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Picture of How-to make your own Ethernet
rj45_splitters.jpg
rj45_wallmount_1.JPG
With an Ethernet "splitter", you can simultaneously connect two computers (or other network devices) on one Ethernet cable. You can buy Ethernet splitters for approximately $ 20.00 USD but you also can make your own.

Context:
One office, one ethernet jack and two computers, or
One living room, one ethernet jack and one HTPC and one XBox.

If you can't realistically (without tearing apart walls or renting a scissor lift) pull one more ethernet cable from the patch panel to the office / living room etc. you can consider the use of an Ethernet "splitter".

I'm assuming all the four pairs of the ethernet cables are properly connected within the ethernet wallplate and the patch panel.
 
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Step 1: What you need

Picture of What you need
In order do make your own Ethernet splitters you'll need the following:

  • Two RJ45 Crimpable Plug
  • Four RJ-45 keystone jack
  • Short Ethernet Cable Scrap (approximately 2 feet)
The tools you'll need:

  • RJ45 Crimp Tool
  • Craft knife
  • 110 Punch Down Tool
  • Loctite Super Glue

Step 2: Crimp the RJ45 Plug to the ethernet cable

Picture of Crimp the RJ45 Plug to the ethernet cable
...using the following wiring scheme:

1 White/Orange
2 Orange
3 White/Green
4 Blue
5 White/Blue
6 Green
7 White/Brown
8 Brown

Taken from the excellent Hardware Book: www.hardwarebook.net/cable/network/ethernet10basetstraightthru.html

Step 3: Punch down the other end to the RJ-45 keystone jacks

Picture of Punch down the other end to the RJ-45 keystone jacks
Take the other end of the cable, cut it to 9 inches and punch down the four pairs using the following wiring scheme:

  • Jack #1:

1 White/Orange to pin 1keystone jack
2 Orange to pin 2 keystone jack
3 White/Green to pin 3 keystone jack
6 Green to pin 6 keystone jack

  • Jack #2:

4 Blue to pin 2 keystone jack
5 White/Blue to pin 1 keystone jack
7 White/Brown to pin 3 keystone jack
8 Brown to pin 6 keystone jack

Once all the pairs are punched down, you can glue together side by side the two keystone jacks.

Step 4: Make one more splitter

Picture of Make one more splitter
...using the previous information so you end up having two splitters.

Step 5: Plug one splitter to the RJ45 wallplate

Picture of Plug one splitter to the RJ45 wallplate
... and plug the two computers to the splitter.

Step 6: Plug the other splitter to the patch panel

Picture of Plug the other splitter to the patch panel
...and plug two patch cords from the splitter to two free ethernet jacks from the switch. If your splitter connections are right the two leds "LINK" from the switch on which the patch cord are connected should turn on.
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MaurizioI1 month ago

Hi there,

I'm going to do this setup: 2 splitter at the start and at the end of ONE wire, in order to connect 2 devices with a single wire. It is possible? At one side there are connected 2 devices, on the other side is connected to the splitter and then to TWO different ports of my switch.

Thanks.

is it possible to use an Ethernet splitter to us on laptop and one line run to wireless router

i have tired it. it doesnt work well. actually in my experiment i made two ethernet wire from one. then the one i plug into the laptop and other one to the router.while laptop turned on both (laptop and router) doesnt get any internet access, barely laptop works well with internet access but not the router.

while laptop turned off router works well.

I wouldn't be surprised. I've never actually tried such a thing but I can't imagine why it wouldn't work. You might get a slower connection because you're basically splitting your internet in half though, presuming both your laptop and your router are on, though I don't really know how overall usage works when multiple sources are using it right from the same line.

I want to be able to split an Ethernet cable that has PoE to power 2 PoE devices and both fall well under the 15W max combined. Is this possible? So I can use the 2 wires carrying the 48VDC to power both devices, but that leaves me 6 wires to split the data. Can I do it hub style, like put the same 4 data wires to both devices?

aaronXtreme11 months ago

can u just hook it up directly to another wire.......i can't afford the connetctors

shalir1 year ago

splitter 2nd port not working plz help me. 1st & 2nd port use to internet purpus .not use to data & voice .

criggie1 year ago
You said 'This method is similar to PoE (Power over Ethernet) but instead of injecting DC, it is injecting another "data". ' which is kinda misleading.

Power over Ethernet is a negotiated protocol between the device and the switch, while still allowing the use of gigabit speeds using all 4 pairs.

You're thinking "Power over Cat5/6" which is where the spare pairs have 5 or 12 or 48 Volts and no negotiation. Don't ever plug anything gigabit into this.

These splitters do work, but are more likely to induce crosstalk between the two pairs of twisted pair inside the one run of cable. Yes I have used them as a last resort, but a local switch, or man-up and run some more cable is a far better way to go.

Cabling is almost always better than wireless ethernet.
jrdiver2 years ago
I'm just going to add this as a note: if you are trying to achieve faster speeds with Gigabit Ethernet, this is not going to work, as Gigabit uses all the pairs on its own, if you take away half of them it WILL limit you to 100mbps.
altso8882 years ago
using the following wiring scheme for T568B:

RJ45 Plug

1 White/Orange
2 Orange
3 White/Green
4 Blue
5 White/Blue
6 Green
7 White/Brown
8 Brown

Take the other end of the cable, cut it to 9 inches and punch down the four pairs using the following wiring scheme:
• Jack #1: T568B
1 White/Orange to pin 1keystone jack White/Orange
2 Orange to pin 2 keystone jack Orange
3 White/Green to pin 3 keystone jack White/Green
6 Green to pin 6 keystone jack Green
• Jack #2: T568B
4 Blue to pin 2 keystone jack (Orange)
5 White/Blue to pin 1 keystone jack (White/Orange)
7 White/Brown to pin 3 keystone jack (White/Green)
8 Brown to pin 6 keystone jack (Green)
Nova_Logic7 years ago
is there any way i could jsut buy this from walmart or somthin, i dont feel like doin any big complicated projects
Lol this isnt complicated.
Unless, of course, you don't have any of the required tools for this (which would cost more than making a few of these splitters).
I'll admit, it's not a "big complicated project", but there's no reason to pick at people.

A simpler option is to just buy a network hub, they're pretty cheap (often $20 or less). This is similar to an un-powered hub, though this is incompatible with PoE and Gigabit.
chrismake (author)  Groxx5 years ago
A network hub will work as well but will create a bottleneck. I guess each solution (network hub vs. splitters) has it's pros and cons.

As for DBLinuxLover's comment, what Instructable has he ever done ? 'nough said...
How does it create a bottleneck? 2 computers on a hub and 2 computers on this splitter still puts them on the same collision domain. In fact some hubs do exactly the same thing. Both layer 1 devices. Help me understand.
This device does not split the signal... it splits the cable. Normal ethernet on a Cat5 (4-pair) cable only uses half of the wires in the bundle (2 pairs). All this "splitter" does is redistribute signals so that one computer uses 2 pairs and the other computer uses the other two. They are on separate collision domains because they are still connected to two separate ports on the router... The analog to this setup is if you just had two ethernet cables running normally connecting two computers to a router.
Of Course! So simple. I should've read the instructable. Needless to say this won't work with gigabit networks then. Thanks for clearing that up.
It will, but you won't get gigabit speeds.
no, it wont.
No, not 'nough said... A lot of very experienced engineers read here but don't post. Their offering their expertise should be appreciated, not slammed. There's a reason that ethernet hubs have fallen out of favor compared to switches, and you have built a 2 port hub. They do create network bottlenecks and dropped packets and packet collisions. Your instructable is good for a fast 'n nasty, but to split a connection a switch is really the only way to go, especially when it comes to gaming where microseconds can be the difference between success and failure.
... Do they even sell hubs anymore? We tried to find some for our "Intro to Networking" class, to show bottlenecking and signal crossing... and nobody had any in stock anymore... Unless of course you guys are talking about switches...
I dug a hub out of the trash at work a few years ago. It was only 10 Mb, so that's why I assume it was tossed.

Engineers hoard the things at my new place of work. It's an easy tool to use to sniff network traffic.

I haven't seen hubs in stores for awhile either. For those who don't know, a hub shares the available bandwidth among all connections, while a switch typically has a backbone that is much faster than the ports so it can better insure that each connection gets full speed and doesn't have to share. In other words, two 100MB streams via a 100MB hub will get 50MB each. On a switch with a 1GB backbone inside they'd both see 100MB. Switches are so cheap now there is little reason for anyone to market a hub given their shortcomings.
Groxx jongscx5 years ago
They definitely do, though switches are primarily taking over because they're so cheap to make now. I think I remember finding an un-powered / power-optional hub a few years ago, too. As proof that they still exist, a quick search yielded one from Best Buy for $19. Though a switch with one more port was $22, and was 10/100, not just 10, so there's not much of a reason to go for that one in particular.
Most bottlenecks with home LANs occur at the cable/DSL/whatever modem. With the typical 100MB (or even 1GB) network two computers sharing a cable via a hub or switch will still be orders of magnitude faster than the ISP feed...typically. Unless you are doing a lot of heavy bandwidth stuff within your LAN that doesn't traverse the modem then worries about LAN bottlenecks are usually unwarranted. Unless WiFi is involved. That is an entirely different can of flying monkeys, but isn't relevant to sharing a cable via hub or switch.
philhartree4 years ago
Hi
I realise this is a couple of years old, but I wondered if I might ask you to check the text against the pictire.
Specifically, assuming the top left connector in the pic is pin 1, the colours don't match the text.
Your input would be greatly appreciated.
Regards, Phil
chrismake (author)  philhartree4 years ago
philhartree -> in the illustration of step 3, jack #1 will be on the right and jack #2 is in the left. The wiring is correct and match the text but it just depends on the type of keystone jack you have.
philhartree is correct the picture has blue in pin 1 and blue/white in pin 2 but your text says the opposite for jack 2
kdrayer3 years ago
this set up is for B configuation, is there an A?

Thanks
RodHq4 years ago
Hi, great instructable, but i have a question. If I want to do this, but I want three female ends instead of two, and no male ends, how should I wire the Keystone jack instead of the crimpable plug
chrismake (author)  RodHq4 years ago
They wiring is like this

1 White/Orange to pin 1
2 Orange to pin 2
3 White/Green to pin 3
6 Green to pin 6

4 Blue to pin 2
5 White/Blue to pin 1
7 White/Brown to pin 3
8 Brown to pin 6

The key is too keep the pairs together. Regards
Your set up is for B wiring configuration, do have the A version.

Thanks
jcasper663 years ago
DUUUH, I answered my own question. My 'sharer-splitter' adapters worked fine once I determined that BOTH keystone connectors and RJ45 plugs would use only the orange/green pairs. The router keystone connectors and or the DVD/TV cable box inputs must just use one half of the wires, those being the orange/green pairs.
The adapters allowed me to operate two separate devices off of a SINGLE Cat 5 cable as long as I had two free router outputs.
Thanks to all the comments as in the end they saved me from running an additional cable.
jcasper663 years ago
Is it possible to use a SINGLE Cat5 cable to connect two outputs of a cable TV router to a TV cable box AND a DVD (both needing separate ether-net inputs)??????????? I have no specs on any of the installed equipment but the concept of this thread seemed promising.

The simple solution of using TWO cables is not feasible due to access issues and the DVD/Cable TV converter are NOT wireless.

I tried simple homemade splitters at BOTH ends of known good SINGLE cable but only the side with the green and orange wires functions. The standard is 56B. I have probably oversimplified my solution but if there is some simple trick short of patch boxes/switches it might save me and other users some money. I can not open the cable box to see how the output and input keystone connectors are wired. Am also not a network guy but did work on vacuum tube TVs back in the 60s so I can follow a wiring diagram.

Reviewing other comments did not seem to help but since so many had similar issues with one side not working I am led to believe that what I am trying to do is just not that simple. The cable TV company is of no help either as they do not understand why I would not simply drag another cable through the wall.

Any help most appreciated.
I did all the steps but i cant seem to get it right. after i completed the splitter if i connect only one jack it doesn work but when i enter 2 jack only one works. i tried with the combination of colours you gave and the combination of the rjs i found on the existing set up
Klaudiuszm3 years ago
I like the idea :D. I haven't tried this, but in theory it would work.
giltech3 years ago
followed your instruction jack #1 works Jack #2 don't wok please advise thank you
jchusky3 years ago
i was wounding can you use both the ports at the same time .i have xbox 360 and a internet tv
Redion3 years ago
Well in my case I only have one ethernet outlet upstairs in the apartment building but I have 2 pcs. So i need a splitter!
soudeh3 years ago
i try it but jack 2 is not working
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