I tried to research this, but cound't find a specific answer to my scenario. So I tried to understand the necessary background knowledge myself, hopefully I came to the right conclusion.

If I want to temporarily connect two switches via a patch cable (assuming sufficient cable quality). If I use a stranded patch cable, Cat6 AWG24 UTP, which is suppose to support 1000BASE-T. I calculated the maximum length to be 85m: 0+(102-0)/(1+0.2)=85 [H+C where C=(102-H)/(1-D)] according to ANSI/TIA/EIA 568-B standard.

Assuming it's possible to patch (attach a RJ45 plug on either side) the horizontal cable (is it?), would the range increase to 90m? And since can get rid of the the 2 plugs and jacks used to connect the device in a setting with a permanent link could I use the full 100m length (instead of 90m +2*5m)? Although I assume sure this "whole scenario" is simply not included in the definition for the specs (as far as I understand the basis for the specs are that the horizontal cable was intended to always be used with patch cables). But how are chances that this will work?

Note: this will not be a permanent setting, it's just to bridge the time gab until I can get the "real network engineers" to fix the situation.

Disclaimer: I asked a similar general question which got closed for very good reasons. So I tried to revise and make much more specific so it's not covered by the other answer anymore. I also added the actual scenario (what exactly I want to do).

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    That's very much the same question you've asked before. Note that the formula you're using looks sound, yet it's not part of an IEEE spec, so there's no quarantee it'll work out. IEEE specs allow up to 90 m of solid wire, 10 m of stranded wire and four connections. – Zac67 Aug 22 '20 at 11:35
  • @Zac67 It's similar yes, but this time very specific (asking my first question I didn't have the necessary knowledge)- The formula is from the ANSI/TIA/EIA 568-B standard (I added that to the question). I know the scenario is out of the defined specs (they don't include horizontal cables as direct connections), but using a 100m solid cable instead of "90m solid + 2x5m stranded (+jacks/plugs)" sort of "sounds" like it shouldn't lead to signal degradation. Unfortunately I don't have the in depth network/physics knowledge to verify that, that's why I'm asking. – Albin Aug 22 '20 at 12:09
  • Assuming it's possible to patch the horizontal cable - if I understand correctly, you're trying to patch together two runs of horizontal cable. That would be an excellent opportunity to connect another switch in the middle, so each link is far below 100 m and well within specs. – Zac67 Aug 22 '20 at 14:10
  • @Zac67 not quiet. With patching I meant putting an RJ45 plug on the cable (I will correct it in the question). So it would be one 100m horizontal cable directly connected to the two switches (instead of a 85m stranded "regular" patch cable). – Albin Aug 22 '20 at 14:22
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can post and accept your own answer. – Ron Maupin Dec 17 '20 at 20:53

Unfortunately the answer is, it depends.

Practically speaking, even if you meet the cable specifications, there’s a good chance that your equipment may not. Some manufacturers cut corners and can’t drive cables at the maximum length, assuming most installations never push the specification limit.

Hopefully you’re using commercial grade equipment.

  • Yeah it's all commercial (enterprise level) and I would not make the solid core patch cable myself, but let someone with the appropriate equipment take care of it. Good point warning me about the short failing from the devices themself I will check that with the manufacturer for the current equipment (I think they are Extreme Network switches). Your depends was only in regards to the equipment, or any other aspects as well? – Albin Aug 22 '20 at 14:23
  • I generally agree with this answer, but as an anecdote: I currently have two C3560-CX switches connected via a 480ft (146m) cat6 cable at 1Gbps at one of our COVID drive-thru testing sites, due to site layout constraints. So although I would never recommend pushing beyond the specs under normal circumstances, you might be surprised what you can do with the right equipment. – halfmetaljacket Aug 22 '20 at 18:56

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