Which cables for a pair of MCX353A-FCBT

Hi all, I have a pair of Mellanox MCX353A-FCBT coming my way.

I want to setup a point to point (no switch) 40Gbe link between a workstation and server.

I was also thinking about experimenting with the 56Gb Infiniband links and NFS + RDMA.

I was digging through documentation and came across this: https://www.mellanox.com/related-docs/prod_cables/PB_MC22061xx-00x_MC22071xx-0xx_MC22101xx-00x_MCP170L-F0xx_MCP1700-B0xxx_56Gbps_QSFP+_DAC.pdf

I am kinda confused about the description column.

Do some cables support VPI and Infiniband, and others support Ethernet only?

Or does a 56Gb card support all of the above?

For example:

MC2210126-005 Mellanox® passive copper cable, ETH 40GbE, 40Gb/s, QSFP, 5m

If I buy this and setup 40GbE can I not do infiniband with the same cable?

MC2207126-004 Mellanox® passive copper cable, VPI, up to 56 Gb/s, QSFP, 4m

If I buy this can I do ethernet via VPI but not infiniband?

MC2206125-007 Mellanox® passive copper cable, IB QDR, 40 Gb/s, QSFP, 7m

If I buy this am I relegated to only Infiniband?

I guess the real question for me is… do the 56G cables work with 40GbE. I would assume yes, but because I see this in the Mellanox PDF:

MC2210126-005 Mellanox® passive copper cable, ETH 40GbE, 40Gb/s, QSFP, 5m

MC2207126-004 Mellanox® passive copper cable, VPI, up to 56 Gb/s, QSFP, 4m

MC2206125-007 Mellanox® passive copper cable, IB QDR, 40 Gb/s, QSFP, 7m

It kinda seems like the MC2206125 is IB specific, the MC2207126 is VPI specific, and the MC2210126 is Ethernet specific.

I would guess the 56G cable is backwards compatible though.

Hi Ian,

Regarding the questions , please see below:

MC2210126-005 Mellanox® passive copper cable, ETH 40GbE, 40Gb/s, QSFP, 5m

If I buy this and setup 40GbE can I not do infiniband with the same cable?

Answer - Only Ethernet

MC2207126-004 Mellanox® passive copper cable, VPI, up to 56 Gb/s, QSFP, 4m

If I buy this can I do ethernet via VPI but not infiniband?

Answer - Ethernet and IB

MC2206125-007 Mellanox® passive copper cable, IB QDR, 40 Gb/s, QSFP, 7m

If I buy this am I relegated to only Infiniband?

Answer - Infiniband Only

Full list of supported cables

https://www.mellanox.com/products/interconnect/cables-configurator.php

In addition for ConnectX-3 VPI adapter please refer to the supported cables in the release notes

http://www.mellanox.com/pdf/firmware/ConnectX3-FW-2_42_5000-release_notes.pdf

Regarding MC2207126-004 it’s backward compatible.

For further questions, you can refer to our Sales department

Sales@mellanox.com

Thanks,

Samer

@Samer what about MC220731V-010?

Does that support IB and Ethernet?

Yes it’s VPI FDR, refer to the table

https://www.mellanox.com/products/interconnect/cables-configurator.php