How-to make your own Ethernet "splitter"

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.

Step 1 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

Comments

[Nova_Logic]

is there any way i could jsut buy this from walmart or somthin, i dont feel like doin any big complicated projects

[DBLinuxLover]

Lol this isnt complicated.

[Groxx]

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]

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...

[meenzal]

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.

[mgalyean]

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.

[jongscx]

... 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...

[kill-a-watt]

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.

[mgalyean]

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]

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.

[Luistheguitarist]

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.

[jongscx]

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.

[Luistheguitarist]

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.

[jongscx]

no, it wont.

[jchusky]

i was wounding can you use both the ports at the same time .i have xbox 360 and a internet tv

[Redion]

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!

[soudeh]

i try it but jack 2 is not working

[mahinder]

There are different configurations for  Ethernet splitters, which depends on the objective of the usage for example an rj45 splitter used for data- data splitting different  from that of data- voice splitter and which is again different from the voice - voice splitter. The user must be aware of this while buying an ethernet splitter.

[mickad27]

Would this work with 1 ethernet and 1 USB connection? Like instead of the 2nd ethernet port, I would put on a USB port. Or would there be cross-talk?

[rrrmanion]

am i right in thinking packet collisions are more common with this setup?

[smitdesai]

Is this work if 3 pc connected to single internet connection ??

[chrismake]

You need a 3 ports router on which you connect you 3 PCs.

[rrrmanion]

or, connect a hub to the modem router, or if you get internet access through a modem on one of the computers, set that up to share it's network connection, then hook up a switch to that

[jefftoshey]

I also cant get the two computers connected simultaneously to the switch. only one can connect to the internet. kindly assist

[chrismake]

These splitters don't connect directly to the switch but to the patch panel.

[RodHq]

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]

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

[leethebee]

Hello Chrismake,

I have attempted to do this to connect 2 computers to one modem, but it is not working.  Only the oranges and greens are working.  I'd like to use this concept to run 1 ethernet cable to my bedroom (from the basement) to connect 2 computers to the internet.  Am I missing something or a step?  I didn't really understand step 6...

[chrismake]

leethebee: you must be confused with "modem" and "patch panel". A patch panel is as shown in step6. Thanks.

[philhartree]

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]

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.

[nzsammy]

Its main aim, is on a 10/100mb Lan (which only uses two pairs) utilizing the other two pairs in the cable for a second Ethernet device. This is for cable only and will not work by trying to run two pc's off one switch port, each pc must use its own port, but two pc's can share one cable. The same can't be said for Giga-Bit (1000mb), This uses all four pairs so using a splitter would force the NIC to 100mb.

[pierlinn_buenvenida]

help me --- what is the main purpose of that spliter its use in 2 pc or its for hub or rounter thank you

[Eegras]

If you're running Gigabit (like I am) this trick won't work.  10/100 connections only use 2 pairs (4 wires) which allows this hack to work.  Gigabit uses 4 pairs (all 8 wires).

[tyler9613]

I knew it was possible!

Is performance reduced at all?

And where do you get your keystone jacks? They look really nice.

[wokwithme]

Performance should be fine for 100Mb which uses just 4 out of 8 wires. Not for 1000Mb or 1Gb since that uses all 8 wires.

[rahulait]

which standard r u using???
568A or 568B ?
then the connections might change....

[wokwithme]

I'm not original Poster. I have build my own with matching Data Jacks sets and Just use Standard Cables. You can buy the Ethernet "Splitter" Jack Kit on Ebay (I call it a  "Sharer," instead for less confusion).  Make sure to get the special ones that come as a set. I think there's only one Seller that has them in the NA.
Yes the 568A and 568B are different connections, but that's on the cable or termination on the jacks. All Jacks are built the same hence "structured cabling." You decide which wires are for what. In this case, you disregard the 568A or 568B standard when you configure the Splitter/Sharer.

[rahulait]

so is it that the switch sends data to all the 8 lines we have in CAT5, because only then its possible otherwise the output of the switch will not match with the kind of input we want for the two jacks, i.e. both having sending and receiving lines....... but that's creating some confusion how is it going to work... all 8 lines having access to input , or some particular format is there,,, can you help me on that???

[wokwithme]

You are using 4 wires per connections. You will be using 2 ports from the switch or router. The Switch/router will run fine on 10/100MBps with 4 wires. The CAT5/CAT6 cable in the middle and between the 2 Jack Splitter/Sharers will use standard EIA/TIA 568A/568B wiring.

We're borrowing the Unused 4 wires to run the 2nd 10/100MB Ethernet connection. PIN number 1,2,3, and 6 are the regular 10/100 on the 1st connection. We are borrowing the unused PIN number 4,5,7, and 8 to run the 2nd connection on the 8 wires on the Main(middle) cable. Then we swap back the wires for PIN 4,5,7, 8 to PIN 1,2,3, 6 for the 2nd jack which connects to the 2nd Device/Node because all Nodes and Devices will only sync with  PIN 1,2,3, 6 on their RJ45 port to get 10/100MBps Ethernet connection.