Juniper LX4 optics & Mellanox CX3/SX6036 compatibility

bryan_v

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Nov 5, 2021
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Quick question:

Has anyone had any success with 40G LX4 transceivers in Mellanox CX3 cards and SX6036 switches (specifically Juniper QSFP+ 40G LX4 LC transceivers)?

I'm about to run optics throughout the house, and MTP/MPO cables are so much more expensive than LC/LC cables for multiple runs ~70-150 ft each (like 3x more expensive). A whole slew of Juniper LX4 trancievers hit fleabay so thinking of picking up a few to give me 40G to both mine and my wife's offices.


There was a bit of a discussion on the Brocade megathread though I didn't see a resolution, so thought it might be better just to start a separate thread
 

NablaSquaredG

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Aug 17, 2020
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You could also use 40G-LR4 / LR4-Light transceivers

Advantages:
- They use Single Mode fiber which is even cheaper than Multimode (e.g. OM4)
- Can also be found for very little money (ebay, e.g. Kaiam XQX2502)

Disadvantages:
- Only work in certain slots in SX6036 (1,3,33,35), but backplane FRU can be modded to support it in all slots
(- Infiniband 40G only supported once you've applied a custom programming)
 

bryan_v

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Lol I thought LX4 transceivers were cheaper than LR4, but I think fleabay was hiding them from me. Those XQX2502 look great, and I think I got fleabay searching properly now.

Now that I know that LR4 transceivers are available for cheap, SMF is definitely going in the walls instead of MMF. Something like this should work right? Singlemode Duplex 9 Micron Fiber Cable - 2mm Jacket OFNP - Infinite Cables

Also that is super wierd that it only works in certain slots. I'm guessing SR4 optics don't have the same issue?

I'm assuming these AOI transceivers are pretty decent as well? AOI AQOLBCQ4EDMA0878 QSFP+ 40G-LR4 Lite 2km 1301nm (Fedex Expedited)>100pc | eBay
Or should I stick to big brand name ones (e..g FS, Cisco, etc and Kaiam modules)?
 

NablaSquaredG

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Aug 17, 2020
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Also that is super wierd that it only works in certain slots. I'm guessing SR4 optics don't have the same issue?
No, SR4 optics don't have that limitation.

Although LR4-Light modules only need roughly as much power as SR4 modules, they are still treated as regular very high power LR4 modules.

I'm assuming these AOI transceivers are pretty decent as well? AOI AQOLBCQ4EDMA0878 QSFP+ 40G-LR4 Lite 2km 1301nm (Fedex Expedited)>100pc | eBay
Or should I stick to big brand name ones (e..g FS, Cisco, etc and Kaiam modules)?
Yeah they're probably fine
 

bryan_v

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This is what I could find:

For the FS UNIV modules:
Arista Networks 40G QSFP+ QSFP-40G-UNIV Transceiver - FS (right at the bottom are all the sheets)
Datasheet direct link: https://img-en.fs.com/file/datasheet/40g-qsfp-plus-univ.pdf

For the cheap 40G Arista UNIV modules on fleabay (Arista QSFP-40G-UNIV XVR-10071-20):
Source: Transceivers & Cables - By Type
Q&A: https://www.arista.com/assets/data/pdf/Whitepapers/QSFP_40G_UNIV_FAQ.pdf (dunno how useful that one is)
Consolidated Data Sheet: https://www.arista.com/assets/data/pdf/Datasheets/Transceiver-Data-Sheet.pdf (they don't seem to have separate one for each module)

FS BiDi modules:
Product page: FS for Mellanox QSFP-40G-SR-BD Compatible 40GBASE-SR Bi-Directional Duplex LC MMF Optical Transceiver Module - FS
Data Sheet Direct link: https://img-en.fs.com/file/datasheet/40g-qsfp-plus-bidi.pdf

The BiDi modules are the most promising since they use LC cables and have only two relatively low power VCSELs.

Let me know your thoughts.

Cheers,
Bryan
 

NablaSquaredG

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Aug 17, 2020
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The UNIV ones will probably cause issues, my magic transceiver database says they're coded as (at least the FS ones) 40G Ethernet: 40G Base-LR4 with the 3.5W power class. I don't know exactly whether the switch looks at the power glass or the Transceiver Type / Codes in byte 131 - 136 of the EEPROM, but I suppose it looks at the transceiver type

The FS BiDi transceivers are not in my database, but according to the datasheet they're 40GBASE-SR, so it should be fine
 
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llowrey

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Feb 26, 2018
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The Arista UNIV claims to support both SMF and MMF but generally... the two don't mix. There are solutions but probably not anything any of us wants to deal with.


The Arista 40G UNIV def works between my SX6018 and CX-3s. My Cisco BiDi's def do not.

The Kaiam XQX2502 LR4-Lite transceivers (SMF) also work just fine. I can't confirm whether or not the Kaiams work w/o the firmware hack to enable high power transceivers.

There seems to be a cycle between MMF being the most economical and SMF being best. At this point I would probably just pull both.