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Running tone traces on a ethernet network and I just ran into a situation where the tone for two separate jacks registers to the same cable in the network closet. I pulled the wall plate and verified there are no cross wires or splices at the termination drop; both jacks have their own individual cables. However, test comes through full green on only a single cable.

Going above ceiling to see if there is anything weird going on.

Question: why would tones sent through two separate cables both register on the same cable?

(Using Fluke Intellitone Pro 200)

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    Cool story, bro. What's your question? – Esa Jokinen Aug 4 '17 at 16:49
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    sorry, my inner monologue took over, added question – mlxs Aug 4 '17 at 17:13
  • 1) if it's an old installation, maybe someone split the cable at some point in the past, so that two pairs go to one place and the other two to another. (you can run 100mbit on 2 of the 4 pair) 2) crosstalk between the cables is possible with toners. I'm not familiar with the state of the art but older ones i've used did that regularly. – Dan Pritts Aug 4 '17 at 22:56
  • @DanPritts There is a lot of that on this network, but I replaced the jacks and both have all 8 pairs terminated. There's a number of drops that are split to x2 100mb x1 RJ11 and my toner is picking up a lot of cross talk. – mlxs Aug 4 '17 at 23:35
  • quick and easy way to verify, plug both ends in to switch/pc. if you get a 1Gb link, you have all 4 pairs going all the way through. If it doesn't work, it's not a guarntee there is a problem, older wire might not do 1Gb. . ... and you can't get 2x 100Mb + another pair on an RJ11 (presumably for voice) on a standard category5/5e/6 cable. 100Mb needs 2 pair (4 wires), and a standard cat cable has 4 pair (8 wires). – Dan Pritts Aug 5 '17 at 4:51
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A few weeks later they decided to move forward with re-cabling their entire network. In the midst of the install, I found a 12-port patch panel literally cocooned inside the cable trunk. Apparently, the original installer hadn't made the cables long enough so he used a patch panel as an impromptu extender. Because he had been splitting cables, he had to split them again at this patch panel, but used standard ethernet cables to run the last 15 feet to the switches. Explains why I was getting tones on multiple lines in the network closet. There were also at least 7 ethernet runs daisy-chained off other drops, further example of this guy's preference for speed of install over quality of signal. Because he had messed up on the cable length, the cable trunk was laying across three fluorescent light ballasts and was so taught I couldn't get it more than 4 inches off the drop ceiling panels. It was at that point I told them I can either re-cable the entire network or they can pay me for work done and figure it out on their own.

New network install is scheduled for this weekend =)

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