two network connections one cable?

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Wang191

[H]ard|Gawd
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Nov 30, 2000
Messages
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Is there some reason what I am trying to achieve does not work?

I have one cat5 cable running to a room. I want to send two independent ports to this room over the one cable...i cant run a second cable run at the moment.
So since 10/100 only uses two pr to send data I tried to take one jack and run two cables to it. Running one cable's T+,T-,R+,R- to the the normal pins and then another cable's T+,T-,R+,R- to the unused pins. I did this on both sides the same way.

I connected everything and it's a no go. What am i missing? I don't think I have any inconsistancys in my wiring but i'm testing continuity now.
 
If you trying to directly connect computers without a hub you need to wire the cables like this.

Cable 1a colors : Combined Cable colors Cable 1b colors

Green/White : Green/White : Orange/White
Green : Green : Orange
Orange/White : Orange/White : Green/White
Orange : Orange : Green

Cable 2a colors: Combined Cable colors : Cable 2b colors

Green/White : Blue/White : Orange/White
Green : Blue : Orange
Orange/White : Brown/White : Green/White
Orange : Brown : Green
 
Yeah that's what i tried. It does work. I found an error in one of my cables. One of the connectors didn't crip right.

Thank's for the confirmation on this, I was going to give up on it.
 
hokatichenci said:
10/100 Half duplex should work (as you noted), but I believe full duplex requires all 4 pair.
Click to expand...

Nope. I've seen a lot a 10/100 cards that don't even have pins 4,5,7, or 8 in the port, but they do full duplex just fine.
 
ryan_975 said:
Nope. I've seen a lot a 10/100 cards that don't even have pins 4,5,7, or 8 in the port, but they do full duplex just fine.
Click to expand...

*nods* I'm wrong then, not sure where I heard it but it was repeated enough among my friends that we all just assumed it and made the "standard" cables. Oh well :)
 
The problem might come from cross talk. Those other wires can help mitigate RFI/EMI.
 
Don't split your cable like that. It breaks the spec and will cause problems.

Just buy a switch for the room where you want the two connections and put the cable back they way it was with all four pairs being used.
 
Xipher said:
The problem might come from cross talk. Those other wires can help mitigate RFI/EMI.
Click to expand...

I've seen ethernet cables with 25 and 50 pairs that work just fine with the majority of them being used. The nature of UTP is to cancel out crosstalk.
 
Interfearance should not be an issue since the rx and tx in each of the two pr of cables is the same in regards to their twisted pair. Cross talk is a possibility but nothing that has caused any noticable collisions so far.

I have not changed anything on the main cable that comes to the room. It's still a standard rj45 jack on both ends. It's simply a dongle that connects two sets of cables through the use of 2pr from each and combines them at the jack to all 4 pairs in the main cable, then does the reverse on the other end.

Anyway, it's been working great and I don't have to worry about adding equipment to the room for now.
 
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