Within an Optical Transport Network (OTN), where two nodes are connected via ODU, is it possible to configure this link uni-directional?

I realize this is a very unusual application, but it is an actual use case that I'm studying, as we absolutely need no back-channel. As such, the return paths along the particular ODU path in the network could be used for other connections.

2 Answers 2


Could it? Yes. Will it ever in normal deployments using standard equipment? No, probably not. You would have to build or design your own equipment and link management protocols to implement it.

It is effectively impractical to do because you can simply take a normal connection on commonly used equipment and disable traffic flow of any meaningful level in the software implementation (firewalls etc.). It is 'one way' enough via that method that it is undesirable to go for some kind of custom solution.

  • Thanks for the information. As I mentioned, I want to make use of the back channel for another ODU connection. Disabling traffic flow will affect the data plane only, that's understood. But I understand from your answer that the ODU connection requires the equipment and link management (which goes over some frame headers I assume). This means for me, using standard equipment, I cannot use the back channel for other means.
    – Bash Frank
    Commented Dec 16, 2022 at 16:44
  • That is correct, without custom made equipment and protocols, you cannot arbitrarily 'misuse' part of the cable designed for another purpose. For what you want to do, you should look into DWDM fiber optic which allows you to use a single fiber or pair of fibers for multiple wavelengths of light signaling and therefor multiple 'connections' per fiber. Commented Dec 19, 2022 at 15:22

On the logical level you could filter or simply don't use the other direction. On the physical level and layer most protocols used over OTN require both directions to work - there are exceptions and sometimes a unidirectional connection can be forced.

Effectively, I depends on what exactly you run over the OTN and whether your gear supports unidirectional links.

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