Can an SFP+ module down-convert 10Gb to 2.5Gb? YES

[marked23]

I tried looking this up online, and I came up empty. I even asked ChatGPT... which was confidently incorrect. So I'm posting this here.

I bought a couple HPE Ethernet 10Gb 2-port 530SFP+ cards. My switch's 10Gb ports are already occupied. So I'll use a 2.5Gb port to feed my desktop that has one of these SFP+ cards. As far as I can tell, the card only does 10Gb. The OS only sees it as a 10Gb connection.

I used a H!Fiber ASF-10G-T (1.25/2.5/5/10GBase-T) module. Works great. I copied a big file across the network at ~250MB/s.

Success!

 

[blunden]

Thanks for taking the time to post about it.

Some modules do it properly, yes. Most don't handle bidirectional traffic correctly however, at least based on other threads on this forum. I summarized it in the post below, which also links to some threads with more details.

https://forums.servethehome.com/index.php?threads/brocade-icx-series-cheap-powerful-10gbe-40gbe-switching.21107/post-421031

 

[marked23]

> Most don't handle bidirectional traffic correctly

Hmm.. I went back and checked.
Indeed, I did notice a slowdown when copying one way vs. the other.

From desktop to server:

From server to desktop:

I'm just playing with my homelab, so I'm not at all disappointed. And I can't even be sure what to blame.

Oh, maybe you mean bi-directional simultaneously?
I'll have to try that later.

 

[TonyArrr]

I even asked ChatGPT... which was confidently incorrect.

I think this might be my new tagline