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Crossover Cables
joshua Oct-13-01 04:37 PM
I have a small 4 PC network at home. I only have an old 10mps HUB (boca) and I'm needing more speed. (backing up large files from one PC to the other) So, I was going to make a crossover cable between 2 and just do it that way. Instead of making one, I wanted a converter for a standard straight through cable. I took a modular inline RJ45 connector and crossed the pinout (1-3, 2-6). I get a link light, and, if I put this connector on a crossover cable, and connect from computer to HUB, it works. (so the connector does convert back). Anyways, said all this just to make sure you approve of the connector. (never heard of doing this before)

I've never used a crossover cable, and I'm not quite sure how to set it up. I connected it between 2 computers, set IPs to 192.168.0.x, cold booted, and it doesn't work. Can't see either computer, if I ping, I get a 50-100% packet loss? I've tried other cables that do work on my current network (from PC to HUB). All this is on my little modular connector... could that be a problem? I do get 100mps link (running Win2000 on one, and Win98SE on the other)

Any help would be greatly appreciated!

By the way, I was searching the Internet for crossover cables when I stumbled upon your site... LOTS of information. I love it! Sending the link to many friends! Thanks!


1. RE: Crossover Cables
lbyard Oct-13-01 05:08 PM
In response to message 0
Oh, I have indeed heard of it before. And now you see from first hand experience why I donít recommend it. It is more involved than DC wiring. For one thing, 100 MHz CAT 5 cabling should not be untwisted at the ends, etc. for more than ĹĒ. You have come to the right place to learn how to make a crossover cable (http://duxcw.com/digest/Howto/network/cable/cable1.htm) that will work (http://duxcw.com/faq/network/catest.htm). The network configuration (http://duxcw.com/digest/Howto/network/net2pc/intro.htm) for connecting two computers together with a crossover cable is exactly the same as connecting them together with two straight-thru cables and a hub or switch (http://duxcw.com/faq/network/hubsw.htm). Larry

2. RE: Crossover Cables
joshua Oct-13-01 05:41 PM
In response to message 1
Yes, I know how to make one, but don't have the tools. I have a laptop and would prefer to have some small way to carry a crossover cable instead of having to carry two cables (ie. the converter). But you are saying because of this untwisting, I'm getting the heavy packet loss? That makes since. Hmmm.... never knew network cables were so sensitive! Thanks.

3. RE: Crossover Cables
joshua Oct-13-01 05:42 PM
In response to message 2
Now that I think about it.... why do companies make RJ45 modular inline connectors? They are untwisting the wires, and just that shouldn't let the connector work???? That doesn't make since!

4. RE: Crossover Cables
joshua Oct-13-01 05:45 PM
In response to message 3
(sorry for multiple replies)

I can't belive this! You are so right! I took the connector apart, and twisted it about 2 or 3 times, and now I'm only getting a 25% packet loss and sometimes none!!!??? WOW! (But still getting some loss... since it does go through some straight part)

So, when actually making cables, it is best on the ends to leave as little as posible untwisted because it caused this! Thanks again!

6. RE: Crossover Cables
lbyard Oct-13-01 06:14 PM
In response to message 4
Yes, perhaps someday everyone who tinkers with networks will realize "the importance of the word 'twist' in making network cables which will work," which I spent a lot of time trying to illustrate at the bottom of http://duxcw.com/digest/Howto/network/cable/cable5.htm. If you are getting 25% packet loss, you have a bad cable that could possibly cause file corruption if used long enough. Ethernet correct code is a very robust CRC process, but it isnít 100% perfect. An error could pass through without detection/correction. The more errors there are, the more likely one will get through. Larry

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