Scale to 800G & 1.6T Interconnects for AI & HPC Clusters

As AI and HPC clusters move toward 800G and 1.6T networking, the right interconnect strategy is critical.

Our latest solutions based on NVIDIA ConnectX-8 adapters and NVIDIA Quantum‑3 switches enable flexible 800G and 1.6T architectures using OSFP and QSFP interfaces—supporting both ultra-low-latency copper for in-rack deployment and long-reach optical connectivity for large-scale clusters.

From 1.6T with dual 800G links to 800G breakout designs, these proven configurations help maximize bandwidth, simplify cabling, and future-proof your AI infrastructure.

ConnectX-8 delivers ultra-high-speed networking and higher throughput for modern AI and HPC infrastructure.

In this article, we’ll walk through practical connectivity solutions for CX-8 in different scenarios.

C8180 - One OSFP Cage(800G XDR or 2 x 400GbE)

The C8180 adapter provides one OSFP cage and supports:

800G XDR (single-port mode)

2 × 400GbE (breakout mode)

Scenario 1: 

1600G using 2 x C8180 in XDR 800G Mode

In this architecture, NVIDIA Quantum-3 based XDR InfiniBand Switch, Q3400-RA, 144 XDR Ports over 72 OSFP Cages, operates at 2x XDR800G. Each C8180 connects using one 800G link.

Two C8180 adapters together deliver 1.6T aggregate bandwidth.

Optical Solution

Use a twin-port 2x XDR800 OSFP module on the switch side

Each port connects to a single-port XDR800 OSFP module on C8180

Two single mode MPO-12/APC fibers are used for interconnection

This solution supports longer reach and is ideal for large-scale cluster deployment.

Copper Solution

For rack-level deployment:

1.6T OSFP to 2 × OSFP RHS DAC (≤1m)

1.6T OSFP to 2 × OSFP RHS AEC (≤3m)

This is suitable for Top-of-Rack GPU servers with minimal insertion loss requirements.

Scenario 2: 

1600G using 4 × C8180 in NDR 400G Mode

Using four C8180 adapters with Quantum-3 based XDR InfiniBand Switch (Q3400-RA) to hit 1.6T aggregate bandwidth.

Optical Solution

Use a twin-port 2 × XDR800 OSFP module on the switch side

Each port connects to a single-port NDR400 OSFP module on C8180

Two single mode fiber splitters are used for interconnection

Copper Solution

1.6T OSFP to 4 × OSFP RHS DAC (≤1m)

1.6T OSFP to 4 × OSFP RHS AEC (≤3m)

Scenario 3: 

800G using one C8180 in 2x400G Mode

The SN5400 with 64 ports of 400GbE over 36 OSFP, operates at 800GbE. C8180 connects using one 800G link.

One C8180 adapter delivers 800G bandwidth.

Optical Solution

Use a twin-port 2 × 400G OSFP module on the switch side

Each port connects to a twin-port 2 x 400G OSFP module on C8180

Two Single mode MPO-12/APC fibers are used for interconnection

Copper Solution

800G OSFP to OSFP RHS DAC (≤2m)

800G OSFP to OSFP RHS AEC (≤7m)

C8240 - Two QSFP Cages(2 x 400G)

The C8240 adapter provides two QSFP cages and each cage support 400Gbps. Two cages together deliver 800G aggregate bandwidth. 

Scenario: 800G using one C8240 in 2 x 400GbE or 2 x NDR 400G Mode

Optical Solution

Use a twin-port 2 × 400G OSFP module on the switch side

Each port connects to a single-port 400G QSFP module on C8240

Two single mode MPO-12/APC fibers are used for interconnection

Copper Solution

800G OSFP to 2 x QSFP RHS DAC (≤2m)

800G OSFP to 2 x QSFP RHS AEC (≤7m)

C8240 - Two QSFP Cages(400G or 2 x 200G)

The C8240 adapter provides two QSFP cages and supports:

400G(single-port mode)

2 × 200G (breakout mode)

Scenario 1: 800G using 2 x C8220 in 400GbE or NDR 400G Mode

Optical Solution

Use a twin-port 2 × 400G OSFP module on the switch side

Each port connects to a single-port 400G QSFP module on C8220

Two single mode MPO-12/APC fibers are used for interconnection

Copper Solution

800G OSFP to 2 x QSFP RHS DAC (≤2m)

800G OSFP to 2 x QSFP RHS AEC (≤7m)

Scenario 2: 

800G using 2 x C8220 in 2 x 200GbE or 2 x HDR 200G Mode

Optical Solution

Use a twin-port 2 × 400G OSFP module on the switch side

Each port connects to a single-port 400G QSFP module on C8220

Two single mode fiber splitters are used for interconnection

Copper Solution

800G OSFP to 4 x QSFP RHS DAC (≤2m)

800G OSFP to 4 x QSFP RHS AEC (≤7m)

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