There’s no way this works

[JordB]

Ethernet splitters are all over the internet, but aren’t they just a scam to steal from the uninformed? Well, mostly. But with a little knowledge of the history of networking, you really CAN run two devices over a single network cable!

 

Buy a TP-Link 5 Port Gigabit Ethernet Switch: https://lmg.gg/lp5ev

Buy a TP-Link 5 Port Ethernet Switch: https://lmg.gg/3F5f5

 

Purchases made through some store links may provide some compensation to Linus Media Group.

 

EDIT:  

Since reading comments from you beautiful people, we want clarify a couple things. First, the fact that ethernet is digital (as opposed to analog) is not the reason that these splitters don't work. In fact, some digital signals can be split, such as I2C, DTV, or ARINC.

 

Many other commenters are suggesting using these splitters as passive hubs, and in the past that could have been a possibility- but these splitters aren't wired correctly for that either. The transmission pins on the sending device needed to connect to the receiving pins on the other end. Simply wiring the pin 1 to pin 1, 2 to 2, etc. as we see here does not work. 

 

While some of those old / deprecated features of the earlier ethernet standards could have enabled devices similar to these to work with very old network adapters, few, if any modern network adapters support these features and ultimately the wiring diagrams presented on the product page don't suggest that the seller intends customers to use them in that way. 

 

Our apologies for not making all this obvious in the video!

[Ubersonic]

Genuinely disappointed at LTT for such a **** tier video. The vast majority of the Amazon splitters work flawlessly and are in no way scams, the bad reviews/complaints are just by technological illiterates who didn't realise you need to use them in pairs (with one at the outlet and one at the patch panel) and they're designed for splitting an 8pin gigabit connection into two 4pin 10/100 connections over a single 4 pair cable.

[TylerD321]

2 minutes ago, Ubersonic said:

Genuinely disappointed at LTT for such a **** tier video. The vast majority of the Amazon splitters work flawlessly and are in no way scams, the bad reviews/complaints are just by technological illiterates who didn't realise you need to use them in pairs (with one at the outlet and one at the patch panel) and they're designed for splitting an 8pin gigabit connection into two 4pin 10/100 connections over a single 4 pair cable.

Not everyone that watches LTT is a technological genius. Why shouldn’t they create a video explaining how it works? 

[enchev]

So, in the end, what can such headphone-like splitter be useful for? Can the split signal be used for monitoring/spying the communication between the other 2 connected devices?

[OhYou_]

40 minutes ago, Ubersonic said:

Genuinely disappointed at LTT for such a **** tier video. The vast majority of the Amazon splitters work flawlessly and are in no way scams, the bad reviews/complaints are just by technological illiterates who didn't realise you need to use them in pairs (with one at the outlet and one at the patch panel) and they're designed for splitting an 8pin gigabit connection into two 4pin 10/100 connections over a single 4 pair cable.

if thats how it works then neat.
 

however, you can just literally split the ethernet signal to two devices as well. They will negotiate it and rely on CSMA/CD like a hub would. it will probably fall back to 100mbps though. It is popular in my field to do this to literally wiretap a device for diagnosing issues.

[iPolymer]

50 minutes ago, Ubersonic said:

Genuinely disappointed at LTT for such a **** tier video. The vast majority of the Amazon splitters work flawlessly and are in no way scams, the bad reviews/complaints are just by technological illiterates who didn't realise you need to use them in pairs (with one at the outlet and one at the patch panel) and they're designed for splitting an 8pin gigabit connection into two 4pin 10/100 connections over a single 4 pair cable.

LTT has 313 videos a year; not all of them are going to be good. 

[manikyath]

the "splitting an ethernet jack" thing happens a lot when IT guys have to pass POTS lines trough an office's ethernet infrastructure, because a CAT5e cable is basicly the same as 4 POTS lines.

 

past that, the breakout box thingy *can* theoretically work, but iirc it *really* confuses auto-crossover devices (in theory RX goes to TX, but switches do this internally.. but everything is auto crossover these days. hence the two different standards for wire order. same standard on both sides is a 'straight' cable, and different is a 'crossover' cable.. which basicly got replaced by auto crossover, meaning the ethernet device itself can switch those lines as needed.)

 

i'm pretty sure if you set the switch, and two endpoints up correctly, they'll work.. it's just a weird artifact of ethernet history that was surpassed by "the logical solution". i'm pretty sure you cant even have the switch shown turn *off* auto crossover.

[kevincox]

The thing is that these should mostly work. Most of the video is plain wrong. Ethernet has collision detection so you can literally wire up multiple devices fully-connected like this and they will communicate. Analog vs digital isn't really relevant here. This is referred to as a (passive) hub. As opposed to a switch which has a routing cache so that it can send the packets to the correct device a hub will send all packets to all devices. However devices ignore packets not addressed to them so no harm done (other than wasted airtime). When the video talks about devices responding that is done at a much higher layer. So the devices that ignore the packet won't respond so there is no issue.

 

However there is one glaring issue here, it makes no sense to split the cable and put both wires into the same switch. That won't give you more bandwidth and in fact is likely the source of most of your problems. The switch may have loop detection and when it detected a loop on those two ports it might have shut them down, leading to no network connection. So those wiring diagrams from the product listings are complete bogus, which is strange for a product that should otherwise work. Instead of splitting into two ports of the switch you should be able to just plug the single wire directly into a single port and have a working connection.

 

However even in that case the two other devices should have been able to communicate (as long as they support auto-crossover which IIRC is required for gigabit and above devices). However Windows may have been showing that there was no connection because there is no DHCP server on that two-device network to assign IP addresses. (However IPv6 link-local addressing should work fine.)

 

In fact this setup can be fairly effective. If both devices transmit at the same time there will be an awful backoff and retransmit process which will greatly impact your upload speed if both devices are trying to communicate at the same time. However download speed should actually be fairly good as the switch will just blast packets at its full rate. So either device can get the full bandwidth at a time (or they can share as needed).

 

But at the end of the day there is a reason that you don't see hubs around anymore. When you can buy a switch for $7 it is probably a better option than a hub for most use cases. So I can agree with the conclusion of the video, if not the rationale.

[Snapstromegon]

@OhYou_ is right here. I also commented under the video that using just one of the splitters should've worked due to CSMA/CD and Ethernet's backwards compatibility to it. Was this tested and just didn't make the cut, or is this something that was ignored completely?

 

The main problem in my opinion is connecting to two ports of the switch, which will confuse every reasonable switch / the switch will detect that loop and just drop those connections.

 

Edit:
Funny thing, I just checked and there is a Techquickie that describes what a Hub is and why the thing in the video should work like it's explained here: 

 

[kokosnh]

How did they even find these RJ-45 Y splitters, that don't split the 4 pairs, on 2 pairs etch, so you get 2 x 100 Mbps on one Ethernet wire. 
We use them (the good ones) all the time, if we have old cabling, to for example, run 2 VLANS on one cable, for 2 different devices (PC and printers)

These that they have, I believe are used for sniffing traffic, and probably are made exactly for it (but you can't exactly market it that way) and work similar to a passive hub. 
But well, you could also use it to split a analog phones RJ-11 etc. (there are actually lots of application for it)

And as mentioned above, you can get it to work on normal flat home network (without fancy port security, loop detection  etc.), because it will work similar how passive hub did.

 

Ps. and yes, if you use that Y splitters as passive HUB, you need only one (on the devices side), not a pair of them...  

They just made a loop on the switch side, with that Y splitter when they connected it to the switch by 2 ports, so best case scenario is a broadcast storm (and if the switch is powerful enough, and the network have very little devices, it can actually work, not great, but still). 

[apple010]

I think the structure of this video led to a lot of confusion. Omitting comparison with passive hubs made the video simpler to newbies, but made everyone who was familiar with these concepts already very confused (this is me).

Creating a switching loop at 0:50 and 1:40 only made my brain hurt more haha (they are basically plugging the switch into itself).

And then the icing on the cake, advertising a drop-shipping company!! yay!!!

 

Back on hubs though, since that seems like the hot topic of discussion. I don't have experience with this but I am massively doubting that a real passive hub is wired like this splitter device is.

In a hub, when a computer sends a packet on it's TX pair, doesn't that packet needs to go out of the RX pair on all the other hub ports? If I'm thinking about that right this won't happen with this splitter here. CSMA/CD is irrelevant here because packets aren't going down the right pairs anyways.

In a passive hub you need at the very least diodes and capacitors sitting in between the ports.

 

Now with auto crossover, this could be accounted for, but then I don't think both computers would be able to communicate with the switch. They would be able to communicate with each other, but then only one NIC would be in the right mode to communicate with the switch.

[apple010]

51 minutes ago, enchev said:

So, in the end, what can such headphone-like splitter be useful for? Can the split signal be used for monitoring/spying the communication between the other 2 connected devices?

My guess is that the primary use for devices like this (where all 8 wires are split 1 to 2) are for signal control devices that use rj45 ports, but do not use ethernet/networking.
Instead they are being advertised on amazon as an ethernet splitter, but in small text saying you can only use one computer at a time lol.
Most splitters on amazon seem to be splitting the pairs between the ports like the one they made in the video.

[djenson]

This video felt like a techquicky, adapted to a main channel video and the scriptwriter only had 30 minutes to write up the script 

(essentially) plugging the switch into itself (which would make sense for your idea initially, but then you could have gone on to how this is essentially a ethernet hub and how this might/mightnot work)

 

After the 100Mb 2 pair example, you talk about using a switch as its faster, but then do a cost comparison to a 100Mb switch?  What. 

 

Digital cannot use splitters? 

Then the cherry on top as mentioned above, a dropping shipping website thing? Nothing wrong with that per say, but really? 


 

[BabaGanuche]

14 minutes ago, apple010 said:

In a passive hub you need at the very least diodes and capacitors sitting in between the ports.

No a passive hub just connects the wires together. You can build a passive hub with just wire nuts.

[BachChain]

The whole video, I just kept thinking about how ethernet was specifically designed to have multiple clients just spliced into a single coax cable

[themrsbusta]

One question: if it was half of pins to each jack, wouldn't work but in "Half Duplex" mode instead of conflict?

[Nystemy]

To be fair. Keeping track of Tx and Rx pairs isn't super critical in practice for 100baseT. Since a lot of switches do notice this and swap their behavior accordingly. _{(Ie, Auto MDI-X)}

Some Ethernet drivers have also started supporting polarity correction as well.

 

There is 384 ways to wire a 8P8C _("RJ45") connector and still keep the pairs intact. But in practice, only 2 of these ways are allowed. Or 32 if both Ethernet controllers has polarity correction. However, some gigabit and above controllers can also handle swapped pair as well.

 

So in practice it won't be too many more years before one only have to ensure that each pair position has a pair wired to it. _{(It doesn't matter if pair 1 technically is on pair 2, or 3, Ethernet controllers will just shrug and auto negotiate through one's mess.)}

 

However, I would love if Ethernet controller started supporting splitting a port in half and get two ports at half speed.

Ie, split a 1 Gb/s port into two 500 Mb/s ones. Gigabit does send 500 Mb/s per pair, but the drivers just don't want to do it unless they have 4 pairs of connectivity between them. Same thing for 2.5 Gb/s ports being split to two 1.25 Gb/s ones, or 5 Gb/s to two 2.5 Gb/s, or 10 to two 5s.

 

From an electrical and signal integrity standpoint there is no issues.

It is all just the standard being a bit strict in wanting 4 pairs for anything more than 100 Mb/s.

 

I can see quite a lot of practical uses for situations where one needs more ports, but want more than just 100 Mb/s. After all, half a gigabit port is a lot better.

 

Another advantage of running on half a port is better resilience. If a cable gets damaged, one won't loose the connection but rather just drop in speed. _{(though, here one would preferably be able to loose any arbitrary pair and still work. Currently this is almost the case as long as pair 2 and 3 are intact. A gigabit or above connection will stumble back to 100 Mb/s if pair 1 or 4 breaks, but if 2 or 3 breaks the connection is lost...)}

[Kandra]

At 1:42 didn't they make a loop between the blue and green wires coming out of the switch? since the ports on the splitter are wired together?

[dogwitch]

the average internet speed in usa is wrong.

is highly cherry pick and mis used data points

[Senzelian]

18 hours ago, Ubersonic said:

Genuinely disappointed at LTT for such a **** tier video.

Genuinely disappointed at you for such a **** tier comment.

 

17 hours ago, iPolymer said:

LTT has 313 videos a year; not all of them are going to be good. 

This was a good one tho.

 

[kokosnh]

21 hours ago, JordB said:

Many other commenters are suggesting using these splitters as passive hubs, and in the past that could have been a possibility- but these splitters aren't wired correctly for that either. The transmission pins on the sending device needed to connect to the receiving pins on the other end. Simply wiring the pin 1 to pin 1, 2 to 2, etc. as we see here does not work. 

There is this thing called cable...  

And I don't want to even start with the fact, that you skipped, that most of those splitters, are just like the one you DIY on the video, and work just fine. 

 

15 hours ago, Kandra said:

didn't they make a loop between the blue and green wires coming out of the switch?

yes they did, and I would want to know if the ports were disabled by loop detection, or did they bring the entire network down, and that's why it didn't work. 

 

 

[Ubersonic]

On 6/8/2023 at 6:05 PM, TylerD321 said:

Not everyone that watches LTT is a technological genius. Why shouldn’t they create a video explaining how it works? 

And if they'd done that it would have been great, however the first thirty seconds of the video was just a mixture of misinformation and lies to try and hook people 

 

Also basic hardware knowledge doesn't make somebody a technological genius.

[wanderingfool2]

On 6/8/2023 at 10:02 AM, Ubersonic said:

Genuinely disappointed at LTT for such a **** tier video. The vast majority of the Amazon splitters work flawlessly and are in no way scams, the bad reviews/complaints are just by technological illiterates who didn't realise you need to use them in pairs (with one at the outlet and one at the patch panel) and they're designed for splitting an 8pin gigabit connection into two 4pin 10/100 connections over a single 4 pair cable.

I was curious, and typed in "ethernet splitter" and the first 3 options I got were the garbage ones where you can't use 2 devices at once, the next was effectively a powered switch and the last was one where the documentation does seem to fit.

 

So while you say "vast majority" works flawlessly keep in mind that the first results for some are garbage; which then yea it's important to have a video like this because theres a lot of people who would see it and not understand.

 

 

In relation to this video though, I've used this trick once before when contracts one time or another cemented the conduit pipe.  I couldn't use a switch due to needing the traffic separated due to a few security requirements...I mean in theory I could have done VLAN stuff to separate them...but then that would have required 2 more managed switches.  This was a good alternative, fast enough, cheap (I built my own), and it worked.

 

Sometimes you just can't use a switch, also if the switch consumes lets say 1W-5W of power it still has a cost of $1-5/year.  Just plugging in devices like that can lead to larger powerbills overtime as you get more and more phantom draws in your house

[MatazaNZ]

This video has been quite handy very recently. We have another company putting in a PA system. Nothing out of the ordinary. Except their gear uses PoE, and they are trying to put in these splitters where only 1 link exists. Except on those links they are putting splitters on have WiFi access points on the other end too. ALso using PoE. So they are trying to put 2x PoE injectors -> Splitter -> Patch panel -> Splitter -> 2x PoE consumers. Before this video, I suspected that would not work as they intend, and that has been confirmed. At best, we have our APs running at 100Mbps, at worst, they are causing irreparable damage. 

 

So now I have some ammo to go into a meeting tomorrow with.

[YellowJersey]

Had to make this meme for this post.