How to enable DCQCN on ConnectX-3 Pro

Hello, everyone.

In the community, I found the method to set the DCQCN parameters on ConnectX-4.

It writes “adjust the parameters under the path /sys/kernel/debug/kernel/mlx5/”.

However, the method could not be applied to ConnectX-3 Pro. And the path “/sys/class/net/device name/ecn” does not exist.

So how can I enable DCQCN on ConnectX-3 Pro?



Please note that ECN/DCQCN is not supported on ConnectX-3.

We do support RoCE with PFC in ConnectX-3 Pro, you can refer to the following guides:

HowTo Configure RoCE v2 for ConnectX-3 Pro using Mellanox SwitchX Switches

HowTo Run RoCE over L2 Enabled with PFC

Recommended Network Configuration Examples for RoCE Deployment



Hi, Samer

Thank you for your help. I saw that the DCQCN paper (Congestion Control for Large-Scale RDMA Deployments) said ConnectX-3 implemented DCQCN in firmware. So I wonder how to enable it.

One more question, can I configure the DCQCN on the 100Gbps ConnectX-5 EN card like ConnectX-4? Actually, I could not find relevant documents for ConnectX-5 EN in the community.

Thank you.

Hi ,

Regarding ConnectX-5 it is the same as ConnectX-4:

HowTo Configure DCQCN (ECN) Parameters for Windows Driver (WinOF-2)

This post illustrates how to set the DCQCN (ECN) parameters for WinOF-2 driver (ConnectX-4 and ConnectX-5 adapter cards).

HowTo Configure DCQCN (RoCE CC) values for ConnectX-4 (Linux)

DCQCN Parameters

Regarding ConnectX-3 , DCQCN was not implemented in the firmware.

We recommend using the tested and verified solution RoCE with PFC for ConnectX-3.



Thanks, very helpful.