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What Are the Advantages of the QSFP-DD Package?

Apr. 15, 2022

QSFP-DD is highly sought after by suppliers as the smallest size package for 400G optics, offering high port density and backward compatibility with QSFP+/QSFP28 packages. Today, many suppliers have launched 400G QSFP-DD products, such as 400G QSFP-DD optical modules, 400G QSFP-DD DAC/AOC, etc. So how much do you know about QSFP-DD packages? This article will take you through a fresh look at the QSFP-DD package and how it differs from the QSFP+/QSFP28/QSFP56 and OSFP/CFP8/COBO packages.


QSFP-DD package overview

The QSFP-DD (also known as QSFP56-DD), or dual-density quad-channel small form-factor pluggable package, is a new package of high-speed pluggable modules that comply with IEEE802.3bs and QSFP-DD MSA standards. The package has an 8-channel electrical interface with data rates of up to 25Gb/s per channel for 200G network transmission via NRZ modulation technology and up to 50Gb/s per channel for 400G network transmission via PAM4 modulation technology, making it suitable for high-performance computing data centers and cloud networks.

400GBASE-QSFP-DD-SR8-100m Optical Transceiver Module

 400GBASE-QSFP-DD-SR8-100m Optical Transceiver Module

QSFP-DD advantages are demonstrated by the following.

Backward compatibility with QSFP packages such as QSFP+/QSFP28/QSFP56.

The use of 2 x 1 stacked integrated cages and connectors to support single and double-height cage connector systems.

Using SMT connectors and 1xN cages, the cage design and optimization of the optical module housing enables a minimum of 12 watts of thermal capacity per module. The higher thermal capacity reduces the optical module's requirement for heat dissipation features, thus reducing some unnecessary costs.


The QSFP-DD was designed with user flexibility in mind, using an ASIC design that supports multiple interface rates and is backward compatible (QSFP+/QSFP28 compatible), thus reducing port costs and equipment deployment costs.

In summary, the QSFP-DD is a high-speed, small, pluggable, and low-power package that will become one of the mainstream packages for 400G.


400GBASE-QSFP-DD-SR8-100m Optical Transceiver Module

400GBASE-QSFP-DD-SR8-100m Optical Transceiver Module

Differences between QSFP-DD and QSFP+/QSFP28/QSFP56

Although the QSFP-DD and QSFP+/QSFP28/QSFP56 are both QSFP packages and the same size, there are still some differences between them, so what exactly is the difference between them?


In terms of structure, there are slight differences between the QSFP-DD and QSFP+/QSFP28/QSFP56 in terms of the depth of the mechanical interfaces on the motherboard, and the number of channels on the electrical interfaces, and the number of integrated circuits. The details are as follows.


Depth of mechanical interfaces on the motherboard - When designing the QSFP-DD, the mechanical interfaces on the motherboard are slightly deeper than those of the QSFP+/QSFP28/QSFP56 in order to allow the QSFP-DD to have the same port density as the QSFP+/QSFP28/QSFP56 and to accommodate an extra row of contacts.

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A number of channels of electrical interfaces - As can be seen above, the QSFP-DD package comes with 8 channels of electrical interfaces, doubling the number of channels of electrical interfaces compared to the QSFP+/QSFP28/QSFP56 package with 4 channels of electrical interfaces, thanks to the extra row of contacts on the QSFP-DD package.


The number of integrated circuits - Although the QSFP-DD is the same size as the QSFP+/QSFP28/QSFP56, the QSFP-DD doubles the number of integrated circuits (i.e. ASICs) and density compared to the 4-channel electrical interface QSFP+/QSFP28/QSFP56 due to its 8-channel electrical interface.


Bandwidth & Applications

QSFP-DD has a maximum bandwidth of 400Gbps, while QSFP+/QSFP28/QSFP56 only has a maximum bandwidth of 40Gbps/100Gbps/200Gbps respectively, making QSFP-DD much higher than QSFP+/QSFP28/QSFP56. 400G optical modules and 400G high-speed cables (i.e. DACs and AOCs) for 400G data center interconnection to solve the problem of high-speed migration of massive data between data centers, while QSFP+/QSFP28/QSFP56 are used for 40G/100G/200G optical modules and high-speed cables respectively for 40G/100G/200G network interconnections.

Guanglian's cloud data center optical transceivers solution, including 10G/25G/40G/100G/200G/400G, all our data center optical transceiver uses our mature and experienced high-speed COB manufacturing technology to provide our customers a cost-effective solution with highly reliable, excellent consistency on optical performances. Guanglian’s strong R&D department will continue to provide better solutions for the industry. If you want to know more information about the best optical transceiver, welcome to contact us today or request a quote.  

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