Hardware
- Switch: MikroTik CRS326-24S+2Q+RM
- QSFP+ 40Gbe DAC cable: FS 3m (10ft) Generic Compatible 40G QSFP+ Passive Direct Attach Copper Cable
- Network card: Mellanox ConnectX-3 MCX353A-FCBT
- Connection is (Switch) <--- DAC ---> (Network card, PC with Ubuntu 20.04)
Software
- RouterOS for MikroTik CRS326-24S+2Q+RM: v6.47.2
- Network card firmware (latest available): 2.42.5000
Symptoms
- DAC cable gets recognized, but there is no link
What I tried in RouterOS to fix the problem
- Turned off auto negotiation
- Set the port to 40 Gbe manually on both ends (disabled auto negotiation and set the speed manually)
- Set the port to 10 Gbe manually on both ends (disabled auto negotiation and set the speed manually)
It works but only if I set it to 10 Gbe. In the Interface list I see only the first channel out of 4 is used when I transfer files, so I only hit max 10 Gbps.
Any ideas?