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» Film-Tech Forum   » Operations   » Ground Level   » Can I Put Two LAN Circuits On One CAT 5 Cable? (Page 1)

 
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Author Topic: Can I Put Two LAN Circuits On One CAT 5 Cable?
Jim Cassedy
Phenomenal Film Handler

Posts: 1633
From: San Francisco, CA
Registered: Dec 2006


 - posted 12-05-2014 10:05 AM      Profile for Jim Cassedy   Email Jim Cassedy   Send New Private Message       Edit/Delete Post 
A 'cash only' theater is wanting to install a couple of credit card terminals
down at the box office & concession stand.

Because of the ancient building construction, pulling another line down from
the router location will would require drilling through several feet of concrete
and a thick plaster & lath wall, which is more work than I'm willing to do,
and that I don't have time for anyway with my busy schedule.

I only have room for one more cable in an existing conduit which contains
some low-voltage wiring that remotely controls the auditorium light dimmers.

So, my question is> Can I get away with pulling one cable and then "split"
the conductors at both ends to give me two, 4-wire LAN circuits for the
credit card terminals?


I haven't measured it yet, but I'd estimate the total cable run to be more
than 50, but less than 75 feet.

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Edgar Prass
Film Handler

Posts: 32
From: Tartu, Tartu county, Estonia
Registered: Mar 2013


 - posted 12-05-2014 10:33 AM      Profile for Edgar Prass   Email Edgar Prass   Send New Private Message       Edit/Delete Post 
Just use a simple hub or switch, no need to run parallel cabels for such low bandwitdh connections.

But what you want is also possible http://www.instructables.com/id/How-to-make-your-own-Ethernet-%22splitter%22/

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Randy Stankey
Film God

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From: Erie, Pennsylvania
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 - posted 12-05-2014 10:42 AM      Profile for Randy Stankey   Email Randy Stankey   Send New Private Message       Edit/Delete Post 
Would it be possible to use the existing cable to pull some Siamese Cat-5 through the existing conduit?

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Marcel Birgelen
Film God

Posts: 3119
From: Maastricht, Limburg, Netherlands
Registered: Feb 2012


 - posted 12-05-2014 12:07 PM      Profile for Marcel Birgelen   Email Marcel Birgelen   Send New Private Message       Edit/Delete Post 
If you do not need 100 MBit, you could, theoretically run 2 x 10 Mbit over those wires, but that's utterly nasty and I would advice against it.

Alternatively, you could get some cheap VDSL terminals, which can run on either two or four wires.

But a much cleaner alternative would be running VLANs trunked over the connection. The problem here is though, you would need a switch that can do VLANs on BOTH sides of the connection. Many affordable manageable switches can do VLANs nowadays though, but they're sometimes a little tricky to configure.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12639
From: Annapolis, MD
Registered: Dec 1999


 - posted 12-05-2014 12:34 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Oh stop...don't over think the solution here. Just get a simple 4-port or so switch. Use it as a "splitter" Plug the cable you ran into it and then plug each of your terminals into it. It is going to cost you very little for such a switch and premade cables.

The only possible reason to run a second cable in this application is if you wanted redundancy but that is about it.

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Carsten Kurz
Film God

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From: Cologne, NRW, Germany
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 - posted 12-05-2014 12:40 PM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
10/100 in the form of 100Base-TX uses only two of the existing 4 pairs. You can buy simple passive adapters that split from 1 CAT5 connector into two 10/100 capable sockets.
If you connect a now typical 10/100/1000 network card to it, it will negotiate to 10/100 automatically.

Small and cheap local switches are another possibility, as others pointed out.

- Carsten

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Marcel Birgelen
Film God

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From: Maastricht, Limburg, Netherlands
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 - posted 12-05-2014 01:28 PM      Profile for Marcel Birgelen   Email Marcel Birgelen   Send New Private Message       Edit/Delete Post 
What isn't clear to me if this concerns to different networks or just one. If so, a simple 4 or 8 ports switch for a few bucks will do just fine.

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Randy Stankey
Film God

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From: Erie, Pennsylvania
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 - posted 12-05-2014 02:11 PM      Profile for Randy Stankey   Email Randy Stankey   Send New Private Message       Edit/Delete Post 
I just assumed that he wanted two separate networks.

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Scott Norwood
Film God

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From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99


 - posted 12-05-2014 04:30 PM      Profile for Scott Norwood   Author's Homepage   Email Scott Norwood   Send New Private Message       Edit/Delete Post 
It would still be possible to run two separate networks over a single run of copper if there are switches on either side that support VLAN trunking (802.1Q). At that point, though, the word "cheap" is no longer part of the discussion....

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Marcel Birgelen
Film God

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From: Maastricht, Limburg, Netherlands
Registered: Feb 2012


 - posted 12-05-2014 04:47 PM      Profile for Marcel Birgelen   Email Marcel Birgelen   Send New Private Message       Edit/Delete Post 
quote: Scott Norwood
It would still be possible to run two separate networks over a single run of copper if there are switches on either side that support VLAN trunking (802.1Q). At that point, though, the word "cheap" is no longer part of the discussion....
VLANs are no longer a high-end feature, they can be found in plenty of reasonably priced gear nowadays.

I've used HP 1700-8 (J9079A) switches for this on small scales. Those do have 8 ports, are web manageable and do support VLANs. They also don't have fans, which is great for in-office solutions, where you don't want noisy switches lying or hanging around.

There might even be cheaper options from Linksys, Netgear, Belkin, Sitecom, you name it. As long as they support 802.1Q VLANs you're fine.

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David Buckley
Jedi Master Film Handler

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From: Oxford, N. Canterbury, New Zealand
Registered: Aug 2004


 - posted 12-07-2014 03:11 PM      Profile for David Buckley   Author's Homepage   Email David Buckley   Send New Private Message       Edit/Delete Post 
quote: Jim Cassedy
So, my question is> Can I get away with pulling one cable and then "split" the conductors at both ends to give me two, 4-wire LAN circuits for the credit card terminals?
Absolutely!

Go to your local Radio Shack (while you can!) and buy this

As noted above, "standard" 100mbit/sec ethernet uses two of the four pairs of a Cat5 cable, so one cable can handle two 100 mbit/sec connections with full compliance of the appropriate standards.

The two LAN "circuits" created by the splitters are entirely independent and isolated from each other, and thus they can be connected to the same LAN, or different LANs.

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Sean Weitzel
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From: Vacaville, CA (1790 miles west of Rockwall)
Registered: Dec 1999


 - posted 12-09-2014 01:48 PM      Profile for Sean Weitzel   Email Sean Weitzel   Send New Private Message       Edit/Delete Post 
Given that the devices are credit card machines I figure they both are on the same physical network. I agree with others just get a 4 port network switch to turn the existing "drop" into 3 drops.

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Carsten Kurz
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From: Cologne, NRW, Germany
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 - posted 12-09-2014 04:01 PM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
quote: David Buckley
Go to your local Radio Shack (while you can!) and buy this
Woah, you can buy a decent 5port Gigabit Switch for that money.

I can buy these passive port sharing adaptors locally for around 3€/piece.

- Carsten

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Marcel Birgelen
Film God

Posts: 3119
From: Maastricht, Limburg, Netherlands
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 - posted 12-15-2014 07:25 AM      Profile for Marcel Birgelen   Email Marcel Birgelen   Send New Private Message       Edit/Delete Post 
Personally, I wouldn't want to use those "Ethernet splitter plugs", as they're prone to create a highly confusing mess if you forget those things have been used. A switch is something most people are capable of comprehending.

Also, running two 100Base/TX signals over one Cat5(e) wire is cheating the standard and increasing the chance for interference. While it will work in most cases, those standards are there for a reason. [Wink]

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David Buckley
Jedi Master Film Handler

Posts: 525
From: Oxford, N. Canterbury, New Zealand
Registered: Aug 2004


 - posted 12-17-2014 03:35 PM      Profile for David Buckley   Author's Homepage   Email David Buckley   Send New Private Message       Edit/Delete Post 
quote: Carsten Kurz
Woah, you can buy a decent 5port Gigabit Switch for that money.
No, you can't - you can buy a dirt cheap switch for that price, with an ever cheaper power supply.

quote: Carsten Kurz
I can buy these passive port sharing adaptors locally for around 3€/piece.
Thats lucky then. I can get them cheap, but not locally, and, of course, we all support our local retailers, don't we [Smile] And, time being money, I'd rather drive down the road and lose 20 bucks then lose an hour traveling to somewhere cheaper. Your mileage may, of course, vary.

quote: Marcel Birgelen
Personally, I wouldn't want to use those "Ethernet splitter plugs", as they're prone to create a highly confusing mess if you forget those things have been used. A switch is something most people are capable of comprehending.
OK, I'm an (ex) networking professional, and I can understand port splitters. I didn't realise that you have to be not "most people" to understand them. Perhaps I guessed wrong?

They certainly don't creeate a "confusing mess": under the desk in the kiosk there is less wiring and stuff with a port splitter than there is with a switch. And... less to go wrong.

quote: Marcel Birgelen
Also, running two 100Base/TX signals over one Cat5(e) wire is cheating the standard and increasing the chance for interference. While it will work in most cases, those standards are there for a reason.
If you are aware of a standard that port splitters "cheat", I'd like to hear about it. It certainly doesn't increase the chances of interference, and its a good job really, as there are networking cables with far more than the four pairs of copper that cat 5/6 uses.

Sure, one can put a toy switch under the counter, but it's a single point of failure that when it fails it'll take out both card machines. Or it could just have its wall wort knocked out when a box of ticket blanks is placed under the counter.

Fault-finding is more tedious, as with a toy switch there are two places to look at the blinking lights to figure out what has broken, rather than the one place if a splitter is used. (assuming a non-managed central switch; if the big switch is managed then the argument is even more pervasive)

Bottom line is this: if there were two network ports available then Jim would have used them without a second thought. As this is not possible, the question then becomes one of what is the least bad alternative? Given the circumstances of the installation, any networking professional would advise a port splitter solution. Using a toy switch brings no functional advantages (ie it doesn't work any better than the port splitter) and is more to go wrong. Its a no brainer.

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