Completely weird cable problem in new house - need insights pls!

The key is speed. If you can get it to work at 10BaseT, you have answered your own question. CHECK THE WIRING!

Pull the jack out and you'll probably find a transposition of wires.

Carl Navarro

I don't understand. 10BaseT and 100BaseT use the same pairs of wires on the cable. How could the speed at which I connect illustrate trasposed wires. In any case - transposed wires would mean that the cable is a "crossover" cable, right? Or do you mean that it is transposed with a different "unused" pair.

Here's a chart of what as able to connect where:

Switch uplink: 100BaseT, link, FD -> no ping, dhcp Switch regular: 100BaseT, link, FD -> no ping, dhcp Xbox: no link light Win2K laptop: no link at 100BaseT, link+ip+dhcp @ 10BaseT WinXP laptop: link + ip + dhcp @ 100BaseT Linux box: Link light on ethernet adapter (not sure what speed), no dhcp or ip

What my theory/hope is - certain network adapters have better error correction and can copensate for some signal loss. I have a bunch of old Ethernet adapters around. My hope is plug a bunch of them in the linux box, and hopefully one will link up and get an ip.

If you go slow enough you can use the top barbed wire of a fence with earth as the return path. As speed goes up, wiring issues become more critical.

Checking the wiring config in the jacks is a good place to start.

What Carl might be saying is that the pins 1 & 2 (typically the wht/org & org/wht pair and pins 3 & 6 (wht/gn & grn/wht are transposed at both ends. Not likly, but thats the one way you would get a working connection and also be a slow one, i.e.

1 > 1 2 > 3 3 > 2 6 > 6 Here your date is going in one direction on the wht/org & wht/grn and org/wht & grn/wht in the other direction. But again, that would mean you have a wiring error in two places. Not likely, but can happen.

I've seen instances where both ethernet indicators light up at both ends, but still be miswired and of course no data goes through.

Have also seen instances where you have to force the NIC to 100 Mbps instead of auto-detect.

Cross-over and straight-through cables might and not work all the time. If at least one device has the ability to detect and adapt to the correct wiring scheme, then you might be able to use either cable. Even if both devices can auto-detect, it may or may not work. It all depends on the particular devices and NICs you're using.

snipped-for-privacy@gmail.com wrote in part:

Easily: A miswired cable (split pair) can often carry

10 MHz 10baseT but will fail at 100 MHz 100baseTX. Ditto for other cabling defects like untwist.

How are your plugs wired? T-568A or T-568B?

-- Robert

The premise you have to work with is that 10BaseT works on Category 3 cable (with no twists), and can work on any 4 wires, probably even QUAD cable for a short distance. (or as someone else said, barbed wire :-)

Electrons are blind. They need pin 1 to go to pin 1 2 to 2 3 to 3 and

6 to 6.. (called straight through wiring). The pins that apply in an Ethernet connection are 1,2 3 and 6. So you could wire the blue white to 1, the orange white to 2 the green white to 3 and the brown-white to 6 and pass data at 10 base T speed for maybe 20 or 50 or 125 feet.

When you turn up the speed, you need pairs 1&2 to be twisted and 3&6 to be twisted, tightly, as in cat5e.

The cheap tester will tell you that the wiring is electrically correct, but it won't tell you that the pairs are correct. A better tester will tell you that you have a split pair, and the best tester will tell you that you can't pass data.

You can start by just LOOKING at the color codes.

The 568-A/B the everyone talks about is

White/Blue goes to 5 Blue White to 4 White Orange to 1 Orange White to 2 White Green to 3 Green-White to 6 White-Brown to 7 Brown-White to 8 Thant's for 568-B. Reverse the Orange and Green Pairs for 568-A. THERE IS NO OTHER COLOR CODE FOR ETHERNET.....

Both ends need the same color code and letter (your electrician/wire person did follow the designations on the jacks, right?)

I'm guessing you'll find that the person wiring made up his own code. There isn't much else to say. It's not going to be one end is A and the other end is B or you would not pass ANY data.

Carl

(snip)

I have seen similar systems where only one end was miswired, such as exchanging pins 3 and 4. You might think it wouldn't work at all, but there was enough signal to get the link light on, and almost make the connection. (static IP addresses.) It worked well enough that it took a while before I decided to check the wiring.

-- glen

And one of the Tempo testers can light up the lights on your hub and PC's network card. So you can't go by just the lights lighting up.

Thank you so much to everyone that replied to this thread. I found the problem based on your suggestions. I looked at the crimped RJ45 jack in the box in the garage, and I saw that the orange wire was in the 7 pin position, next to the brown wire. I'm not even sure how this cable could even send a signal.

I've called the builder's electrician and they are going to come out and check it out. Thanks a lot!

Heh - it figures the one cable that I need most is the only one that's mis-wired.

--Min

snipped-for-privacy@gmail.com skrev:

So they "forgot" to test the installation ? The least they should have done was to ensure that their work was OK. You should ask them to test all outlets as they clearly didnt do that after the installation was done.

Oh.. It was wired by an electrician.. that explains a lot..

Most electricians barely understand the concept of home-run cabling, and very few understand data wiring. I wouldn't be surprised to find the cat5 stapled in the walls, or pulled extremely tightly around corners..

That is slowly changing, but you're generally going to have better luck with the folks who do network and telephone cabling as their primary business.

Err. Cat 3 is twisted, just not as much as cat5.. even the old paired station wire is twisted, if you can call 1 twist per foor "twisted"..

I remember once driving out in the desert and watching the power poles on the side of the road. In most cases it is three wires going along to the same position on the next pole, but once in a while, maybe every mile or so, there is a different pole with four insulators, such that one goes over the top and continues out on the other side. The result is one twist every few miles, maybe about right for a 5000km wavelength.

Also, even Cat 1 cable is twisted.

-- glen

Yeah, I've spent a huge amount of time cleaning up after such electricians recently.

(See "Fiber Success - Netgear GS716T and GS724T models with LANBasics OT-2201 SFP modules " in comp.dcom.lans.ethernet (

) First they pulled pre-terminated outdoor-rated fiber through water, not by the protected end with a padded pulling eye, but by the other end, with a bit of tape, caking the fiber end with dirt. (Optical fiber and dust or oil don't get along, let alone clumps of dirt). Then they installed and terminated some Cat5 such that there was too little jacket, so it didn't crimp (like ). I pointed this out and asked 'em to redo them and let me know. They redid them and didn't tell me. I finally realized the the network extension I was completing days later wasn't working because their redo job had made things worse by breaking the existing network - now there was no link light because they hadn't crimped the cable, but rather had shoved it into a switch jack, uncrimped, and with uneven-length wires. I ended up redoing it all myself.

Oh, and on top of all that: They had asked if they should do T568-A or B, and I said either, but be consistent (since it seems to be a big-endian-small-endian type of dispute). They said they'd do T568-A, but instead, they made up their own scheme.

"crimped RJ45 jack"?? If the cable is crimped directly to an RJ45 plug then it's already sub-standard. The in-wall cable is solid, not braided like patch cables, and needs to be terminated in a patch panel. I can't even count the number of small offices I've seen that are too cheap or inexperienced to do it right, and end up paying someone like me to fix their network problems..........Oh wait, forget I said anything. I want all you cable guys that crimp plugs to building wiring to keep it up, you're sending my kids to college.