LX2160ARDB 25Gb compatible issue

[howardlu1]

Hi, All:

I met one problem about 25Gb connection problem, I tried to use "Cisco QSFP-4SFP25G-CU3M Compatible 100G QSFP28 to 4x25G SFP28 Passive Direct Attach Copper Breakout Cable" or similar cable and connect to one 25Gb SFP28 and one 100Gb QSFP.

And then using 25Gb SFP28 on LX2160ARDB, and another side is 100Gb QSFP and configured it as 25Gb.

But they showed no link and seems no Link up showed on both devices respectively.

By the way, another side is  a general server , and ever used in other device with same scenario but no problem on that.

Does everyone have same problem on LX2160ARDB?

The module I used is FS QSFP28-SR4-100G and Mellanox MMA2P00 SFP28.

Thanks,

Howard.

[howardlu1]

Hi, Yiping:

Thanks a lot, and I saw RS-FEC could be enabled by MC-BIN only, and we cannot enable/disable it by general MC-BIN version, isn't it?

Thanks,

Howard.

[yipingwang · Accepted solution]

Correct. It was in the DPC file. If you don't make the changes, the MC firmware will overwrite anything you do.

LX2 RDB has QSFP+ cage to support 40G XLAUI. I have seen a 40G breakout into x4 10G SFP+.

Each lane operates at 10.3125Gbps.

for 100G, this is x4 25G-AUI. If a QSFP28 is used, then the Inphi in the path may need reprograming if it can support the 25G-AUI lanes.

[yipingwang]

The only thing I can suggest now is to see if RS-FEC enabled makes any  difference if it is not enabled already.

Obtaining 100G breakout cable to try will take some time. Would have to order and then try in the lab.

Has been over a year since I have been in the lab. So finding the equipment to test might be another hurdle.