How to create cheap four wires untwisted ethernet cable for short distance

[neonix]

You don't have to buy UTP eight wires cable to create local LAN network.

You can use any wires you find, with 100BASE-TX standard, and IEEE 802.3u-1995 specification.

I don't know what is maximum distance, but it work in short distance in home bulding, between rooms. If you have modern switch/router you don't have to care about crossover.

https://www.reddit.com/r/HomeNetworking/comments/zddylt/ethernet_over_untwisted_phone_lines_it_works_how/

[gadget42]

after glancing frequently in the garbage bins most everywhere, we have a never-ending supply of cat5 and cat6 raw cabling of many various lengths. even pieces that had somehow been physically damaged(rodents?) and were used to pull in new cabling are fine to cut down for short runs. just make sure to put new ends on them and always mark and test them before usage(keeping good documentation/notes is wise, ymmv).

[CentralWare]

I don't know what is maximum distance...

Ethernet copper is rated based on the thickness (guage) of the copper and the shielding of each strand onto the next.
The cheapest method of room-to-room IF you need two or more connections is to share a single 8 strand CAT5 which is split into two separate channels simply based on which wire goes to which pin.

Pins 1, 2, 3 and 6 are channel 1, the others are channel 2.  You'll get two 100Base-T connections for up to 30~50 feet depending on the cable gauge.
Any faster than 100mbps and you'll get cross-talk over 10~15 feet; again, depending on the cable itself.

There are plenty of docs online that define CAT5/6/7/etc specifications, wiring and pin-outs, cable length and gauges, etc.

[gadget42]

poked around a bit and this was decent to get folks started:
https://electrouniversity.com/how-to-test-ethernet-cable-with-multimeter/

multimeter testing is fine for the home hobbyist but if you plan on a more professional endeavour(install/testing/troubleshooting/etc) then a more purpose-built tester is warranted.

right now the Klein Tools VDV526-200 Cable Tester is fairly popular and in the $50-$60 range currently(at that bezos place)

[CentralWare]

Evenin' @Gadget42!
I'm cheap   Here's a $14 tester that does everything you need to determine if COPPER is aligned properly...  whether or not it's GOOD copper and/or shielding is another story.

[neonix]

Here is switch that offers 10Mbps at 200m extended distance (100m is standard).
100m= 328 feet
200m= 656 feet
Does this switch use 2 x 100BASE-TX on 8 wires instead 4 wires (100m)?
 
https://www.planet.com.tw/en/product/fnsw-1601-v9

BTW. In 1995 when 100BASE-TX standard was published, they could create 2 wires half-duplex transmission, upload and download on 2 wires. In this way old telephone cables could be used on short distances. 

[neonix]

https://www.epanorama.net/blog/2023/06/22/passive-ethernet-hub-circuits/

How does this passive ethernet hub works?
Does both computers have the same static ip adress or dynamic DHCP?
Can I connect 4 computers using only one 8 wire cable?

[Rich]

Hi neonix

... Does both computers have the same static ip adress or dynamic DHCP? ...

All computers must have unique addresses. That's a requirement for Ethernet.
How the computers get their addresses has nothing to do with the hub. The
computers can have static addresses, receive an address via DHCP from
another device connected to the hub, or a combination of both.

... How does this passive ethernet hub works? ...

When one computer talks, the message goes out to all of the computers, not
just the one it was addressed to. The other computers see the message was
not addressed to them, so they ignore it.

If more than one computer tries to talk at the same time, you have a data
collision, and the computers will have to try again after a delay.

... Can I connect 4 computers using only one 8 wire cable?

No. The passive hub contains diodes that are used to connect the computers.

[neonix]

If this device works the same way like active hub, then how many devices I can connect to one local network using passive hub?

I was thinking about creating two passive hub and connect them to router using 2 four wire cables combine in one UTP CAT5 cable.

[vinceASPECT]

Hello forum,

over all the years, the only thing i learned on cabling seemed to be that for connecting a single PC to one other single PC......you need a "crossover ethernet cable" not a regular ethernet cable....?

i  believe that's right.....

......i can imagine network engineering is an extremely contrived and responsible position.......you hear all manner of stories .........such as large networked PC systems having issues due to network cabling passing by large old metalic heating systems and the networking passing too close to the cables feeding that heating......

thx

[yvs]

> over all the years, the only thing i learned on cabling ...
>
   in 90s (before Ethernet over twisted pair) it was quite common to use a coaxial cable as a shared medium