Since 2019, 400G has become a hot topic in the optical communications industry. Several leading optical module manufacturers in the world have launched their own 400G optical modules and most of them have adopted QSFP-DD packages. As early as March 21, 2016, the QSFP-DD MSA team began to plan to develop the QSFP-DD high-speed interface, and experienced the resolution of a series of issues such as specification formulation. Finally, on September 18, 2018, the QSFP-DD MSA team released Version 4.0 of the QSFP-DD hardware specification and version 3.0 of the general management interface specification for 8/16-channel pluggable optical modules, so now the QSFP-DD MSA is relatively complete. Next, ETU-LINK will introduce to you what the QSFP-DD package is.

QSFP-DD is a dual-density four-channel small pluggable package. It is a high-speed pluggable module package defined by the QSFP-DD MSA group. It is the first choice for 400G optical module packages, enabling data centers to grow effectively and expand cloud capacity according to the needs..

The 400G QSFP-DD package uses 8-channel electrical interfaces, and each channel has a rate of up to 25Gb/s (NRZ modulation) or 50Gb/s (PAM4 modulation), providing up to 200Gb/s or 400Gb/s aggregation solutions. QSFP-DD can achieve up to 14.4Tb/s aggregate bandwidth in a single switch slot, and the bandwidth of QSFP-DD can be up to ten times that of QSFP+ or four times that of QSFP28.

QSFP-DD can not only achieve QSFP forward and backward compatibility, but also compatible with existing QSFP28 optical modules and AOC/DAC. The port density of QSFP-DD and QSFP+/QSFP28 systems are the same.

Compared with QSFP+/QSFP28, QSFP-DD only increases the length a little, and increases the bandwidth to 10 times/4 times of the latter while keeping the port density unchanged.

The above is the advantage of the QSFP-DD package, which has unparalleled advantages in the 400G data center interconnection scene. It is expected that the world's leading ultra-large-scale data center will soon deploy 400G, and QSFP-DD may become the mainstream package.