Ethernet wire config?

[dcongram]

Wiring an RJ45 'backwards' is a Cross-over cable. Used for connecting one hub/switch to another (when no 'uplink' port is available).

Or connect 2 computers directly

Now there are auto-sensing switches that do the X-over.

[j3r]

If you are implying that you can use any color scheme, absolutely you can do so...
The color code has nothing to do with Ethernet, its to make everyones life better
when running cable and troubleshooting diff wiring..(EIA/TIA standard not IEEE)

Yeah, that's what I was trying to express. (Of course, you can't use *any* color scheme. For example, running two signal lines over one pair (as opposed to running one signal and one ground over one pair) will cause your cable to not work (although you *may* get a link light).

As a side note, you can use cat5 to make really long (~50 foot) serial cables for cheap.

[gunit0072003]

J3r,
Yes you can use any color scheme..available to you within the UTP wire,,as long as for straight thru cable what ever colors you used for pins 1,2 3, and 6 on one RJ45 connector, they are the same on the other end,,,And same holds true for cross over cable,,crossing the appropriate pins.

I dont know what you are referring to ?????

"running two signal lines over one pair (as opposed to running one signal and one ground over one pair) will cause your cable to not work (although you *may* get a link light).

cheers.

p.s
dcongram ,
the reason why I asked that question is because "backwards" can also be referred to as a roll-over cable, where the color scheme of pins 1---8 on one RJ45 are exactly backwards/opposite of pins 1--8 on the other end.....(This is used by Cisco, their pinout for their console cable)

[dcongram]

gunit0072003......the Cisco roll-over cable is interesting.

So....the different Twists/per/inch/per colour pair don't affect the propagation of signal in Cisco ? Or is it a short cable for console only where distance doesn't matter ?

[gunit0072003]

short cable yea,,doesnt matter,,can even be cat1 also

[j3r]

I dont know what you are referring to ?????

"running two signal lines over one pair (as opposed to running one signal and one ground over one pair) will cause your cable to not work (although you *may* get a link light).

Sorry, being unclear again. So, each pair is really one data line. (A pair is color x and colorx/white.) Sending a signal down one one wire of the pair will induce a large signal in the other wire. However, due to the differing twist rates of the different pairs, it will not induce a large signal in any of the other pairs. So, if you wire up your cable with one part of a pair hooked up to one part of a data line, and the other part of a pair hooked up to the other part of the data line, your cable will not work. As example, say your using 10bT, and you hook up:
tx tip to orange
tx ring to green
rx tip to orange/white
rx ring to green/white
The induced signals will cause your tx signals to appear on both the tx line and rx line, and your rx signals to appear on both the rx line and the tx line.

This is very much in the weeds, and anyone who just wanted to save $ on ethernet cabling should've stopped reading a long time ago.

Here's an interesting post explaining more about why some miswired ethernet cables work, and some don't. Also very useful if you're trying to make cheap, long serial cables from cat5.

http://www.tek-tips.com/gviewthread....575/qid/416325

[gunit0072003]

I got you now,,very good...

cheers