RJ45 splitter for Ethernet - possible ?

"P.Schuman" fired this volley in news:Ry8Hj.36354$ snipped-for-privacy@newssvr14.news.prodigy.net:

The advertiser did not say "Ethernet network connections", he said "network connections". Telephone systems are called "networks", also.

However, his presumption that its compact size will somehow enhance your internet experience is both stupid AND leads one to believe he thinks you CAN tee an ethernet connection.

LLoyd

I've had splitters like this in my tool box for the past decade, but have not actually implemented them.

Mine, are male on one side, and two female on the other.

Imagine that you plugged one into a wall jack at the location of a workstation, and another in the closet where your switch resides.

This would support two Ethernet or FastEthernet devices at the workstation location (e.g.: host, and network attached printer).

Each device would utilize two of the four pairs within the 8-wire (e.g.: Cat 5e) cable.

This is however, not an appropriate thing to do from a performance standpoint, and should not be standard practice.

If you were utilizing GigEthernet, I believe all four pairs are used to support a single device, and therefore splitting would not be an option.

Best Regards, News Reader

P.Schuman wrote:

ok - that pretty much answers the rest of your points

really - how ?

really - how ? considering that each Ethernet device normally expects pins 1/2 and 3/6 to be used ? So, you would have to fabricate a custom cable for each of these connections at each end and then plug that cable into your cable-sharing RJ45 splitters.. 1/2 = 1/2 3/6 = 3/4

1/2 = 5/6 3/6 = 7/8

You do not need to fabricate any custom cables, you just use a standard straight through cable for each connection. The splitters are used in pairs, one on each end of a single run of cable.

You are overlooking the key point.

The splitter is remapping pin placements.

Pins 1,2,3, and 6 on one of the female jacks are mapped to 1,2,3 and 6 on the male end, as you would expect.

The other female jack maps its pins 1,2,3, 6 to the other two wire pairs (pins 4,5,7 and 8) on the male end.

Best Regards, News Reader

P.Schuman wrote:

What he doesn't tell you is that you need TWO of these things. One at the wall plate and one at the back room hub.

You're better off simply dropping in a small $20 hub at the wall plate location.

AH HAH - YES.... IF the description mentions that the pins are re-mapped, then we have a solution - BUT only if deployed in pairs. I used to use them for piggyback of Phone + Ethernet + IBM 3270 on a single 8-wire RJ45 jack installed to each cubicle.

The original thread was basically using ONE of these "splitters" to just walk up to any RJ45 jack, plug in - and now have TWO jacks and TWO computers connected. OR - using a "splitter" to run an Ethernet cable between several computers, and basically T-connect them - as in the old coax days.

BTW - most of the eBay list> You are overlooking the key point.

The seller is not necessarily trying to deceive anyone.

Many products are promoted based on features, without any reference to how to implement the functionality.

The eBay post was probably like most news posts, incomplete.

Best Regards, News Reader

P.Schuman wrote:

News has the right answer. These splitters break out the 4 pairs into two sets of two. There is no problem with this in the ethernet standard (cat 5 can support 2 ethernet lans if they are 10/100) Don't do this with POTS phones unless you can live with the errors when the phone rings. It will not work with gigabit LAN, that needs all 4 pairs.

BTW I am doing this at my house and it works fine. (no packet errors)

The ones I see on eBay are female on both sides.

That would be true if they split the pairs, but the descriptions of the ones on eBay all say "parallel wiring", which implies that they don't. I can't imagine that they are of any practical use whatsoever for Ethernet.

-Larry Jones

You don't get to be Mom if you can't fix everything just right. -- Calvin

In comp.dcom.cabling P.Schuman wrote in part:

Yes, I remember a passive circuit for 10baseT that might work under lucky conditions (short run, short patches). No guarantees of any kind (including router port-burnout). I doubt it would work at 100, and hubs are too cheap for passive to be worth the risk.

-- Robert

The genders really aren't relevant, as long as the four pairs are fanned out correctly. The version I have is usable when you are accessing the cable run via a wall jack. If I had access to the raw end of the cable, then I would want the genders per the product the guy is selling.

Your interpretation of his use of the term "parallel wiring" may be correct. However, it may also be that the seller has a poor understanding of the english language, or even the functionality of the product he is selling.

I'm not condoning the use of splitters, I'm only suggesting that a legitimate product exists, that maybe the product he is selling is an example of the legit product, and that maybe he has represented its use incorrectly.

I'd be interested in reading the seller's e-bay description, if somebody wanted to post it here.

Best Regards, News Reader

snipped-for-privacy@siemens.com wrote:

Since 10Base-T and 100Base-TX were both designed to coexist with phone lines in the same cable, that shouldn't be a problem.

-Larry Jones

Start tying the sheets together. We'll go out the window. -- Calvin

The product I have had in my toolbox for the past decade can be found at:

I have not reviewed the info at this link, and have not confirmed what Category they are.

They are probably Cat 3 (suitable for Ethernet only).

Maybe they have a Cat 5e version suitable for FastEthernet, but you would have to research that for yourself.

Best Regards, News Reader

News Reader wrote:

These things exist. Here is a sample pin layout:

recommended but will work on 2-pair varieties of Ethernet - 10BASE-T and 100BASE-TX. Will not work on Gigabit Ethernet or higher though. And no, they don't create two Ethernet network ports, they just simply create two two-pair patch cords if you will under the sheath of a single four wire category cable

Possible and advisable are two different things.

A telephone ringing signal is an 88v 20Hz A.C. signal superimposed on

48v nominal D.C. supervisory voltage.

Hardly low voltage, and not appropriate for sharing a Cat 5e cable run with data.

Readers should observe gfretwell's caution.

Best Regards, News Reader

snipped-for-privacy@siemens.com wrote:

Might want to check your system clock.

Your last post came in about an hour early.

:>)

Best Regards, News Reader

snipped-for-privacy@aol.com wrote:

Maybe BICSI has changed their opinion but that was what I heard when I was in school. I know it works but it is not recomended

The only way this could actually work is if you used one on both ends and each socket was wired to use seperate pairs. Since 10/100 ethernet only really uses 2 of the 4 pairs in a cable in theroy this would work. but again you have to have one on each end. It will not work on gigabit ethernet.

Adair