Naddod 400G QSFP-DD SR4: Exclusive Design Empowering Data Center Interconnect

NADDOD Mark News Writer Feb 5, 2024

Entering the era of supercomputing, data centers are experiencing a leap in development. With the continuous evolution of technology, the rise of AI supercomputing is leading the wave of innovation in the digital realm. In this data-centric era, the demand for data centers goes beyond mere scalability; there is an urgent thirst for high-speed transmission. With transmission rates of 400G/800G, like a powerful digital trend, they are redefining the infrastructure of data centers.


In this article, NADDOD introduces a brand-new 400G product: the 400G QSFP-DD SR4 optical module. Let's explore how it is being utilized in today's data centers.



Existing 400G Networking Solutions

The high-speed network in a GPU cluster is primarily composed of high-speed network cards, optical connectors (optical modules and cables), and high-speed switches. Currently, servers equipped with H800 GPUs mainly adopt the NVIDIA CX7 400G network card, and there are various options for switches available in the market. These options include the 64400G QDD switch based on the BCM 25.6T Tomahawk4 (TH4) chip, the 64800G switch based on the BCM 51.2T chip, switches based on Cisco Nexus chips, and 400G/800G switches based on NVIDIA Spectrum chips. From a market perspective, the 400G QDD switch is currently the dominant choice. The diagram below illustrates the commonly used network architecture in a cluster:

400G spine leaf

It can be observed that the mainstream 400G switches in the market adopt 56GSerDes, while the CX7 network card uses 112G SerDes. To ensure network connectivity, it is necessary to consider this difference when selecting optical modules, ensuring compatibility and normal operation of the components. Please refer to the diagram below:


CX7 nic

To address this issue, the current approach is to use 400G QSFP-DD DR4 optical modules on the switch side, and 400G OSFP DR4 optical modules on the server side. The connection is illustrated in the diagram below:


400G OSFP DR4 link

Within a connection distance of up to 500m, the solution mentioned earlier is effective. However, if the connection distance is not more than 100m, opting for the DR4 solution might be wasteful. In such cases, a cost-effective option is to use the short-range 400G QSFP-DD SR4 with low-cost 850nm VSCEL lasers. This option is much cheaper than DR4 and can meet the transmission distance requirement of 100m.


The 400G QSFP-DD SR4 can be plugged into the port of the 400G QSFP-DD 8×50G PAM4, enabling interconnectivity between the 400G QSFP-DD SR4 and the 400G OSFP SR4 network card (4×100G PAM4). This is illustrated in the diagram below:


QSFP-DD 400G SR4 Interconnection


The newly released NADDOD 400G QSFP-DD SR4 features an 8×50G PAM4 modulation on the electrical interface and a 4×100G PAM4 modulation on the optical interface. Compared to the 400G QSFP-DD SR8, it reduces the number of lasers by 4, resulting in lower power consumption and cost, with power consumption below 8W. It utilizes an MPO12 optical interface and is compatible with OM3 multimode fiber for up to 60m transmission and OM4 multimode fiber for up to 100m transmission.


The introduction of NADDOD 400G QSFP-DD SR4 fills the gap in short-distance 400G data center interconnect solutions, providing you with a more comprehensive selection for your data center.


If you are interested in purchasing NADDOD 400G QSFP-DD SR4 optical module or have further inquiries, please feel free to contact Naddod with your requirements. We will respond promptly and ensure fast delivery!