How many DGX Sparks can be interconnected using ConnectX?

Accelerated Computing DGX Spark / GB10 User Forum DGX Spark / GB10
1

NVIDIA announced that up to two DGX Sparks can be connected.
However, looking at the ConnectX ports on the DGX Spark, there are only two ports.
This seems to imply that more than two DGX Sparks can be connected.
Is it true that more than two DGX Sparks can be connected, but NVIDIA is blocking it? Or is the hardware specification such that only two DGX Sparks can be connected, as NVIDIA states?

2

Ethernet is the underlying protocol; clustering more than two Spark units is supported with compatible QSFP cables and Ethernet switches.

3

Do I need to use a QSFP switch to connect more than two? Can’t I just connect more than two DGX Sparks directly using QSFP cables?

4

Connecting Spark CX7 to a QSFP Ethernet switch is the same process as with any other QSFP-capable device. No Spark-specific adjustments are needed since it’s standard Ethernet.

The direct cabling method you desribed Direct-cabling CX7 ports between multiple nodes (a mesh or ring) can work for two nodes using a single cable.

But once you go beyond two nodes:

  • requires a switch to manage MAC address learning and traffic forwarding.

  • Point-to-point links between several nodes quickly form loops or routing complexity unless you manually set up static IPs, routing tables, or bridging.