Old 10-08-2009   #1
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Use 1 ethernet cable for 2 devices

Hi,
I'm trying to connect two devices to a single ethernet cable. My router has enough ports, but it would be much easier to use a single cable. My question is, is this possible and what would I need? Also, will I maintain gigabit speed for the devices? (I mean seperately, I will not use them at the same time). Thanks.

Daan
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Old 10-08-2009   #2
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Re: Use 1 ethernet cable for 2 devices

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Originally Posted by daan_odi_ View Post
Hi,
I'm trying to connect two devices to a single ethernet cable. My router has enough ports, but it would be much easier to use a single cable. My question is, is this possible and what would I need? Also, will I maintain gigabit speed for the devices? (I mean seperately, I will not use them at the same time). Thanks.

Daan
Short answer answer....No....Each has to connect to the router...but since you didn't mention what the devices are it will be hard to know what your referring to.....
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Old 10-08-2009   #3
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Re: Use 1 ethernet cable for 2 devices

You cannot connect an Ethernet cable to more than two devices - one at each end.

If you have two devices close to each other and the router is some distance away, there are two ways to connect your devices:

1. Run an Ethernet cable from each device to the router. I assume this is what you want to avoid.

2. Buy an Ethernet switch.
4-5 port 10/100 Ethernet switches are cheap these days but GigaBit switches are more expensive.
Buy two short Ethernet (patch) cables.
Put the switch near your two devices; it will need to be plugged in to a power outlet.
Run a cable from the switch to the router.
Run two (short) cables from the switch to the two devices.

You'll have to decide whether option #2 is attractive to you.
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Old 10-08-2009   #4
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Re: Use 1 ethernet cable for 2 devices

Hmm, I hate to disagree here because I don't like to juryrig networks. But, having seen really rigged things, yes it is possible, although I would never recommend such a thing.

From your router run the ethernet cable.

At the end where your devices, at the end of the cable, plug the cable into a coupler

Plug a splitter into the coupler and run 2 ethernet cables from the splitter to your devices.

If you want the devices to work at the same time you will need to purchase an additional coupler and splitter to wire the router side as well so that you have 2 full sets of wires going, in which case it would just be easier to run 2 ethernet cables the entire length in the first place.
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Old 10-08-2009   #5
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Re: Use 1 ethernet cable for 2 devices

The solution explained by brokenbuga will not support Gigabit Ethernet, since only two wire pairs will be available per connection, but it could support Fast Ethernet.

It sounds too clunky and non-standard to me, but it might be cheaper than the switch solution.
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Old 11-08-2009   #6
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Re: Use 1 ethernet cable for 2 devices

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The solution explained by brokenbuga will not support Gigabit Ethernet, since only two wire pairs will be available per connection, but it could support Fast Ethernet.

It sounds too clunky and non-standard to me, but it might be cheaper than the switch solution.
The use of splitters will only truly support 10 MB. I recall doing couplers to take a Cat5 cable run (100 MB) and break it down into basically 2 Cat3 connections which support only 10 MB.

The valid choices are exactly what has already been stated:

1) Run a second cable which is your BESToption (in my opinion)

2) Buy a second switch or hub (a switch would be my choice if going this route) to put at the end of the cable run, then use short patch cords to plug from the switch into each device.
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Old 11-08-2009   #7
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Re: Use 1 ethernet cable for 2 devices

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The use of splitters will only truly support 10 MB. I recall doing couplers to take a Cat5 cable run (100 MB) and break it down into basically 2 Cat3 connections which support only 10 MB.
That is what DrageMester said, Fast Ethernet is 10MB Ethernet.

There are couplers that are Cat5e certified, using couplers is fine to extend patch cable runs. The use of splitters however is a bad thing indeed. The OP was looking for an alternative to a hardware solution, for whatever reason, one is available and we can all agree it is a poor one.
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Old 11-08-2009   #8
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Re: Use 1 ethernet cable for 2 devices

In order to avoid (or increase?) confusion:

Ethernet = 10 Megabit per second.
Predominant standard is 10Base-T over Category 3 or better cable

Fast Ethernet = 100 Megabit per second.
Predominant standard is 100Base-TX over Category 5 or better cable

GigaBit Ethernet = 1000 Megabit per second.
Predominant standard is 1000Base-T over Category 5e or better cable
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Old 11-08-2009   #9
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Re: Use 1 ethernet cable for 2 devices

Thanks a lot for all your responses.
All right, here you see what I have in mind. Will I, using this, maintain at least fast ethernet speed? (and not below that)

Daan
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Old 11-08-2009   #10
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Re: Use 1 ethernet cable for 2 devices

The most I would count on being able to get through that splitter would be 10 MB. 100 MB, in my opinion would not be reliable.
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Old 11-08-2009   #11
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Re: Use 1 ethernet cable for 2 devices

What seems to cause the confusion is the misuse of (B)ytes for (b)its. As DrageMester correctly points out, network speeds are rated in bits, not Bytes.

So, In simple terms:

Ethernet = 1.25MB

Fast Ethernet = 12.5MB

Gig Ethernet = 125MB

As already pointed out, Gig Ethernet will not be possible with that arrangement. I figured you weren't too concerned with speed in the first place if you were asking for this kind of option.

Do you live in your own home or are you in shared housing of some sort? I ask because if you are in your own home, there is one other option I can think of, although it may be cost prohibitive. There is ethernet over AC power line as well. It would be a more elegant solution. Would save you the trouble of running a cable.

Just throwing out ideas at this point. Don't mind me.
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Old 11-08-2009   #12
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Re: Use 1 ethernet cable for 2 devices

With all due respect- oh forget it...

I am a network engineer as well as and electrical engineer, this may be the ONLY topic I can speak to with any intelligence or cred.

The MOST important question, that I don't think was asked is- What cable are you using, and will each end be required to plug into a standard wall jack before you connect it to your equipment?

The 100base-TX standard uses ONLY 2 transmit/ receive pairs (4 conductors). The additional wires provide absolutely no additional value at all. I think some of you are confusing this with trying to run 100MB over cat 3 or cat 4 cable... which you can do too... however, you have to terminate your connectors using the 100base-TX4 standard, which requires the use of all eight wires. Even then, it STILL only uses one transmit and one receive pair. The other two pairs negotiate direction as needed using 8B6T code and the data is sent then over the 3 pairs using 3-level pulse-amplitude modulation. It is basically the same reason gigbit ethernet works over cat 5.

So, that basically means you will have absolutely no problems running this setup over cat5 or cat5e cabling. No, you will not have ANY problems with near-line crosstalk or EMI from the other device... unless the other device is a non-standard device that uses one pair for both transmit and receive and another to carry 48 volt ring voltage! :-)

The only time I have seen this as a problem, is when a buddy of mine used his 8 conductor wire (Cat5) in his house to run Ethernet (2 pair), Phone (one pair), and a mono speaker connection (1 pair... too many). He had these on both sides of each room, thinking he was clever. He was dumbfounded to find that when he was cranking up the sounds, he had file copy and network problems... (it was the interference from the speaker wire).

That said, the connector you show will not work. You need to spilt BOTH sides of the cable. You basically are going to spilt it up into two sets of two pairs.

CHECK THIS: if you have wall plates where your cables plug in on each side, you will need to open them and make sure they have all 8 wires punched down on BOTH sides. I have seen some morons back in the old days actually snip off the brown and blue color pairs before punching down the wall plate... nice huh? You could use a cable mapper too.

Ok, to make a short story even longer, here is what you do...
Cut the end off the cable that is going into your router- and cut the end off the cable at the other end (where you want the devices).

Slice the shielding down about a foot. Terminate both ends normally for 100baseTX using just two pair. (pins 1 &3, 2 & 6 using the orange and green pairs)

Wires to connect for your first cable (at each end):
(Pin one is always the left-most pin if the flat side of the connector is facing you and the copper pins are facing away from you.)

Pin Color
1 white and orange
2 orange
3 white and green
4 UNUSED
5 UNUSED
6 green
7 UNUSED
8 UNUSED

Wires to connect for your "second" cable (at each end):

1 white and blue
2 blue
3 white and brown
4 UNUSED
5 UNUSED
6 brown
7 UNUSED
8 UNUSED

If you need to extend the cables further, use a standard 8 connector straight-through coupler and regular network cable for each end. Don't try to split the wire down 20 feet, as you will lose your twist, and could have problems with florescent light interference or something like that.

Final Note: Do not attempt to piggy back or wire into the back of your wall plates to create the extra cable without disconnecting the wires from the wall jack- otherwise, if someone plugged in a device that provided power over those spare wires, you could blow your network card.

Have a good time!

Captain Clam...
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Old 11-08-2009   #13
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Re: Use 1 ethernet cable for 2 devices

I apologize for not reading your last post more clearly...

You said you will not have the devices on at the same time...
If they will actually be disconnected from power, then yes, you can do it, and it WILL SUPPORT GIGABIT speed... and YES, depending on the internal connectivity, the device you have pictured COULD work.

If the device you show, is actually just a pair splitter, it will work (read on for warnings) because it is simply creating equipotential points of the primary connector at each duplicate connector.

Now, if one of those the Z-end (non-router end) devices support wake-on LAN or other standards than I think you might be in trouble... unless you physically disconnect the wire, or remove power to the device completely while the other is being used.

All theory aside- a cheap switch is your best bet- without a doubt! However, it is fun to think about how to do it without a trip to best buy or Ebay.
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Old 11-08-2009   #14
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Re: Use 1 ethernet cable for 2 devices

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Originally Posted by brokenbuga View Post
What seems to cause the confusion is the misuse of (B)ytes for (b)its. As DrageMester correctly points out, network speeds are rated in bits, not Bytes.

So, In simple terms:

Ethernet = 1.25MB

Fast Ethernet = 12.5MB

Gig Ethernet = 125MB

As already pointed out, Gig Ethernet will not be possible with that arrangement. I figured you weren't too concerned with speed in the first place if you were asking for this kind of option.

Do you live in your own home or are you in shared housing of some sort? I ask because if you are in your own home, there is one other option I can think of, although it may be cost prohibitive. There is ethernet over AC power line as well. It would be a more elegant solution. Would save you the trouble of running a cable.

Just throwing out ideas at this point. Don't mind me.
If you use this option- be careful that both endpoints are on the same side of the electrical bus bars [that the circuit breakers for the receptacles on each end are in the same row in the breaker box]. I have not found one of these Network over AC device pairs yet that are able to jump from one side of circuit breakers to the other.
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Old 12-08-2009   #15
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Re: Use 1 ethernet cable for 2 devices

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Originally Posted by DrageMester View Post
It sounds too clunky and non-standard to me, but it might be cheaper than the switch solution.
I was wrong!

Calculating cost...

The clunky solution:
Splitter (Amazon): $14.24
Coupler (Newegg): $6.99
2 patch cables: xxx

The standard solution:
Switch 10/100 5-port (Newegg): $12.99 (a $9.99 switch is also available)
2 patch cables: xxx

The clunky solution is actually more expensive than the standard solution, probably because switches are mass produced and splitters/couplers are specialty products.

The biggest drawback of the standard solution with a switch is that it requires power.
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Old 12-08-2009   #16
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Re: Use 1 ethernet cable for 2 devices

Thanks again for all your solutions.
Having read your suggestions I presume buying a switch will be the safest and perhaps best method - and damn cheap. I'm thinking of placing the switch near my devices, with one 7m. cable connecting it to my router. Would that cause no problems?
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Old 12-08-2009   #17
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Re: Use 1 ethernet cable for 2 devices

Thanks again for all your solutions.
Having read your suggestions I presume buying a switch will be the safest and perhaps best method - and damn cheap. I'm thinking of placing the switch near my devices, with one 7m. cable connecting it to my router. Would that cause no problems?

Quote:
The biggest drawback of the standard solution with a switch is that it requires power.
Do you mean in terms of electricity?
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Old 12-08-2009   #18
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Re: Use 1 ethernet cable for 2 devices

Sorry for the double post, look at the last one...
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Old 12-08-2009   #19
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Re: Use 1 ethernet cable for 2 devices

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Originally Posted by daan_odi_ View Post
I presume buying a switch will be the safest and perhaps best method - and damn cheap. I'm thinking of placing the switch near my devices, with one 7m. cable connecting it to my router. Would that cause no problems?
No problems except global warming and extinction of a few more species.

Quote:
Originally Posted by daan_odi_ View Post
Do you mean in terms of electricity?
Yes.
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