such a thing as a QSFP 10gbe rj45 transceiver?

thetoad

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Feb 10, 2021
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Is there such a thing?

or would one need a QSFP->SFP+ adapter and then a 10gbe rj45 transceiver in it? (or a mess with breakout cables, I was thinking a QSFP+ tranceiver could fake the breakout cables and basically treat only one of the 10gbe lanes as "active").
 
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LodeRunner

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No, you'd need a QSA and a RJ45 SFP+ as far as I know. Breakout is passive optical or active electronics in the form of a DAC, not RJ45.
 
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thetoad

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I meant that a QFSP RJ45 would be a "fake breakout" connector. i.e. wired like a breakout, except in practice only one of the breakouts would be connected to the single rj45 sticking out of the transceiver.

re what you said though, I posted a thread a while ago, that apparently dell supposedly sells a breakout to rj45


it doesn't quite makes sense to me (though if one searches for part numbers its listed all over) as I can't imagine a QSFP+ switch being able to to do 10/100/1g/10g (I'd imagine they are limited to 10g or perhaps 1g/10g)
 
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i386

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I can't imagine a QSFP+ switch being able to to do 10/100/1g/10g (I'd imagine they are limited to 10g or perhaps 1g/10g)
Mellanox switch-x2 based switches can do at least 1GBE. My guess is that they work with <1GBE too, but they don't write it in the datasheets becuase nobody should use fast ethernet :D
 

LodeRunner

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I meant that a QFSP RJ45 would be a "fake breakout" connector. i.e. wired like a breakout, except in practice only one of the breakouts would be connected to the single rj45 sticking out of the transceiver.

re what you said though, I posted a thread a while ago, that apparently dell supposedly sells a breakout to rj45


it doesn't quite makes sense to me (though if one searches for part numbers its listed all over) as I can't imagine a QSFP+ switch being able to to do 10/100/1g/10g (I'd imagine they are limited to 10g or perhaps 1g/10g)
Oh, that thing again. As far as I have been able to search, that is the only hit for that type of cable. The specs claim what you say but the picture is for a standard DAC. Neither FS.com nor 10GTek which will usually have any combo of connectors you’d need offer such a thing.

Call Dell and see if you can get a hold of someone who can actually confirm if that unicorn exists.
 

thetoad

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this thread was wondering about qsfp transceiver, not a breakout cable. I was just hypothesizing how such a transceiver could work (i.e. like a breakout cable with only 1 of 4 ends, but not a breakout cable).
 

thetoad

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eh, pretty close. It reminds me (I believe) and IBM pcmcia card that i had that came with a modem and ethernet adapter in one.
 

Sean Ho

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Is it that you need to connect a QSFP+ NIC to a 10GbaseT link? LodeRunner's initial reply covers that, with a $15 QSA adapter (QSFP+ to SFP+) plus a $50 SFP+-to-RJ45 transceiver (e.g., S+RJ10). I have several QSAs working fine with SFP+ DACs. As you say, they only expose one pair to the SFP+ end.

If the question is that you have a QSFP+ switch port which you wish to break out to 4 10GbaseT links, you'd probably have an easier time chaining a separate 10GbaseT switch for those links.
 
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thetoad

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I know one can chain a QSA to a an SFP+ RJ45 transceiver. I was simply wondering if there was any device that did it all in one without the need for chaining. And his link above gave me an example of it not being a single RJ45, but a dual, which is what I said, close enough.