(potential) ConnectX-4 QSFP28 OCP Multi-Host MCM4431M-GCAN

eduncan911

The New James Dean
Jul 27, 2015
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Could these be flashed to 40GbE firmware?

And good find, as I'm starting to find more and more OCP machines. Though, the version changes and incompatibility between the versions is a PITA.
 

efschu3

Active Member
Mar 11, 2019
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Well it's still OCP 2. But with connector A (which gives 8 Lanes) and connector B (which gives the card additional 8 Lanes). If I place a "standard" PCIe 16x Card in an 8x Slot, the Card will work properly, so I guess an OCP 2 Card with con A&B will do the same.
 
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Docop

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Jul 19, 2016
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Has having 4mac.. Is it fully compatible with any 100g qsfp28 module ? But with an mpo module, how do you get like 2x 25g from this ? FS module 100g are only split to 4 stream of 25g and using a fiber breakout mpo to 8fiber, you cannot get or mix 4 fiber together to form a 50g feed. So only used to give 4x 10g maybe..
 

efschu3

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Mar 11, 2019
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I think I did not get you completly. What I want do to is to test if these cards work on OCP 2 port with connector A only (limiting the card to PCIe 3 8x, but this is OK for me) and if so, I will try to crossflash them to a CX4 100GbE and use this single 100GbE Link. I do not want to use this as breakout (for now).
 

Docop

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Jul 19, 2016
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8x slot will give indeed better. but a 25 in 4x it's 2.1gbps and 50 give 2.4g of transfer.
 

eduncan911

The New James Dean
Jul 27, 2015
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I see the CX4421a variant (dual port SFP28, 50Gbps) comes in OCP 2.0 form in the Hyve server that will be here next week.

Since most of my hardware is QSFP, I'll pick up one or two of these as well to see how they work.

Hopefully I can flash them to some 40 GbE compatible firmware. I'm pretty sure Mellanox doesn't support breakout (e.g. 4x 10GbE).
 

i386

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Mar 18, 2016
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Hopefully I can flash them to some 40 GbE compatible firmware. I'm pretty sure Mellanox doesn't support breakout (e.g. 4x 10GbE).
In one thread here in the forums somebody posted that they could succesfully flash a 50GBE model with the 100GBE firmware. I would try that even when it will be limited by the x8 lanes :D
 

efschu3

Active Member
Mar 11, 2019
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So, the cards work with the PCIe->OCP2 Adapter. But for now I'm not able to crossflash them to 100Gb.