Trying SFP+ for the first time, getting 'Rx fault' error..huh?

Hi all,

Breaking out SFP+ for the first time, given how much cheaper the NICs are say compared to X550-T2’s. However, I’m getting this error in Unifi when connecting this to my 16XG. Thoughts?

I always switched the ends of the fibre cable around, no dice.

Appreciate any help.
cc: @SgtAwesomesauce

Are you using DAC or transcievers over fiber?

If using transcievers, you may have a bad cable or the strands mixed up.

Matching Transceivers? That fault could be that the two ends do not match in wavelength or are different types. (eg LED or Lazer)

Or even better, incompatible with Unifi.

Transcievers over fiber. They were specifically chosen by the retailer as they have sold the same config to local telcos and confirm they work on 16XGs.

What do you mean? One side of the stands has a yellow sheath. So I tried them “both ways”, i.e. on the 16XG end, either the yellow-end is on the left or on the right. There isn’t any other way to plug them in?

Two identical units, and the retailer confirms the set (NIC + 2 SFP+s transceivers) are compatible with 16XG.

It may be down to the fibre though. In any case I have bigger issues, the NIC isn’t compatible with XCP-ng. It did appear under a lspci | grep Eth in linux though.

That could also be it. When one end of the fiber does not reply, the line is marked as “down”, could be treated as an “Rx Fault” (=nothing recieved) aswell.

1 Like

Right, that makes a lot more sense!

I’m going to see if I can get the NIC to work in linux, then check if UniFi sees it.

This is odd,

# lspci -tv |  grep Eth
             +-01.3-[09]----00.0  Tehuti Networks Ltd. TN9310 10GbE SFP+ Ethernet Adapter

# lshw -class network -short

H/W path                Device           Class       Description
/0/100/1.1/0.2/0/0      wlp3s0           network     QCA6174 802.11ac Wireless Network Adapter
/0/100/1.1/0.2/1/0      wlp4s0           network     Wil6200 802.11ad Wireless Network Adapter
/0/100/1.1/0.2/2/0      enp5s0           network     I211 Gigabit Network Connection
/0/100/1.3/0                             network     TN9310 10GbE SFP+ Ethernet Adapter

There’s no ‘device’ for the Tahuti networks card?

Update: There’s a driver for this chipset that needs to be installed. Ugh, I don’t think that’s going to play well with XCPng; going to source an intel SFP+ NIC or X550T2 card, whichever is cheaper/easier.