONI, MOLEX, Amphenol, etc. Domestic brands have also started to overtake in recent years. From the manufacturing process, equipment and materials, we have made many innovations. At present, there are domestic enterprises that manufacture 800G copper cable, but we have not collected much. Shenzhen Hongteda, Dongguan Zhongyou Electronics, Dongguan Jinxinuo, Shenzhen Simic Communication, etc., but the existing technical difficulty is mainly in the bare wire part. At present, it is relatively difficult to solve the high frequency electrical performance parameters and the softness requirements of cable wiring at the same time. DAC copper cable will face a period of rapid development. There are only a handful of local wire manufacturers.
The market is changing fast, and it will evolve even faster in the future. The good news is that significant and promising progress has been made, from standards bodies to the industry, to enable data centers to move to 400GB and 800GB. But removing technological barriers is only half the challenge. The other half is timing. Once misjudgment occurs, the cost will be higher. The mainstream of the existing domestic data center is 100G. Among the deployed 100G data centers, 25% are copper, 50% are multi-mode fiber, and 25% are single-module fiber. These provisional numbers are not exact, but the growing demand for bandwidth, capacity, and lower latency is driving the migration to faster network speeds. So every year, the adaptability and viability of large-scale cloud data centers is a test. Currently, 100GB is flooding the market, with 400GB expected next year. Despite this, data flow is still continuing to increase, the pressure on data centers will continue to increase, following 400G, QSFP-DD 800G has come.
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Post time: Aug-16-2022
