How do I wire a network socket with 2 ports?

January 22, 2007 2:15 AM

If i want to install a network socket box in an office, each with 2 ports, how do I wire it?

I have been tasked with wiring up a few newly available offices at my company in order to get them on to the network. I know how to do this for both ends of a CAT5 cable and I am no stranger to wiring up a simple network with a router and a few hubs and switches.

For this project however, I want it to look nice and pretty with this kind of network jack (German) installed on the wall. Each box has 2 RJ-45 jacks on it. I have searched and searched but I can not determine if there is a special way to wire this sort of connection.

• Do I run 2 lengths of CAT5 to each box (thus doubling the expense of cable)?
• or do I affix the end of one cable to the back and the internal wiring takes care of the rest?
• Or, do I have to really use my brain and figure out how to carry 2 data channels over 1 length of CAT5, employing some sort of y-splitter cable?
• something else?

I mention the idea with the y-splitter because I know that with 4-twisted pairs, it is possible, in theory, to be done but I'm not sure if it is practical or common in this situation. Would anyone with experience care to drop some knowledge about how this is done?

I called the place selling this but they (sales) weren't really helpful.
Da fragen Sie mich viel zu viel!

posted by chillmost to computers & internet (20 comments total)

Use separate Cat5 cables for each socket.
posted by flabdablet at 2:41 AM on January 22, 2007

How coincidental - I'm currently spec-ing out a hospital with similar snagless, angled plates to prevent breaking when beds roll into them.

Such network plates are usually part of a modular system - the plates themselves are simply blanks into which a number of jacks can be inserted (in your case female RJ45). They usually also sell additional module types like voice, video, audio, fiber, blanks, etc. The most common 'term' for such a female RJ45 jack is a 'keystone jack'. They look like this. While I can't find such jacks on your site, here's an example from a fairly popular american manufacturer:

Angled wall-plate
Keystone Jack

These jacks have their own wiring order which is clearly marked on the business end of the unit. They can be wired by hand, but I dont recommend it. There is a special tool for wiring keystone punch-downs (visible in the jack link above). It's dangerous (high force require to punchdown) and costs butt-loads of money - making wiring only two of them not a very cost-effective solution. Good luck!
posted by datacenter refugee at 3:41 AM on January 22, 2007

Oh and about the Y-splitter idea, don't do it. You'll turn the single cable into a shared segment, ruining any benefit you'd get from a switched infrastructure and allowing each occupant to potentially listen to the other's traffic (big no-no if you have any customer info privacy regulations you need to be concerned about).
posted by datacenter refugee at 4:04 AM on January 22, 2007

I've wired a punch-down keystone jack with no tools, just a knife. It's not that difficult. I think you can, in fact, use one cat-5 cable for both jacks, using four wires for each. You don't need a special splitter cable since you're attaching the wires individually, but gigabit ethernet requires all eight wires, so if you want future-proofing, use two cables.

I don't think datacenter's second comment is correct: if you use four different wires for each connection, it won't have any noticeable effect on privacy etc.
posted by alexei at 4:07 AM on January 22, 2007

Yes, run two separate Cat5 cables. Be sure to check with local code in regards to using Plenum rated cable or PVC jacketed cable. Cable is really inexpensive, and to run it after buildout will be much more expensive.

In America, Leviton and Hubbel are very popular brands, but not so sure for Germany. Most (again American) jacks are the modular jacks, that require a 110 Punch Tool (first link from google). Do NOT use a knife or screwdriver, or whatever small thing you can find.

I'm too lazy to research, but it's possible that in Germany, the standard is to use a Bix tool, Krone tool, or 110 tool. You will most likely NOT find a modular jack insert that uses a 66 tool (I've never seen one, nor can I imagine how it might work).

On the other side of the cabling, you will want to connect it to a patch panel that uses 110 punchdowns (or German equivalent) on the back side. Both the modular jack inserts, and the patch panel should use the TIA 569B specification (but I've seen some where both use 568A - usually not Token Ring).

If you REALLY REALLY have to use one cable for two jacks (I've done this many times, but only when pulling new cable wasn't an option) be sure to use the correct pairings necessary for the twist ratios to not cause near end crosstalk. Orange & Green pairs on one jack ; Blue & Brown pairs on the other jack. But, seriously, don't do this. My previous post on this topic.

I can answer more if needed.
posted by stovenator at 4:37 AM on January 22, 2007

Last time I tried to do the double port thing, it was quite the fiasco. You lose alot of range by running two lines on the same cable. Just run two cables.
posted by effugas at 4:38 AM on January 22, 2007

(568A - usually is Token Ring)
posted by stovenator at 4:39 AM on January 22, 2007

Two cables. Cable is cheap, and you never know what you'll want to use the cables for later. Maybe you'll want to use VoIP phones that Power over Ethernet, using the second pair to put 48V down. Maybe you will upgrade to Gigabit Ethernet, which uses all four pairs.

The back of the socket will have sixteen terminals separated on two sides, one for each cable. They be labeled with the appropriate colours, like this. If you have a choice, use T568B wiring. In any case, make sure you use the same wiring on both sides.

Untwist as little wire as possible.

If you are lucky, the sockets will come with small plastic punch tools. If not, you can easily find them on the 'net.
posted by stereo at 5:40 AM on January 22, 2007

Thanks for the info.

stovenator: On the other side of the cabling, you will want to connect it to a patch panel that uses 110 punchdowns

I was just gonna run the cables to a switch up in the attic and connect with a usual RJ45. Are you implying that it shouldn't be done like that? Or did I misunderstand?
posted by chillmost at 5:42 AM on January 22, 2007

It should be punched down onto a patch panel, and then standard RJ-45 cables can be run from the patch panel to the switch. The main benefit to this is a cleaner install, and it gives you the ability to expand or change configurations easily.

If I understand what you're saying, you wanted to crimp mod plugs onto the end of the cable. You can do this, but it's not generally accepted as the right way to do it.
posted by stovenator at 6:08 AM on January 22, 2007

Accessible patch panels are good because they let the building user (who many, eventually, not be your present organization) reconfigure the signals that go over those Cat5's to suit their own needs. For example, somebody might decide that your paired outlets make more sense to them as one network, one phone point.

This is harder to achieve if there's no patch panel and all the far ends are terminated to a dedicated device somewhere inaccessible/unknown.
posted by flabdablet at 6:09 AM on January 22, 2007

I was just gonna run the cables to a switch up in the attic and connect with a usual RJ45. Are you implying that it shouldn't be done like that?

In most cases, the closet side of the cable is not terminated in a male rj-45, but a female one as part of a patch panel. Patch panels make life easier for you should you need to swap out various parts of the telco closet (electronics, short patch cables) without having to cut or move existing network drops. The way you mentioned is fine as well, just expect to be lectured by the next telecomm guy you hire when he sees it :).

if you use four different wires for each connection, it won't have any noticeable effect on privacy etc.

Correct - but you increase cross-talk, shorten the maximum drop length due to interference and rule out ever being able to use gigabit ethernet or PoE on the drops.
posted by datacenter refugee at 6:09 AM on January 22, 2007

s/many/may/
posted by flabdablet at 6:10 AM on January 22, 2007

By the way... Anybody want to hazard a guess as to whether or not Krone is the standard in Germany? 110 is standard here in the US. I've used Bix in Canada on a couple occasions. I've heard rumors that Krone is standard in Australia.
posted by stovenator at 6:26 AM on January 22, 2007

I'm in Australia and all I've seen is Krone.
posted by flabdablet at 6:36 AM on January 22, 2007

I did find this called a Krone Einlegewerkzeug . Is that what you are looking for?
posted by chillmost at 6:41 AM on January 22, 2007

Well, looking at these tools it isn't clear what is standard. But, yes that is what YOU are probably looking for.
posted by stovenator at 6:46 AM on January 22, 2007

Oh, and one more thing. Be sure to get solid core cable (not stranded), or you will get flaky connections on the punchdowns on your patch panels and jack inserts.
posted by stovenator at 7:00 AM on January 22, 2007

Power over Ethernet does not require a 4-pair cable:

Two modes, A and B, are available. In mode A, pins 1-2 (pair #2 in TIA-568B wiring) form one side of the 48 volt DC supply, and pins 3-6 (pair #3 in TIA-568B) provide the 48 V return. These are the same two pairs used for data transmission in 10Base-T and 100BASE-TX, allowing the provision of both power and data over only two pairs in such networks.

In mode B, pins 4-5 (pair #1 in both TIA-568A and TIA-568B) form one side of the DC supply and pins 7-8 (pair 4 in TIA-568A and TIA-568B) provide the return; these are the "spare" pairs in 10BASE-T and 100BASE-TX. Mode B, therefore, requires a 4-pair cable.

The Power sourcing equipment (PSE) decides whether power mode A or B is to be used, not the powered device (PD).

The same thing goes for Gigabit Ethernet, actually, although that is more of a technicality. The gear that does gigabit over two pairs of cat-6 isn't common.

The real question is, are you trying to do this on the supper cheap, or do you just want to be sensible about it? If there is good reason for saving the money, forgetting the patch panel, and using all pairs in the cat-5/6 are options.. They just aren't good options, if you can afford to avoid them.
posted by Chuckles at 8:38 AM on January 22, 2007

Thank you everybody for your help.
posted by chillmost at 1:02 PM on January 22, 2007