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I just got hired into a new company where no IT has been before. My first task was to identify the possible problems. This is what I first saw, when checking on the cables connected to the switch, I noticed a different color coding in this order:

White-green Green White-orange Orange White-blue Blue White-brown Brown

This is the cable connecting to the switch. Haven't checked the color coding yet on the network outlet.

Is the color coding very wrong and should have them replaced for everything?


Thank you everyone for the prompt reply.

I have checked the color coding from the RJ-45 directly connected to the switch. I have yet to check the punch down configuration.

There is no patch panel yet. The connection is basically like this: Workstation > Outlet > Switch.

By the way, cables used are Cat5-e. The company is a 3d animation company and large files are required to be transferred on the file server. We do encounter slow file transfer a lot.

The way I'm seeing it, the color coding used was not a T568a or T568b standard. It is rather color coding scheme somehow of its own. Does this also explain the slow file transfer?

Another thing I would like to consult with is the network speed. The computers and switch (D-link DGS 1024-D) are both capable of Gigabit connection. Yet only the two file servers are getting Gigabit connections and the rest of the workstations are 100Mbps (others are even 10Mbps).

  • A picture speaks a thousand words. Can you take a close up photo of what you're seeing? That is certainly an odd wiring choice if this is a patch cable, but who hand-makes patch cables these days? Hand-making it would be the only way I can think of that would do this. – Mark Henderson Apr 13 '15 at 2:52
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Where was this cabling that you checked? Was it inside a patch cable, or on the back of a patch panel with a punch-down? (this is not obviously clear from your question).

If it was on a punch-down, the internal connections of the external blocks to the internal pins is not obvious. Different punch-downs have different wiring requirements, so you'll need to check the actual wiring against the standards that the punch-down has. (These are usually printed on the terminal block itself). There is two standards, T568A and T568B. You need to be consistent with which version you use.

Typically I see older installs with T568A and newer installs with T568B, but there is no hard and fast rule about this. One place I saw T568A on half the connections and T568B on the second half (newer installs).

enter image description here

In that photo you can see the different pinout diagrams on the inside of the terminal block. Some block have it on the side of the block, and others have it on a plastic cover that goes over it.


Based on your update, this is certainly wired incorrectly. I would check the wiring at the wall socket end, and get a contractor in to wire them correctly (try by just cutting the ends off and re-crimping them correctly. You should not need to re-run the cabling unless the cables are physically faulty). Yes, cross-talk can greatly affect transfer speeds. If your workstations are only negotiating 100Mbps, or are negotiating gigabit but only getting 100Mbps equivalent speed, then I would definitely be getting this looked at.

Ultimately even if this doesn't actually solve your problem, at least you've fixed it for the future, as you're likely to get into headaches if you ever did upgrades to the wiring.

  • Anyway terminal equipment uses pairs 1-2 for ethernet therefore its cable SHOULD be 11233244, not 11223344. – Kondybas Apr 13 '15 at 3:09
  • @Kondybas yes, but the external blocks do not map 1:1 to the internal pins. I have seen terminal blocks where the order that you punched them down in did not have an obvious mapping to order of the pins. In fact I saw one where you punched all the solid colours on one side, and all the white/solid colours on the other side, which is wrong until you account for the internal connections of the terminal block to the pins. – Mark Henderson Apr 13 '15 at 3:11
  • I know, but anyway any cable attached to the terminal equipment should have properly twisted pairs. Despite of inner patch-panel wiring, because all terminal equipment have standard PHY. – Kondybas Apr 13 '15 at 3:36
  • Also, pairing of wires SHOULD be preserved on the all the route from terminal equipment to the first active node of network. When the cable is splitted by p/panels, the pair going out from the PC should be the pair all way long to the switch. Furthermore, that pair should be the same colour all the way as far as each pair have its own twisting step. – Kondybas Apr 13 '15 at 3:46
  • Sorry wasn't able to reply to your comment above Mark Henderson regarding your picture request due to the 50 reputation thing. I can't also take a picture due to some strict policy but I can assure you of the color coding which as you considered is 11223344 (Wg G Wo O Wbl Bl Wbr Br). Not the usual T568a or T568b which I very much checked a lot too on Google images. And yes they were handmade as I've stated before there was no patch panel. The only part where impact tool was used were on the outlets of the workstations and it is RJ-45 connecting to the switch. Yeah I'm aware of the bad network – user281337 Apr 13 '15 at 8:51
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100 Mbps twisted-pair cabling used only two pairs of four - 1 and 2:

11233244

In your case White-Orange and Blue wires are used as pair, but they doesn't. Untwisted wires are wery sensitive to the interference and signal fading is higher, that is why wrong layout can drive to the various problems.

All modern ethernet chips can do auto-MDX, so there is no necessity to make crossover cables now. But we still have to do proper wiring.

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