QSFP-DD package with high speed, small size, pluggable and other advantages becomes the 400G favor. 400G QSFP-DD optical module has become the next generation of data center network interconnection one of the most popular optical modules. With the standardization of 400G, major manufacturers and suppliers have developed different types of 400G QSFP-DD optical modules, such as the 400G QSFP-DD SR8 optical modules shipped by Kyushu Internet in large quantities. This document focuses on the types of 400G QSFP-DD optical modules and their connection schemes, so that you can better deploy the network.

QSFP-DD encapsulation Overview

QSFP-DD(Quad Small Form Factor Pluggable-Double Density) is a new type of module connector system that adopts a dual-density, four-channel compact hot-swappable optical module package. The packaged electrical interface has 8 channels with rates of up to 25Gb/s (NRZ modulation) or 50Gb/s (PAM4 modulation) per channel, aggregated to provide solutions up to 200Gb/s or 400Gb/s for HPC data centers and cloud networks.

QSFP-DD encapsulation advantages

1, the use of 8-channel electrical interface, with backward compatibility, can be compatible with QSFP+/QSFP28/QSFP56 QSFP package, reduce port costs and equipment deployment costs.

2, using 2×1 stacked integrated cage and connector. Due to industry demand, in addition to single-height cage connector systems, most pluggable packages eventually develop a double-height stacked cage connector system. The QSFP-DD MSA team chose to develop both single-height and double-height cage connector systems.

3, the use of SMT(Surface-Mount Technology) connectors and 1xN cages, cage design optimization and module shell optimization can achieve at least 12 watts of heat capacity per module, higher heat capacity reduces the module's requirements for heat dissipation function, thereby avoiding unnecessary costs.

400G QSFP-DD optical module categories

At present, the types of 400G QSFP-DD optical modules are 400G QSFP-DD SR8, 400G QSFP-DD DR4, 400G QSFP-DD FR4, 400G QSFP-DD LR4 and so on. See the following table:

Among them, "SR" refers to the transmission distance of 70 meters, 100 meters or 150 meters using multi-mode fiber, and 8% indicates that the module has eight fiber channels; "DR Refers to the transmission distance of 500 meters using single-mode fiber, and "4" means that the module has four fiber channels; “FR" refers to a transmission distance of 2 km using single-mode fiber;" "LR" refers to a transmission distance of 10 km using single-mode fiber.

Common connection scheme of the 400G QSFP-DD optical module

400G QSFP-DD SR8 optical module

As can be seen from the above, the 400G QSFP-DD SR8 optical module can achieve 40OG transmission through multi-mode fiber, and the maximum distance can reach 100 meters (OM4). Therefore, the 400G QSFP-DD SR8 optical module is more suitable for short-distance interconnection or multi-channel data communication.

400G interconnect

The 400G QSFP-DD SR8 optical modules at both ends can be connected through the MPO/MTP-16 optical fiber jumper to achieve 400G transmission.

Multichannel data communication

① The 400G QSFP-DD SR8 optical module can be connected to the peer 200G SR4 optical module through an MPO/ MTP-16 to 2 x MPO/MTP 8 optical fiber jumper.

② The 400G QSFP-DD SR8 optical module can be connected to the peer 50G SFP optical module through a 16-core MPO/MTP to 8*LC duplex branch optical fiber jumper.

400G QSFP-DD DR4 optical module

Since the transmission distance of the 400G QSFP-DD DR4 optical module can reach 500 meters, and it supports the interconnection with the 100G DR Optical module, the module is suitable for short distances of 400G and 100G Interconnect. The 400G QSFP-DD DR4 optical module can be connected to the peer 100G DR Optical module through the MPO-12 to 4*LC duplex branch optical fiber jumper.

400G QSFP-DD FR4 optical module

Because the 400G QSFP-DD FR4 optical module uses an uncooled EML laser with four CWDM wavelengths and a rate of up to 106.25Gbps on a single wave transmission based on PAM4 modulation, the module is suitable for 400G interconnects. Two 400G QSFP-DD FR4 optical modules can be interconnected through LC duplex fiber jumpers.

Question answering

Q: Can the 400G QSFP-DD optical module be inserted into the OSFP port?

A: No, because QSFP-DD and OSFP package structure, size, etc., are different, such as QSFP-DD using four-channel small double density, OSFP using eight-channel small pluggable, and QSFP package than QSFP-DD package size is larger, the two are not compatible. For more information about OSFP optical modules, visit the 400G OSFP Optical Module Types and Connection Solutions Overview. In addition, it should be noted that your network devices are packaged in QSFP-DD, so you must use QSFP-DD optical modules or QSFP-DD DAC or QSFP-DD AOC.

Q: 400G products in addition to the QSFP-DD optical module mentioned above, what else?

A: There are also 400G QSFP-DD DAC and AOC products.

Q: Can the 100G QSFP28 optical module be inserted into the port of QSFP-DD?

A: Yes, because the QSFP-DD package can be backward compatible, you can set the QSFP-DD port to 100G through configuration, and then insert the 100G QSFP28 optical module for transmission. In this case, the transmission rate of the link is 100G.

A part of C-light 400G/800G transceiver list