QSFP+ 40GB to 10GBase-t possible?

Notice: Page may contain affiliate links for which we may earn a small commission through services like Amazon Affiliates or Skimlinks.

Airz

New Member
Jan 22, 2014
23
2
3
I've already got a bunch of servers and clients with 10GBase-t copper NICs installed but I'd like to upgrade the switch. I've seen an Arista I like the features of but it's only got QSFP+ 40Gb ports on it. I've looked for 10GB SFP+ Arista switches but they seem to be way more expensive second hand than the 40Gb (at least the ones with SDA and VXLAN). Is there a way to get from QSFP+ to 10GBase-t via converters or breakouts as I'd like to avoid having to replace all the existing NICs.
 

koifish59

Member
Sep 30, 2020
66
19
8
I'm interested in knowing this too. I have cat8 cables planning on installing and I'm looking to go from QSFP+ port to ethernet cable if possible.

I've looked and cannot find a QSFP+ to RJ45 module.
 

ske4za

Member
Feb 4, 2019
80
45
18
HPE has PN 838327-B21 (QSFP+ to dual 10GBASE-T) but YMMV as I have no experience with it.

Another option, although cumbersome and expensive, is to just use 10G fiber media converters. Some of them say they support DACs, but YMMV here too.
 

Dreece

Active Member
Jan 22, 2019
503
160
43
There is a QSFP to SFP transceiver adapter, effectively a QSFP transceiver which goes into the switch and you plug into that an SFP+ transceiver... though not sure if the Arista supports it.

There are quite a few breakout cables out there, however what you can and cannot do is determined by the switch itself as in does it permit the port to breakout, for example 40Gbe to 4 x 10Gbe etc.
 

Airz

New Member
Jan 22, 2014
23
2
3
Yeah I've seen the QSFP to SFP media converters however on fs.com they specifically state their 10Gbase-T SFP transceivers aren't compatible with them.
The HP PN looks good but given that they seem to be only the provider I wouldn't be surprised if they only work on specific HP switches. I've been combing the internet but I really don't think the manufacturers expect you to try and go from QSFP to 10Gb rj45. I think I may just have to bite the bullet and get an SFP+ Arista switch instead of QSFP. It will be more expensive but at least I know it will definitely work.
 

Rand__

Well-Known Member
Mar 6, 2014
6,626
1,767
113
What's the reason not to replace the NICs?
O/c if they are built in its not an option, but if not... Cheap MLX 40G cards can be had all the time
Else - a cheapish Base-T 10G switch with 40G uplink or (depending on how many boxes we're talking about) a couple 10G fibre uplinks...
 

Fallen Kell

Member
Mar 10, 2020
57
23
8
I was just looking into this same issue myself and was about to post a question to see if anyone had used the QSFP+ -> SFP+ converters with a SFP+ 10Gbase-t module. Guessing from the responses here the answer is it hasn't been tried.

I was debating just buying one of the adapters to test myself but I really like to know that it works before I attempt it so I can more quickly debug any issues.
 

Rand__

Well-Known Member
Mar 6, 2014
6,626
1,767
113
Now that you mention it I think i tested it and it worked iirc, but its been a while, so not entirely sure any more;
totally forgot about the SFP+ -> 10G converters