If fibre goes down in a forest, does the twisted pair hear it scream?

So at $work[0] we’re trying to bring up a new service for a customer. It’s a 2meg service from T, which terminates on our side like so:

fibre -> managed media converter -> twisted pair -> router

We think we’re ready to turn it up and a T technician is booked. For 01:30am due to customer requirements. Sigh.

Technician reports he can’t see either the media converter nor the router. He’s on the “basement switch” (a designation which means nothing to yours truly, especially at that hour of the morning). Eventually my sleep deprived haze allows me to parse that he is on a switch in the facility and can’t connect to the service.

Except our understanding is that their end of the service doesn’t terminate in the facility. Their switch is in one meet-me-room but it had cable tray / riser capacity issues. So this service’s fibre went to the meet-me-room at the other end of the building. Where T doesn’t have a switch. But they did have some spare fibre already pulled from an exchange. So a fibre tie later and our service terminates elsewhere. And in my blubbering state I can’t convince the technician of this. Cutover canceled. Furrfu.

So what does the subject have to do with this saga I hear you ask?

The technician wanted me to pull the twisted pair from the router to check for link protocol going down on an interface of the switch he was logged into to. Even presuming he was on the right switch, my original reaction was that it wouldn’t work because the media converters act like bridges, not repeaters, and the link protocol wouldn’t change at his end.

I wanted to confirm / deny this ungodly hour of the morning theory, but my Google-fu appears to be suffering 5 month old child process lossage. JohnF did the heavy lifting for me and turned up this question and answer which covered a similar scenario. The pertinent response that address my question is:

Coming in a bit late here, but…

Has the OP looked at how the media converter is set up? Many media converters have a test mode where a down link status is not passed from one side to another. Once you take it out of test mode, it will pass status. Usually it’s a small push button, or a switch.


So the answer to my question is: it depends!

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