In-Wall Ethernet? Woo-hoo!

September 15, 2011 2:33 PM

Ethernet ports in every room, but none of them work. The brains of the system which is in the wall of a closet is a Square D Multi-Link Structured Wiring System. How do I find out how it's set up and how do make it work as it should?

I've just moved into a new apartment and there are multiple ethernet jacks in each room which all lead to the wiring box in a closer. None of the jacks seem to communicate to one another. I'm familiar with networking, however not so much with raw wiring in walls which may or may not be connected to electricity (a PoE situation makes me nervous).

Each section of the split ethernet cables seem to be labeled, but I don't really know what to do from here? Ideally, I'd like each to talk to one another and I have spare switches if I need to put one in there, although I'm sure the whole purpose of the box is to take care of that.


Pictures of the wiring unit:

Image 1
Image 2
Image 3


All help is appreciated.

posted by cgomez to computers & internet (20 answers total)

That unit just splits off two 4 pair cables into 8 separate pairs that go to different rooms...

How many jacks are there total?

Where do those 4 pair cables go to? Is there a router or something?
posted by empath at 2:42 PM on September 15, 2011

That's not ethernet wiring. Ethernet requires (at least) 2 pairs per jack. Maybe it was a phone system.
posted by and for no one at 2:45 PM on September 15, 2011 [1 favorite]

Yeah, there needs to be a switch or a router somewhere. Is there a box above this box?
posted by The Bellman at 2:45 PM on September 15, 2011

That's basically just a punch block, btw. There's no brains there, it's all physical connections between wires.
posted by empath at 2:45 PM on September 15, 2011

That one cable coming to the top left. If you can figure out where it's going and plug your router into that you might be good to go, but it looks like only the first two, transmit, pins for the other jacks are wired in, I'd expect to see 3 and 6 connected as well. Could be this was being used for phone and you might have to wire in 3 and 6 for each of those jacks yourself if you want to use it for Ethernet. How many wires from each of the Cat 5 cables are connected on the back side of the block?

Ethernet wiring diagrams.
posted by IanMorr at 2:47 PM on September 15, 2011

Oh and and for no one is right.. you can't run ethernet over single pairs..
posted by empath at 2:48 PM on September 15, 2011

That's not ethernet wiring. Ethernet requires (at least) 2 pairs per jack. Maybe it was a phone system.

Well it claims to be CAT-5 cable, but you're right, it's not punched down for Ethernet. Can you send us a picture of a jack?
posted by The Bellman at 2:48 PM on September 15, 2011

Also, if you're renting, don't mess with this stuff without talking to your landlord.
posted by empath at 2:49 PM on September 15, 2011

If the cable and jacks are good and they were just using a few pairs for phone, you could pull out that punch block, put ends on the cables, stick a switch in there, and you'd be good to go.
posted by The Bellman at 2:50 PM on September 15, 2011

you can also pull through 2 extra pairs to four of the jacks and have 4 ethernet ports...
posted by empath at 2:51 PM on September 15, 2011

(err.. one extra pair -- two pairs total for each jack)
posted by empath at 2:52 PM on September 15, 2011

Lots of new construction uses cat5 even for POTS jacks, fwiw.

The one pair that's punched to all of the jacks is presumably your normal phone service.

"Dining 2" has some extra pairs hooked up; does it have any networking ability?

My guess is that what you need to do is find out where the other end of the white wire coming in from the top is, and attach that to your dsl/cable/whatever box; and then in the wiring box, either connect the wire through to a single room whose networking jack you want to work, or put a small switch in there.
posted by hattifattener at 2:52 PM on September 15, 2011

(Also, the rules on running cable usually prohibit mixing low-voltage and high-voltage wiring. In theory it should be safe to muck about in there. Though admittedly, a normal telephone ringing signal is 80VAC which can give you a bit of a jolt.)
posted by hattifattener at 2:54 PM on September 15, 2011

POE isn't dangerous, either, it's DC power and low voltage.
posted by empath at 2:56 PM on September 15, 2011

Thanks for the responses. Seeing as there are so many jacks (which have all eight contacts), it would seem like a safe bet that it is for networking rather than phone although it might have been configured that way. I've attached more photos below to help. And I'd have a router attached at one jack. Would I need to put an actual switch inside the box to connect the rest?

Wall plate and ethernet ports
Box Close-up 1
Box Close-up 2
posted by cgomez at 3:13 PM on September 15, 2011

To be clear, those are simply pairs of wires. There is no network here unless there is some device like a router or switch hooked up that you haven't shown a picture of. That block is just for physically connecting wires together. It's not even a hub.

The rooms that have more than 1 pair (that is that have 4 or more wires) going to them can be used for ethernet. The rest would be only good for phone.
posted by empath at 3:18 PM on September 15, 2011

If it helps you visualize this, draw a diagram tracing out all the pairs and where they go to.

Each one of those pairs will start at the jack, go through that block, and then terminate somewhere else. To have an ethernet cable, you need to have 2 pairs, minimum.

You need to find the other end of those pairs, and terminate them with ethernet plugs and connect them to a router before you have a network.
posted by empath at 3:24 PM on September 15, 2011

You could unpunch the wall cables and put ends on them, but you will need to know how the wall jacks are wired so you can put the ends on to match. Ethernet at 100mbits or less requires 2 pairs (1+2, 3+6); gigabit ethernet requires all 4 pairs. One pair is split (3+6) around the middle pair (4+5) at the connectors and jacks. Colors on the jack punch blocks deal with this correctly using one of two configurations.

Here's a diagram for the likely ways the wall jacks are wired.

This isn't rocket science, but you might look for local help, if you know any nerds.
posted by and for no one at 3:53 PM on September 15, 2011

I guess I'm repeating what others have said: Right now, those "ethernet" cables are set up to carry phone signals. Check with your landlord before doing anything to change that. Assuming your landlord allows it, and assuming there are full ethernet cables (not just single wire pairs) going to each of the jacks you want to use for ethernet, the easiest way to get a network working is to terminate the cables with 8P8C plugs (sometimes called RJ-45) (easy to do with a crimper, but there are two common configurations (A & B) for ethernet cables, and you'll want to terminate the cables in the same way they terminate at the jacks, so you'll need to take a look at how the jacks are wired). Then plug them all into the back of your router (or into an ethernet switch that is connected to your router), and you'll have a wired ethernet network.

The box you have now is not a switch and cannot replace one. As others have pointed out, all it does is provide physical contacts among wires.
posted by dilettanti at 7:19 PM on September 15, 2011

Hmm IF your landlord allows it you can get a patch panel and punch down the ethernet wires to the patch panel effectively making those ethernet jacks in each wall network jacks.

PS rj11 for phones will work in a rj45 jack.

You can also get adapters that put a jack at an end of an ethernet cable without tools. that would also work.
posted by majortom1981 at 7:59 AM on September 16, 2011