Network Cables Online Blog    

Q. I just found your web site and i thought that it was very informative, but i could not find any thing on the difference between stranded and solid cabling, could you tell me what the difference between them is? (I think stranded is used as patch leads and solid is used as a connector between the patch panel and the wall outlet).
A. You are correct, stranded cable is used for patch leads because it is more flexible than solid copper. The solid cable is used in the fixed part of the installation, ie. the cable between the patch cabinet and the wall outlets. Solid cable has better performance characteristics than stranded and it is cheaper to make.

Q. Thank you for your help, it was very useful. One other thing you could help me with, is the way that the solid and stranded cable are wired up different? because i know that you can get RJ45 plugs for solid and stranded cable (i know how to wire up stranded cable to a RJ45 plug), if so then how is the solid cable wired up to the RJ45 plug.
A. The colour codes are the same for solid and stranded cables, the difference is in the IDC (insulation displacement connector) in the RJ45 plug. Because the cores are different the contacts have to be slightly different to ensure a good contact is made.

Q. We have a small Pier to Pier network setup with 13 systems and one printer connected to 2 eight port hubs. We are having all kinds of instability with the network. A station might see all the other stations on the network but they can’t see him or visa-versa. Sometimes it will appear and other times not.
When we made the cables for the stations, we used cat 5 cable (4prs) with the following wiring:
Pin 1 wht/org, Pin 2 org/wht, Pin 3 wht/grn, Pin 4 grn/wht, Pin 5 wht/blu, Pin 6 blu/wht, Pin 7 wht/brn, Pin 8 brn/wht.

We tested them using a TBase cable tester, and they passed just fine. Looking at your diagram for correct wiring, it looks like you have some colored wires in different locations, but it is still pin for pin. Is there a reason why ours would be causing our problems?

A. Regarding your question on RJ45 pinouts, I would say that you are probably experiencing crosstalk problems.

The reason is this, Ethernet uses pins 1 & 2 and 3 & 6 on 10/100BaseT networks (I know it’s a funny way to do it but thats how it is!). One pair is used for transmit and the other pair for receive, so pins 1 & 2 at one end will connect to pins 3 & 6 on the other end and vice versa. In the correct wiring configuration each signal path (transmit or receive) is on its own twisted pair of wires, the twists help to eliminate crosstalk. With your wiring, pins 3 & 6 are split between the green and blue pairs making them susceptible to crosstalk (or noise), this also gets worse when using higher speeds (100BaseT or Gigabit Ethernet).

The reason your tester didn’t pick it up is because it only tests for continuity, shorts, crossed pairs etc. (not split pairs) you would have to use a scanner (like the Fluke DSP4000 or MicroTest OmniScanner) to find a split pair.

How can I tell if a cable is a crossover or straight through?
Q. I currently have 2 PCs, one running windows xp and one running windows 98 which I would like to network together using the XP machine as the host. I have 2 rj45 ethernet cards and a 10 metre cat 5e twisted pair cable.
Is there any way to tell if I have the right cable as my computers aren’t communicating and I have tried every other troubleshooting resource, and the only conclusion I can come to is that my cable is not a crossover type.
Any advice would be GREATLY appreciated!

A. If you hold both of the RJ45 connectors side by side and look at them from the bottom (ie. the clip is away from you) you can make out which colour is connected to which pin. The pins you are interested in are (from left to right) 1 & 2 and 3 & 6. If they are the same either end then it is a straight through cable, if pin 1 (usually orange/white, but not necessarily) is connected to pin 3 at the other end and 2 is connected to pin 6 (and vice versa) then you have a crossover cable. If you look at the testing page of the Network Cabling Help website, about half way down there are some pictures of the pin outs for RJ45 connectors. The ‘crossed pair’ image is actually the correct wiring for a crossover cable and above it is the correct wiring for a straight through cable. If you have a straight through cable then it won’t work without a hub, if pins 1 & 2 and 3 & 6 are crossed over then the problem lies with the way the network is setup.

Cat 5 crossover cable?
Q. I have been looking at your site and it was very helpful.
I’m trying to connect two computers with a cat 5 crossover cable. The cable that I received in the mail was crossed correctly, but it was also crossed at 4 &5. My question is will this cable work by just joining PC to PC without any hubs or anything else. I bought the cable from an individual.

A. If you are using it for 10BaseT or 100BaseT Ethernet then the wiring should be 1 to 3, & 2 to 6
Pins 4 & 5 aren’t used on 10/100BaseT Ethernet systems so it should be OK. If you are planning to use Gigabit Ethernet or Token Ring then it won’t work.

Cable length limits?
Q. I know that cables have restrictions on distance, but I really would like to know why those limits are for each cable. E.g. Why is Cat X cable limited to 100m, and thinnet 185M etc. I have just accepted these values but have been asked why and I do not know a technical enough answer as I have never been a cabler. I could not find this on your site and was hoping it might be added or if you could email me back with why. Thanks.

A. The length limits are not for the particular cables as such, they are for the type of data signal that they carry.

Let me try and explain!

Thinnet (RG58 coax) was used for 10Base2 Ethernet, at 10Mbps on RG58 coax Ethernet can reliably operate upto a distance of 185m. The native cabling environment of the AS400 is Twinax and the standard operating speed is only 1Mbps. At this speed it has a maximum distance of 1800m, however, if Cat 5 forms part or all of the link the distance can drop to between 36m and 364m.

So for a proprietary network such as Thinnet, the distance is set at the maximum length that the signal will work reliably at a given speed over a given type of cable. So far so good!

Now, when we talk about Cat 5, 5e, 6 etc. these are cabling ‘Standards’ which define a method of connecting all types of networking protocols, over a cabling system that uses a common media, common connectors and a common topology. So the length limit was arbitrarily set for the worst case scenario. 10BaseT may well work on Cat 5 for 150m but ATM, AS400, Token Ring etc. may not, and because a structured cabling system has to work for all networking methods, a limit had to be set.

I don’t think I have explained this very well but I hope you get idea. Incidentally, I have heard talk of the length limit being dropped from the standards as it is the overall Attenuation to Crosstalk Ratio which determines a cables ability to transmit a signal successfully, and not the length of the cable. If anyone can elaborate on this point please let me know.