SX6018 to an Connect-IB MCB191A gives me only 40Gbps, not 56Gbps

We’ve been running an SX6018 for a couple of years, but with QDR adapters in the clients. Now, I’m looking at moving clients up to 56Gbps to better take advantage of the switch, so I got an Connect-IB single-port 56Gbps card (MCB191A), and connected it by a 2-meter direct attach copper cable (MCP170L-F002). Things come up and work as expected, but, the port on the switch only runs at 40Gbps. The port configuration in the web interface gives me only options up to 10Gbps per link (QDR and FDR10), no FDR 14Gbps per link options.

What am I missing here? Client is running Centos 7.4, mlx5 driver, no particular configuration of the adapter done on the client side. Switch is running MLNX-OS 3.4.0012 (which I should probably upgrade, but I need to renew our support contract for that, I think, and we haven’t gotten around to it).

Hi Joakim,

it’s the same ASIC but it’s restricted by software and fw. we can’t bypass this.

also the price is differnet between the FDR10 and FDR modules

Hi Joakim,

Can you provide the part number of the switch?

output of “show inventory” is fine.

or via the web

System → Modules


System → Inventory

I suspect the part number is SX6018T which means “SwitchX®-2 based 18-port QSFP FDR10 1U managed InfiniBand switch system”

Part number indeed starts with , so it seems you’re right. Is this actually a completely different switch, or is the 56Gbps full FDR speed a software option?