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Actually it is a two part question.

1.Since an ethernet connection only requires 2 pairs (green and orange), is it feasible to wire blue and brown pairs to a different Lan port of a router and achieve wired internet access on two separate machines through the very same cable?

  1. Since it is definitely doable, how will internet performance be affected -Speed, ping, etc?

The reason I'm asking is because I am not able to poke more holes in my walls, and wireless connection is not an option when nearly 35 meters away from the router.

EDIT: Thank you, guys, for the quick replies. Indeed, using a switch is much easier. I just didn't know devices like those existed!

Aris Kon.
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    gigabit ethernet uses all 4 pairs, fyi. – Richie Frame Dec 20 '15 at 09:23
  • I will not be transferring files through homegroup, my connection is 9 Mbps at its peak and my network ethernet's speed is 100 Mpbs. Still not able? Edit: Sorry if I sound silly, but I have little to no knowledge on ethernet connection. – Aris Kon. Dec 20 '15 at 10:27
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    First the cabling standards disallow using a single UTP cable for more than one connection. It may be possible, but you would be better off using the cable to connect to a small, 4-port switch. Second The Wi-Fi standards give you a distance of 100 meters, just like wired UTP, so I'm not sure why you think 35 meters is too far. – Ron Maupin Dec 20 '15 at 15:52
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    Why not just use a switch? – Michael Hampton Dec 20 '15 at 16:00
  • In case you need the networks to be logically separated, you can still use a switch - it just need to be a managed switch (at each end of the connection). – kasperd Dec 21 '15 at 15:26

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For 100Mb/s connections, this is doable but not recommended. Doing that, you will greatly increase interferences and noise between the copper pairs. Predicting how this will affect connection speed is difficult: in the worst case, you will have many retransmitted Ethernet frames, leading to lower throughput and latency spikes.

For 1Gb/s (or faster) connections, this can not be done, as they need all the four available pairs.

shodanshok
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  • it's also not possibile if you're using PoE (802.3af or 802.3at) – eldblz Dec 20 '15 at 23:23
  • "*you will greatly increase interferences and noise between the copper pairs*" Do you have any reference for that claim? If that was true, then how would GigE work over the same physical wires? – David Schwartz Dec 21 '15 at 18:32
  • GbE uses a different encoding at the physical layer. Fast Ethernet (100 Mb/s) is much more primitive in that regard, and its is more prone to crosstalk interference. Anyway, for short distances it is indeed possible to split the cable in two different ethernet channel. For longer distances, it can cause dropped/retransmitted frames. – shodanshok Dec 21 '15 at 18:45
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Yes this is possible and I did this about 10 years ago.

Looks like there are still vendors selling splitters designed for this purpose: http://www.4cabling.com.au/cat-5e-cable-splitter-data-data.html?utm_source=google_shopping&gclid=Cj0KEQiAwNmzBRCaw9uR3dGt950BEiQAnbK96zFs3lchJbcbSeLaRYOwTg0PiQX2bSxEEfa09btjYxMaAvjz8P8HAQc

But as already mentioned this drops you down to 100mbit. I think a better solution is using a cheap switch and plugging the cable from your router into one port and the two devices into it. This won't have the 100mbit issue and will scale beyond 2 devices. A Google for "4 port Ethernet switch" will return many low cost switches that will do the job well!

Nath
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