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Splitting one ethernet outlet to serve two computers

Posted on 2003-11-17
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Last Modified: 2007-12-19
I am currently rearranging my employees so that some offices will have two computers in them.  All the offices have only one ehternet outlet.  Is there a way that I can hook two computers up to the Internet through just one ethernet outlet?  Thanks.
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Question by:coldstreaminc
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by:Arrow_1
ID: 9767327
You just need to go to a local electronics store (Circuit City or Best Buy) and pick up an Ethernet Hub or switch. I believe you can also get Hubs for about $10 a piece on www.ebay.com or other internet sites like www.newegg.com or www.tigerdirect.com
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InteraX earned 50 total points
ID: 9767429
You can also get an ethernet splitter.
This enables you to have 2 sets of ethernet signals going down 1 RJ45 connector. As Ethernet only uses wires 1,2,3,6 for sending and recieving data on the cables.
Bear in mind that this does fall outside the ethernet specifications.
I'll try to find a supplier.
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by:coldstreaminc
ID: 9767459
Will using a hub or router work when I already have routers and hubs installed back in the switch room?  The network is setup so that the T1 line comes into the switch room and then into the router which is connected to to a hub which is connected to another hub.  The ports on each of these hubs connects to patch panels that are then wired thoughout the building to the ethernet wall outlets in each room of the office.  Will using another hub at the ethernet outlet mess things up as far as IPs are concerned?  
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by:InteraX
ID: 9767522
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by:InteraX
ID: 9767550
You can daisy-chain hubs/switches as long as you use crossover cables between the hubs/switches. IP's shouldn't be effected as these are logical addresses, not physical addresses.
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by:Arrow_1
ID: 9767674
You can connect as many hubs to switches and switches to hubs as you like.  There will be no adverse affects. The hubs are on the physical level wich means that they are equal to a length of cable as far as the computers and routers are concerned.  Your IP setup will be unaffected.
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by:chicagoan
ID: 9767790
>You can connect as many hubs to switches and switches to hubs as you like.
IF the switch is configured properly... a portfast setting on a switchport will start a spanning tree storm if you plug a hub into it., and you should plug only one hub into each switch port, while 100BaseT hubs are divided into two types, Class I and Class II, (one CLass I hub should exist in a single collision domain,two Class II repeaters can exist within a single collision domain) it's not a great idea.

The ethernet line splitter is an economical alternative and generally works OK, there's some crosstalk but not enough for the average user to complain about. It uses two switch ports on one end and provides two RJ45's on the other.


The 3COM intellijack is about the cleanest thing I've seen:
http://www.3com.com/prod/en_EU_EMEA/detail.jsp?tab=features&sku=WEBBNCNJ205SYS

There are some other manufacturers who make wall-jack switches as well.
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by:ShineOn
ID: 9768087
Just to clarify a tad...

Hubs are "repeaters" which constitute "hops" in the Ethernet 5-4-3 rule.  Switches essentially reset the "hop" count.  You are limited by that rule as to how many hubs are connected to hubs between devices.
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by:Arrow_1
ID: 9769142
For your situation, just connect a switch or splitter, don't worry about hop counts or any of that type of thing.  Just plug them in and they will do what you want them to.
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by:ShineOn
ID: 9769423
The best option is to buy a cheap, unmananged 4-port switch for each office that you want to have multiple devices in.

Netgear 4-port switches are a good, cheap example, and they won't add hops to your 543 rule.

If you want to go cheaper at the office end and put in 4-5 port hubs, I recommend you splurge on a switch on the back-end, which these days is also quite reasonably priced.


When you put printers in these offices, make them network-served printers and not locally-attached but network-shared printers.
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by:durindil
ID: 9770546
* Information only, and not intended to fuel the debate :)

By the way, an "ethernet splitter" or "Y adapter" is actually a hub according to ethernet standards (CSMA/CD.)  A hub is simply a hardware device where the individual wires inbound (8 of them in all) are split as many ways as there are ports.  Most accomplish this with a soldered junction (versus a switch where the junction is a logic circuit.)  This reduces the total transmission distance in direct proportion to the number of ports (100 meters/4 ports = 25 meters), and is why most hubs today are powered, to include a repeater.  So just remember if you are using a splitter or "Y adapter," remember to keep the length of your cable to a minimum.
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by:chicagoan
ID: 9771540
There are 'splitters' which are in fact 2 port hubs (radio shack sells one)
but we're talking about "line splitters", a passive device that uses the two unused pairs in CAT 3,5,5E cable such as:
http://www.connecttech.net/product_info.php/products_id/431


>Most accomplish this with a soldered junction...
IMHO - While a hub just takes the data that comes into a port and sends it out all the other ports, it is a little more complicated than a 'soldered junction'. Active circuitry receives each packet and sends it out to each port and is a 'multi-port repeater' in that sense.

>the individual wires inbound (8 of them in all) are split
While the Unshielded Twisted Pair wire used by therent consists of 4 pairs of wires (8 in total)  only two of the wire pairs are used in 10Base-T ethernet, one pair for transmitting data, and one for receiving data. In a hub or switch the others are not connected unless Power Over Ethernet is implemented, a technology that sends power across the cable for IP phones, wireless access points and the like. It is these wires that a 'line splitter' uses to create another 'home run' to the wiring closet.

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by:ShineOn
ID: 9771643
I strongly recommend against splitting a 4-pair UTP to carry two Ethernet connections.  Since my last name ends in "toboggan" (we can't spell that, so it comes out "ski") I can comfortably say that is a really Polish way to do it.  (Kind of like a person of African ancestry using the "N" word - OK for them, not for anyone else.)

If you want to maintain the Cat5 spec, you can't "split" the 4 pairs into 2 pairs.  Sure, 10-base-T only uses 2 pairs, but 100-base-T uses 4 pairs, and Gigabit ethernet also uses 4 pairs.  Putting a "splitter" on a 4-pair Ethernet connection isn't as simple as is putting a "splitter" on a cat3 phone connection to allow 2 lines to be carried over one wire.

Like I said before, either use a mini switch at the office endpoint or use a mini hub at the office endpoint with a switch in the wiring closet.
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by:chicagoan
ID: 9771899
WHile GIGe does use all 4 pairs and 100BASE-T4 did run on 4 pairs of Cat3 (or better), it's very unusual to see a T4 installation.

100BASE-TX is almost ubiquitous and runs on 2 pairs of Cat5.

100BASE-T2, runs on 2 pairs of Cat3 (or better) as well, but again you're not likely to run into it too much.
Technically, designs should not use the two spare pairs, but POE does and AT&T has gone so far as to couple video with 10/100 ethernet although some crosstalk is seen as it would be with a line splitter.
I agree, a switch would be ideal, a hub would be good, but you could use a line splitter.
One could argue that whether the crosstalk or the collisions on a hub would have a more deleterious effect on throughput, but we should leave that discussion for another day.

 

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by:InteraX
ID: 9771900
100 BASET also only uses 2 pairs. It isn't untill Gigabit that you start using all 4 pairs. This is due to the bandwith restrictions in place on the CAT5e cables. Not rated above 200MHz frquency or something like that.

Anyway, it is regardless outside the IEEE 802 regulations. This is a workaround which isn't perfect, but should work in a situation where you need 2 PC's to share 1 RJ45 connector at the wall and you don't have the budget to buy 20 or so small hubs/switches.
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by:ShineOn
ID: 9771987
But unmanaged 4- or 5- port hubs and switches are so dang cheap these days it makes little sense to use splitters.  You can get a 5-port switch for under $40 US, which gives you 4 end-node connections in a single-drop office, without compromising the cabling spec and without requiring additional ports at the wiring closet.
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by:chicagoan
ID: 9772133
Top five ideas not yet beat to death:

5:You could put another nic in the existing computer and use ICS with a crossover cable!

4:Nobody's mentioned wireless! DOH!

3:How about ethernet over the telco cabling!

2:Ethernet over the AC lines!

<drum roll>

1:Covert to arcnet, you could run 4 stations over 4 pairs and get the equipment for $1 a bushell!




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by:InteraX
ID: 9772210
Yeah, but we're having fun here....
;-)
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by:ShineOn
ID: 9772537
chicagoan - I would HOPE that we'd be talking about best-bang-for-the-buck without compromising future growth.  That means all of your top 5 don't fit the bill.

Sure, you could spend $15 on a cheapie NIC and do ICS, but that doesn't give you full access to the network, just to the internet access afforded to the first PC.

Wireless would cost more than a cheapie mini-hub or mini-switch.

I wouldn't even do ethernet-over-telco or ethernet-over-AC in my own home, much less recommend it to a business.

Arcnet is dead, and we should bury it rather than dig up its remains and try to reanimate it.

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by:chicagoan
ID: 9772639
"It's a joke, son"
Foghorn Leghorn
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by:ShineOn
ID: 9772655
I guess I missed the smirk and wink (smirk, wink...)
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by:chicagoan
ID: 9772777
Five exclamations points in any post should exclude it from serious consideration.



A crash reduces
your expensive computer
to a simple stone

anon
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by:drev001
ID: 9773287
Within the duration of this thread, I could have run an extra cable into each office !!!!! (count them)
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by:ShineOn
ID: 9773435
Then why didn't you?  

There are five exclamation points in your comment, so per chicagoan's standards it isn't to be taken seriously, so my response also should not be takent seriously!!!!!
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by:drev001
ID: 9774460
I would have done if I was the questioner :-)
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by:ShineOn
ID: 9774477
hehe...
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by:Arrow_1
ID: 9776583
The best way to do this would be to plug the northbound connection distributer into the internet coax inhibitor!!!!!
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by:Arrow_1
ID: 9776610
Now, back to the real help.  Your best bet would be to buy a hub or switch and just plug them in. You can get a good inexpensive switch at the following address. http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=308763&Sku=T156-1000&CatId=201
They are only $10 a piece. This will suit your situation perfectly.
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