Normally, if you're doing "single fiber optics" it basically means you have a single color/frequency in one direction, and another color/frequency, which is slightly offset. e.g. They say blue for send, and purple for recieve, or something like that. It's hard to screw it up, but I've definitely tried :)

On Sun, Oct 15, 2023 at 4:21 PM Stephen Hemminger <stephen@networkplumber.org> wrote:

On Sun, 15 Oct 2023 10:30:48 +0330
Alireza Sadeghpour <alireza0101sadeghpour@gmail.com> wrote:

> Hi,
>
> I am trying to establish a uni-directional Ethernet link where a singular
> fiber is used to transmit data to the receiver in the DPDK environment. The
> Rx of the transmit side and the Tx of the receive side are not physically
> connected, like in a Data diode scenario. The ethernet controller on both
> sides is intel 82580.
>
> my problem is that when I detach the RX line from one side, both sides'
> links go down.
>
> Could anyone please give me some advice to solve this problem and establish
> a valid unidirectional ethernet link?

This is not a DPDK problem. Trying to non-standard configuration like this
requires detailed knowledge of the hardware registers, and likely driver specific
changes to do that.

It is possible to bring up device in normal full duplex mode and even setup
the receive queues but ignore them. But that doesn't sound like what you want.