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The in-wall CAT5e LAN cabling in my newly built house (photos during construction) is weird: it works perfectly fine except it only allows 100Mbps and not gigabit. To clarify, the wired LAN "connection information" in both Windows and Ubuntu says that the connection speed is 100Mbps. The status lights on the switch itself confirm this.

I've tried a few things now and found that I do get gigabit if I use a plain 10-meter LAN cable instead of the in-wall cabling! It would seem that the in-wall cabling is wrong!

How can this be? How can the LAN work fine insofar as I do get a normally functioning Internet connection, but not a gigabit connection?

You can see the actual punched wiring in the photos linked above, correctly following to the T568B standard to the best of my knowledge. I have punched all 8 wires of all 20 LAN cables, and I have successfully tested that each of these 160 wires is electrically connected to the corresponding wall socket.

I'm thinking perhaps the electrician messed up the wall sockets?

I'd love if I could fix this problem simply by re-punching a pair of wires for each LAN cable in the patch panel. Is it possible that some wires are just switched around? If so, which ones?

(Note: I've completely re-written my original question to reflect my new findings.)

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Try plugging a computer directly into switch with a pre-made cable. Do you get a 1GB link speed? Do you get 1GB if you connect a cable directly from computer to computer? Standard diagnostics would be to remove every variable, and test things one at a time until you find the problem. –  Zoredache Sep 12 '13 at 7:57
I thought the connection in a LAN is only as fast as the slowest connection.... Can you remove the switch and see if the speed changes? –  Dave Sep 12 '13 at 7:58
@DaveRook: You mean I should remove the router, right? That's the only non-gigabit device in my LAN. I'll try that. –  Torben Gundtofte-Bruun Sep 12 '13 at 9:01
@Zoredache: Good point; I'll try unplugging everything from the switch and only connect 1 computer directly to it. –  Torben Gundtofte-Bruun Sep 12 '13 at 9:03
Sorry @Torben, yes, you're right, I meant router. –  Dave Sep 12 '13 at 9:22

3 Answers 3

Okay, I'll take a shot and say it is the patch panel. As I seem to recall the spec, to be able to push Gig, you can't unwrap the cable more than about a 1/4 inch. Try and Google image search for gigabit punchdown panel and you can see the punchdown areas split with the cable going into the center and two pairs going left and two pairs going right so the untwisting can be limited. Yours appears to be the 10/100 type with almost an inch or so of untwisted length. Is the patch panel rated for Gig?

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You are right, I also remember this. But I don't think this has something to do with the actual problem. If this would be the problem the connectivity status from the operating system would tell him that it's a gigabit LAN but after trying to send data you would see dropping bandwidth down to something like fast ethernet. –  noggerl Oct 15 '13 at 21:21
During autonegotiation, both sides publish what they are capable of and test the connection before establishing what the actual speed will be. Autonegotiation is required of Gigbit. One way to test this would theoretically be to punch on one port of the panel a short patch cable and plug into that. –  Blackbeagle Oct 15 '13 at 21:40
Yes, the panel is rated for gigabit speed, but I see your point that the connectors are all in an inch-long row and not like in this image. I was not aware of this requirement and I'm puzzled as for how a 1/4" goal would be possible with the straight-line connector. –  Torben Gundtofte-Bruun Oct 16 '13 at 10:39
up vote 3 down vote accepted

Blackbeagle's answer was quite close, but not accurate after all. I've dug into something that I thought was probably unrelated, namely that the wires had an odd sequence, and that turned out to be the culprit! See photos below.

The essence is that the wall sockets (I took them apart) seem to be wired poorly but in the proper sequence, and the patch panel is wired according to the same standard... but somewhere, the labels must be mixed up because if I switch the wires around in the patch panel, it suddenly works!

Embarrassing admittance: In documenting this answer, I take a close-up photo of the patch panel's internal connectors and their labels. To my embarrassment, I notice that it's not labelled
1,2,3,4,5,6,7,8 but rather
1,2,4,5,3,6,7,8! Can you spot the difference?

I've rewired one port accordingly and now it works with gigabit speed! (This is why I didn't want to accept Blackeagle's answer.)

The wall socket is poorly patched but the sequence is okay:
enter image description here

Experimentally swapped the wires on one port:
enter image description here

That worked! Now I need to do the same on all the ports. That's when I discover...:
enter image description here
What?! The sequence is not as I thought it was. It's my own fault and I've been overlooking it all this time. I am embarrassed :-)

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Oh my God... It seems I'm not the only one in the world who got bitten by this patchpanel. My brother in law had one and I stared at it for about 2 hours without noticing the unusual ordering of the punch-block. Couple of day later I brought my laptop which an Intel NIC. The Intel Pro driver (NOT the standard Microsoft supplied one) has a wire-test option. That told me the wiring was wrong for Gigabit. After that I double checked the wall-sockets and the patch-panel and figured it out. –  Tonny Nov 27 '13 at 21:41
Thank you for backing me up and telling me that I'm not alone with this mistake :-) Let's make a self-help group for incorrectly wired patch panels! –  Torben Gundtofte-Bruun Nov 27 '13 at 21:47
If i ever going to install a patch-panel myself, i will certainly remember these two topics ;) BTW. No need to be embarrassed. I imagine many installers would stumble across something similar (early on) in their career (and never make the mistake afterwards). I take it the wall-mounts where installed before the patch-panel because otherwise the electrician who installed the wall-mounts should have discovered this when testing the connections on the wall-mount. –  Rik Nov 27 '13 at 22:33
Yes, the Wall mounts were installed during house construction (this summer) and I only set up the patch panel and switch after we moved in. The electrician didn't test it at all. –  Torben Gundtofte-Bruun Nov 27 '13 at 22:35
BTW as i see it know you needed to switch 3 wires in the patch-panel. 3,4,5 to 4,5,3 (while your cable tester only showed 3&6 switched. Does your cable-tester now give all 8 wires correct or did you need to rewire the wall-mounts too? Even if you have some pairs still switched it could work (transmit and receive pairs switched) but it wouldn't be 1-8 straight through. –  Rik Nov 27 '13 at 22:45

I'm not overly comfortable with whatever you have the wires terminated into. It does not look like any normal network termination panel I've ever seen. "Phone stuff" does not work with high speed networks...The very long section of straight, bare trace is as much or more of an indication that these are not Gigabit as the wire interface. But you state in the comment below that it's a Cat 6 device, so despite the way it looks, it should be more than capable.

You may also have non-Gigabit jacks - when "the phone guy" (uninvited) messed about with one of my (working) network wires and made them "pretty in a box with a jack", he used a non-Gigabit RJ45 jack, so they didn't work correctly after he screwed with them, until I ripped out his "helpful handiwork." I use Gigabit jacks when I bother with "make pretty in a box" and those work fine, normally.

If you own a crimper, pull off one of the wires from the patch panel and put a plug on it, then plug in directly. If you don't, go pick up a few Gigabit-rated jacks at [a home improvement or electronics store, or order them online] and you can punch your wires into them, and get yourself a new panel to hold them later. Pay attention to the color-code on them - the wires are NOT laid out in exactly numeric order. If changing the patch panel end does not solve the problem, change the jack at the other end as well.

The commentator @noggerl pushing cat 6 & 7 knows not of what he or she speaks, or has listened uncritically to too many cable salesmen going for the more expensive sale. Cat5e is fully capable for Gigabit to 100 meters, and Cat 6 & 7 can't go any further. While they may indeed have "lower noise and crosstalk", several billion Gigabit transceivers work just fine with the noise and crosstalk of Cat5e, and when they don't work, it's usually due to a problem that Cat6 and 7 are at least as, if not more, sensitive to; such as rodent-chewing, being pulled too hard during installation, or being bent too tightly. Cat5e cable is definitely NOT the problem with the installation failing to run at Gigabit. Every non-fiber part of my cable plant is Cat5e, except the old bits that are still Cat5 (from before the existence of Cat5e) and have not been replaced yet. Gigabit is perfectly happy on it (indeed, many old Cat5 segments will run Gigabit, but that's not a given).

10GB on copper is where Cat 6 & 7 come into play, and that's why cable salesmen succeed at pushing it in new commercial installs, and the more hopeful household installs that will probably never benefit in any way from it. If you really want to make your house futureproof, install conduits so you can pull the next thing into place without ripping the walls apart. Cat 7 will be quaintly amusing when every house has multiple 12-fiber ribbons running though it...

@DaveRook - each link is whatever speed it negotiates to or is capable of (or is set at manually, but if set manually above what it can do, it won't work.) Having a 100Mbit router plugged into a gigabit switch will not reduce the switch connections to other things (that can do Gigabit) to 100Mbit - it just means the connection to the router, or through the router, is limited to 100Mbit. I have Gigabit switches happily passing Gigabit traffic while having things as slow as 10Mb-half-duplex plugged into them. Naturally those things are limited to their own maximum speed, but it does not affect the speed of anything else plugged into the switch. Note that Torben got a gigabit link with a patch cord, probably while not removing all the other devices from the switch...

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Your suggestion that the wall sockets aren't gigabit-capable sounds like a possible cause! There is no reason to distrust the rest of the hardware though; the patch panel is a Dätwyler Unipatch Cat6 24-port panel and the switch is a HP ProCurve gigabit 24-port device. –  Torben Gundtofte-Bruun Oct 16 '13 at 10:34
Wait, now I understand your concern about the "straight, bare trace" - you mean the line on the circuit board between the cable connector and the LAN socket. Hmm, if you say that can't possibly be gigabit-rated then I could replace that panel which is certainly an easy option. Much better than replacing all the wall sockets for sure! –  Torben Gundtofte-Bruun Oct 16 '13 at 10:46
If it's a Cat 6 panel it should be fine, despite my not being comfortable with the way it looks. Myself, I've mostly gone to labelling the cables and putting plugs on them directly - the function of a "patch panel" is less relevant in small networks than it was with telephone lines - they all go into the switch, and rarely, if ever, move after that. –  Ecnerwal Oct 16 '13 at 11:59
I see what you mean, I could skip the patch panel entirely and remove an error source. I could crimp one of them and plug it into the switch to see if that helps. But there's not a lot of spare cable length so I'll soon run out of cable... Damn, should've kept the ends longer! –  Torben Gundtofte-Bruun Oct 16 '13 at 12:16
@Ecnerwal I don't know where you learned this but in my apprenticeship as electrician at one of the biggest german electricity suppliers the standard installation for network is minimum with Cat6, nowadays Cat7 is the more used way. The main reason for this is that the most network installations are combined with electric installations and the magnetic fields of the unshielded electric cables can interfere with the network installation. –  noggerl Oct 17 '13 at 9:07

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