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[Ronski]

When I got to work this morning my PC showed no internet connection - I could only access equipment in my office.

The main office still had internet and no networking problems, so I set about trying to diagnose the problem at the same time as doing my normal work, which is not easy.

My office is down the other end of the building, and I estimate about 80 meters worth of cabling is between the switch in my office and the switch in the main office, a large extent of this runs externally with some internally. The cable is divided into two sections where it's joined by a cable connecting two sockets in the old server room, which did prove useful as a test point. This established the problem was in the second section, on checking this length of cable no visual faults where found.

Back underneath my desk checking the socket there caused the PC to try and connect every time I wiggled the cable in the wall socket, a different cable made no difference, so I presumed a faulty socket and proceeded to change it using a krone tool.

On connecting the wall socket to the switch it still appeared dead, so I plugged the cable directly into the laptop and it connected at 100Mb (it has a gigabit port), connecting directly to the PC it connected at 100Mb, again it should be Gigabit.

I checked the wiring and one of the brown wires wasn't fully home, or I may have even got the two the wrong way round, can't remember now, anyway after correcting that the PC would say connecting, then not connected, then connecting, eventually even this stopped. The laptop wouldn't connect either, different cables made no difference either.

So I pulled all the wires out, cut the cable back about 75mm and reconnected again, still nothing. I even put the switch between between the two connections where the link was in the old server room just in case the length of cable was a problem, but alas it made no difference.

Now the socket module I removed was a 258A, and the new one is a 568B, as far as I could tell by googling from my phone these both use the same pin to terminal colour codes, does anybody know any different?

Old socket module:


New socket module:


Only option I've got tomorrow is to order up some CAT6 external cable and run it in on Friday, unless of course the computer engineer we use when the need arises actually rings me back and is available to fix it.

[burakkucat]

Have you checked the Pin No. v Wire Insulation Colour at the other module that is at the other end of the length of cable?

I know that there are two separate wiring schemes, the "A" and the "B". The more "helpful" modules will actually show the relevant colours for each scheme type per pin.

[Ronski]

I had intended to, but didn't - I will check that tomorrow morning, thanks.

[sevenlayermuddle]

When cabling up my home some years ago, I found an incredibly useful feature of my old Dell PC.  It was a cable tester built into the NIC, and accessible by drilling down into the device manager menus.   For hard faults it would give distance to fault, which proved pretty accurate.  It also gave a 'quality' assessment that, I think, was meant to identify issues like wires bent around too tight a radius.

Maybe worth a look?   But that was a 2008 machine running XP. I have no idea whether newer NICs, and later Windows, have improved/maintained/discarded that functionality.   

[c6em]

You need to check very carefully
The modern two standards are T568A and T568B
The differences are that a couple of wire pairs (orange and green I think) are swapped round
Version B is more commonly found however Version A is required in some places( (US Gov being one) and is said to have a more rational progression of colours though the wiring sequence of pins 1 to 8.
You can wire up in either standard provided both ends of the cable you are connecting up have their terminations (plug, socket etc) are wired up to the same version.

Now I THINK that the modern T568B is equivalent to the very ancient old 258A standard..........

[Ronski]

@7LM now you mention it I do remember seeing something similar in one of my PC BIOS's recently, no idea which one but I'll take a look at the works one tomorrow, thanks.
@c6em I was aware of the 568A & 568B, I've always used B when installing my own networks simply because I remember to use that one by thinking of B as standing for Best (not that it is). However finding the socket marked 258A did throw me a bit. What you THINK would also concur with what little information I found earlier that stated they are the same, thanks. The socket was installed just after 2000 (maybe even a few years after), so no idea why it's so ancient, unless just old stock being used up.

Anyway I going to do as BC suggested, also take a look in the BIOS and I'm picking up a network cable tester on the way to work in the morning.

[Ronski]

Normal service is resumed.

Checking the socket in the old server room it was wired up as 568A, using my newly purchased  network tester showed this and one wire disconnected. Swapped the wires in the old server room module, and then it showed just a disconnect on terminal 3, so pulled that wire my end and remade it and all good, back up and running at 1Gbps 

In this case it would seem that the 258A socket matches a 568A socket

Frustrating time yesterday, but so simple to fix with the correct tools and checking the other module.

Thanks to all that replied.