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Home » Forums » Forum Archives » Networking and Internet Sharing » Topic # 1791

Flashing hub lights & connection problem
markpace Mar-27-02 09:29 AM
Hi all

I have laid approx. 75m insulated CAT 5 cable to connect a computer at the other end of the workshop to our office network hub (UNEX Nexhub 8 port 10/100M).

I have put RJ45 connectors on both ends of the cable and they are both wired exactly the same (straight through).

When I plug the ends in (one in the computer and the other in a port on the hub) the light on the hub for that port goes green (for 100m connection), but then flashes orange twice (orange = 10m), goes off, and then repeats. When the light goes off, the ACT light flashes briefly each time. (Does this mean the hub is trying 100m and then tries 10m and as that fails it rests and then tries again continously?)

I guess this means that there is some sort of connection happening - just a bad one for some reason.

I have tried putting new RJ 45 plugs on and double checking etc (as well as another network card and trying other ports on the hub) and still same problem.

I would appreciate any ideas on the sort of problems that could cause this bad connection and any potential solutions.

Thanks for your help

Mark.


1. RE: Flashing hub lights & connection problem
lbyard Mar-27-02 12:48 PM
In response to message 0
Have you read http://duxcw.com/digest/Howto/network/cable/cable1.htm and looked-over http://duxcw.com/faq/network/index.html?

>Does this mean the hub is trying 100m and then tries 10m and as that fails it rests and then tries again continously?)

All of the ones I've seen with a 10/100 LED... if it's 100 it stays on solid most of the time once the handshaking is done. That is a long leg. It has to be done right with the correct cable and plugs or it is not going to work at 100. I've had to do some cables more than twice. Do ony one end at time and test. Read (or know) the first article or you don't know what you are doing, to put it bluntly. Larry


2. RE: Flashing hub lights & connection problem
markpace Mar-28-02 04:01 AM
In response to message 1
>Have you read
>http://duxcw.com/digest/Howto/network/cable/cable1.htm and
>looked-over http://duxcw.com/faq/network/index.html?
>

I had already checked the how to network cable first article.

Just got a question.

I am using foil shielded cable with a drain wire. I know the wire should be earthed - but is this essential or just recommended?

mark.


3. RE: Flashing hub lights & connection problem
lbyard Mar-28-02 02:44 PM
In response to message 2
I have not worked with shielded twisted-pair. But I would think that it could be causing a problem with a cable that long. I donít now about shielded twisted pair, but one does not ground the shield of coax thinwire Ethernet cable at both ends because it can setup a dangerous ground loop condition. Be sure that cable has a characteristic impedance of 100 ohms. If it has a characteristic impedance of 150 ohms (IBM token ring cable) it probably wonít work at that length. I didnít say DC resistance. Larry

4. RE: Flashing hub lights & connection problem
Shaith Mar-30-02 10:59 AM
In response to message 0
You mention that you have it wired straight-through. I wonder HOW - if you just have the wires paired together (O/OW, G/GW, B/BW, BR/BRW) you'll wind up with transmission problems as you're actually changing the pairing used for data.

Try wiring it like this:

1 Orange/White
2 Orange
3 Green/White
4 Blue
5 Blue/White
6 Green
7 Brown/White
8 Brown

Do this on both ends. Should fix your problem up provided your cable isn't cut somewhere, but the problem you describe screams miswire.


5. RE: Flashing hub lights & connection problem
lbyard Mar-30-02 01:15 PM
In response to message 4
I don't know why you are doing this with text when pictures are available on this site at http://duxcw.com/digest/Howto/network/cable/cable6.htm. Larry

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