Noob with a new ConnectX-4 -- transceiver to 1GbE question

[schmookeeg]

Hi gang,

I am in the process of upgrading our 5 year old R330 Dell box to something two notches better -- an R740XD.

This new server comes with a pair of ConnectX-4 NICs on an OCP card. I use QSFP+ at home, but only point-to-point (thanks to STH forums, this was pretty painless! ) -- but I am new to SFP28 and OCP.

It's specifically a "Mellanox ConnectX-4 Lx Dual Port 25GbE DA/SFP rNDC"

Can someone check my assumptions?

This is getting racked into a shared colo cabinet, so will need some sort of 1G transceiver for the uplink. I assume something like this will work?

Generic 1000BASE-T RJ45 SFP Transceiver Module - FS.com

Check Generic Compatible copper RJ45 SFP transcevier module data sheet (1000BASE-T SFP connector, RJ45 interface, 100m) and price list!

www.fs.com

I note that FS does not offer a Mellanox-specific 1GbE transceiver, so I assume the generic is the correct play.

I have also read here that the MLNX cards are pretty tolerant about transceivers so I may be overthinking things.

I assume I don't need to care what sort of switch this is plugging into upstream? (going to Quadranet Los Angeles, although that is up for review as part of this swap too -- since I live in Alameda now )

This will be headed to a Citrix Hypervisor installation if it matters.

Appreciate any calling out of where the footguns may be hiding!

Cheers,

- Mike

 

[klui]

It should work. I have a system with dual-port CX4 Lx with a Juniper-compatible RJ45 SFP (Fluxlight EX-SFP-1GE-T). The BMC works over it as well.

 

[iZohanX]

This should work fine if I recall correctly.
About a year ago I was reading up on whether SFP28/SFP are backwards compatible. The conclusion is that you can plug SFP transceivers into SFP28 sockets (i.e NICs) but not the other way around, as an SFP28 cable/transceiver can't communicate with a regular SFP socket.
This is due to SFP28 sockets having the extra electrical traces as opposed to SFP sockets.

 

[i386]

I don't have a lot of experience with dell server, so it's probably a silly question; does this configuration come without any 1gbe ports on the mainboard?
Using a mellanox nic for 1gbe seems overkill to me

 

[klui]

Nah, the system only has a built-in iDRAC port. "Built-in" network ports are available in what looks like an OCP 2.0 LOM.

 

[schmookeeg]

I don't have a lot of experience with dell server, so it's probably a silly question; does this configuration come without any 1gbe ports on the mainboard?
Using a mellanox nic for 1gbe seems overkill to me

Haha, no doubt -- that was my thought as well -- but no, only the onboard iDRAC these days. My 13th gen dell had a pile of 1GBe ports

Have bought a 10GTek 10Gb transceiver, and an ipolex 1Gb. Will see how they play with my home network before I ship it off to be racked. Thanks for the confirmation all!