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FS 400G QSFP DD: Complete Guide and Solutions

Updated on Jun 23, 2022 by
6.4k

400G

Recent years have seen the evolution towards the Internet of Things (IoT) and the explosion of AI, cloud computing and 5G, increasing pressure on data centers to ramp up network capacity to 400G. The demand for 400G Data Center Interconnects (DCIs) has prompted cloud service providers and data centers to explore innovative solutions for both intra-Data Center Interconnect and inter-Data Center Interconnect. 400G QSFP-DD is becoming one of the most popular cutting-edge 400G DCI solutions.

So, why choose QSFP-DD transceivers and cables over other form factors like OSFP, CFP8, or even COBO? And how to utilize it for 400G DCI applications. Read more to find out.

Basic Introduction of FS QSFP-DD 400G Form Factor

FS QSFP-DD (also called QSFP56-DD) stands for Quad Small Form Factor Pluggable Double Density. It has double interfaces than which QSFP28 has. QSFP-DD is IEEE802.3bs and MSA standard compliant. With high-level PAM4 modulation technology, it can deliver a 400G (8x 50G or 4x 100G) signal with minimized power consumption, which makes it qualified to create a cost-effective way to scale to 400G for data centers at the same time reducing per port hardware costs.

400G QSFP-DD DR4 Module

Figure 1: 400G QSFP-DD DR4 Module

How Does 400G QSFP-DD Outperform Other Form Factors?

Compared to the other 400G form factors like OSFP, CFP8, and COBO, QSFP-DD is of great benefits when applied for data center interconnects, including:

  • Being backward compatible with QSFP+, QSFP28, and QSFP56 makes it much easier to upgrade to 400G networks.

  • Supported by PAM4 modulation, QSFP-DD is a more cost-effective solution for 400G data center connectivity with ultra-low power consumption.

  • 400G QSFP-DD provides more flexibility and scalability since it has more lanes (8 or 4 lanes) than other form factors.

For more detailed information about the differences between these form factors, please check this article for reference: Differences Between QSFP-DD and QSFP+ / QSFP28 / QSFP56 / OSFP / CFP8 / COBO.

FS 400G QSFP-DD Data Center Connectivity Solutions

The network architecture of the Next-Generation 400G Data Center is generally divided into three layers, namely, Spine Core, Edge Core, and ToR (Top of Rack). There are various 400G QSFP-DD equipment for data center interconnects of different transmission distances.

Architecture of 400G DCI

Figure 2: Architecture of 400G DCI

Transmission Distance < 5m

The transmission distance between ToR access switches and server NICs is generally less than 5m. In this case, FS 400G QSFP-DD DAC cables would be a better option. It primarily enables high-bandwidth 400G links and provides a QSFP-DD-to-QSFP-DD copper direct-attach solution when QSFP-DD modules are adopted in 400G DCI. They are suitable for very short links and offer a cost-effective way to establish a 400-Gigabit link between QSFP-400G ports of switches/routers within racks and across adjacent racks.

Transmission Distance < 100m

For the transmission between ToR access switches and Edge switches, which is generally less than 100m, 400G QSFP-DD AOC with 8x 50G PAM4 modulation technology is more often used with its advantages of lower weight, longer transmission distance, and easier installation and maintenance.

Transmission Distance < 2km

The transmission distance between Edge switches and Spine Core switches is generally less than 2km, for which FS 400G QSFP-DD FR4 optical transceivers featuring low-power, high-density, and high-speed would be a great option.

Transmission Distance < 100km

The transmission between Spine Core and Core Router belongs to DCI Metro Interconnect where the transmission distance is generally less than 100km. FS 400G QSFP-DD LR8 and QSFP-DD ZR transceivers can achieve high-speed transmission with PAM4 technology for the interconnect between the Spine Core and Core Router.

FS 400G QSFP-DD Transceivers and Cables Recommendation for DCI

400G QSFP-DD transceivers are used more and more widely in data center interconnection. To better meet users' application requirements for different rates and optical modules, FS provides a full range of 400G QSFP-DD optical modules with 400G QSFP-DD DAC/AOC cables and DAC/AOC breakout cables, supporting different transmission rates and transmission distances. FS 400G QSFP-DD series products have powerful diagnostic capabilities, digital optical monitoring capabilities, low insertion loss, and ultra-low crosstalk performance. After rigorous equipment testing, they deliver exceptional performance, quality, and reliability.

FS 400G QSFP-DD Transceivers

Modules Max. Data Rate Form Factor Wavelength Max. Distance
400G QSFP-DD SR8 400Gbps QSFP-DD 850nm 100m
400G QSFP-DD DR4 425Gbps QSFP-DD 1310nm 500m
400G QSFP-DD XDR4 400Gbps QSFP-DD 1310nm 2km
400G QSFP-DD LR4 400Gbps QSFP-DD 1271nm,1291nm,1311nm,1331nm 10km
400G QSFP-DD LR 400Gbps QSFP-DD 1310nm 10km
400G QSFP-DD ER8 425Gbps QSFP-DD 1310nm 40km

FS 400G QSFP-DD DAC/AOC Cables

Modules Max. Data Rate Form Factor 1 Form Factor 2 Cable Length
0.5m (2ft) 400G QSFP-DD DAC 400Gbps QSFP-DD QSFP-DD 0.5m (2ft)
1m (3ft) 400G QSFP-DD DAC 400Gbps QSFP-DD QSFP-DD 1m (3ft)
1.5m (5ft) 400G QSFP-DD DAC 400Gbps QSFP-DD QSFP-DD 1.5m (5ft)
2m (7ft) 400G QSFP-DD DAC 400Gbps QSFP-DD QSFP-DD 2m (7ft)
2.5m (8ft) 400G QSFP-DD DAC 400Gbps QSFP-DD QSFP-DD 2.5m (8ft)
3m (10ft) 400G QSFP-DD DAC 400Gbps QSFP-DD QSFP-DD 3m (10ft)
1m (3ft) 400G QSFP-DD AOC 400Gbps QSFP-DD QSFP-DD 1m (3ft)

FS 400G QSFP-DD DAC/AOC Breakout Cables

Modules Max. Data Rate Form Factor 1 Form Factor 2 Cable Length
400G QSFP-DD to 2x200G QSFP56 DAC 400Gbps QSFP-DD QSFP56 0.5m (2ft), 1m (3ft), 1.5m (5ft), 2m (7ft), 2.5m (8ft)
400G QSFP-DD to 4x100G QSFP56 DAC 400Gbps QSFP-DD QSFP56 0.5m (2ft), 1m (3ft), 1.5m (5ft), 2m (7ft), 2.5m (8ft)
400G QSFP-DD to 8x50G SFP56 DAC 400Gbps QSFP-DD SFP56 0.5m (2ft), 1m (3ft), 1.5m (5ft), 2m (7ft), 2.5m (8ft), 3m (10ft)
400G QSFP-DD to 4 x100G QSFP28 DAC 400Gbps QSFP-DD QSFP28 1m (3ft), 3m(10ft), 5m(16ft)
400G OSFP to 2 x 200G QSFP56 AOC 425Gbps(8x53.125Gb/s) OSFP QSFP56 3m (10ft), 5m (16ft), 10m (33ft), 15m (49ft), 20m (66ft), 30m (98ft)
400G QSFP-DD to 4 x 100G QSFP28 AOC 400Gbps QSFP-DD QSFP28 1m (3ft), 2m (7ft), 3m (10ft), 5m (16ft), 7m (23ft), 10m (33ft), 15m (49ft), 20m (66ft)
400G QSFP-DD to 4x100G QSFP56 AOC 400Gbps QSFP-DD QSFP56 1m (3ft), 2m (7ft), 3m (10ft), 5m (16ft), 7m (23ft), 10m (33ft), 15m (49ft), 25m (82ft), 30m (98ft), 50m (164ft)
400G QSFP-DD to 2x200G QSFP56 AOC 425Gbps(8x53.125Gb/s) QSFP-DD QSFP56 1m (3ft), 2m (7ft), 3m (10ft), 5m (16ft), 7m (23ft), 10m (33ft), 15m (49ft), 20m (66ft), 25m (82ft), 30m (98ft)
400G QSFP-DD to 8x50G SFP56 AOC 425Gbps (8x 53.125GGbps) QSFP-DD SFP56 1m (3ft), 2m (7ft), 3m (10ft), 5m (16ft), 7m (23ft), 10m (33ft), 15m (49ft), 20m (66ft), 25m (82ft), 30m (98ft), 50m (164ft), 70m (230ft)

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