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networking nerds: why would an 8P8C rj45 female jack read reversed pairs? (lemmy.zip)

submitted 1 day ago* (last edited 1 day ago) by hodgepodgin@lemmy.zip to c/asklemmy@lemmy.world

9 comments fedilink hide all child comments

So, not sure if I’m making myself clear, but I recently just witnessed a female RJ45 jack need to be reterminated since it was only receiving PoE but not data. This is probably because the PoE pairs still function with connectors 1 to 8 reversed. We know this because our cable tester showed each conductor reversed with a reflector plugged in. As in, 1-8 should’ve mapped to 1-8 but instead mapped to 8-1. A coworker of mine pulled the head off and examined the pairs, but each color and stripe matched perfectly.

Not sure what happened here. I think it was probably human error since we encounter that sometimes when repairing work that cable contractors do. However, I could see myself making the same mistake since the pairs were all pushed in correctly.

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[–] klymilark@herbicide.fallcounty.omg.lol 10 points 1 day ago* (last edited 1 day ago)

Yeah, a crossover cable is pins... 3 and 6 switched? iirc. I did not remember correctly, it's 1/3 2/6, been a while. The greens and oranges swap places

Either way, if the cable was reading completely reversed, assuming it wasn't fixed by rewiring it, check the patch panel to make sure that's wired right if you haven't. One of the first mistakes I made in college was wiring a patch panel backwards xD

Besides that the only thing I could assume is the direction one end got termed was just backwards. If someone's in a rush I could see them just absentmindedly mounting the head backwards.