View Full Version : Occasional network "unplug"

16-12-2002, 10:30 PM
i have a laptop and a desktop. Laptop is a 3Com 100/10 Mini PCi card win2k pro and the desktop is a 3Com 10 win95. this cable used to work - Cat5 crossover. Previously had problems and fixed when I switched ends and worked fine. Now.....

I can browse, copy etc.... but with great difficulty.
Such that a lot of time it connects and disconnects every few seconds thus when i am copying it stalls and starts repeatedly.

When I connect the cable both machines has lights (LAN card) if I change ends of the cable desktop has no light but laptop still has.

I have also tried changing LAN card in the desktop to no help. My laptop works fine at the workplace via straight cable to the wall.

Can I rewire the cable? To determine which end it is. As one way the cable have lights on both machines. Switch ends the desktop have no light. So.... would it be true that its this end that require rewiring??


17-12-2002, 08:24 AM

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Hope this Helped


17-12-2002, 08:30 AM

I doubt that you would need to rewire the cable as Crossover cables are wired in a special way so that you can use them without a hub

Have you got a firewall installed on one of the machines that could be interefering with the connection??

What surprises me is that one way the cable works fine, and then when it's used the other it has problems.

Have you tried using a different crossover cable to check whether there is something wrong with your current cable or whether it is more than that?


17-12-2002, 08:31 AM
Ah bugger... That top post was supposed to go to another thread...

Read the post below for the information relating to this thread - sorry


17-12-2002, 09:14 AM
i have exited all my firewalls. does not help.
do u think the wiring is faulty?? so i rewire??
no i have not tried another cable
i have tried changing lan cards on desktop to no help.
laptop works fine at work via lan and sharing internet with cross over cable with another laptop.

if u connect it one way - desktop has no light, laptop has. (no connection)
switch around - both have lights. (yes connection)

while it does get a connection ... it starts and stalls repeated every second. v unreliable.


17-12-2002, 09:36 AM
Is it a commercially made cable?
It sounds like its not correct, or is not using the correct core pairing.
It is critical to use the correct lay of cores.

17-12-2002, 09:40 AM
all i know it is a white cable (cream white?)
UTP crossover Cat5. Bought for domestic use ... the ones for home use. $15 ones....

i bought when i had a 10BaseT in laptop and desktop.
since i have changed to a newer laptop with a 100/10 network.

perhaps its faulty wiring?? should i rewire it?


17-12-2002, 09:46 AM
I wonder if its up to the task of 100 Mbit.
Cables that work at 10 Mbit can be problematic at 100.

The fact that the lights are not both working would suggest to me that the cable should be tossed.

Dont just reterminate it, as the cable itself may not be able to reliably carry 100 Mbit. Get a new cross-over cable.

17-12-2002, 09:58 AM
Goto DSE and grab a cross over cable and try, if it works, keep it otherwise return it within 7 days :)

31-12-2002, 07:57 PM
I bought one of DSE's Cat5e crossover $12 cables today. Same problem. Since its a mini pci card for laptop - I called 3Com he basically said check the manufacturer - the problem is I bought an OEM product from a shop (not 'the' shop). Its a 3Com 56k 10/100 Lan 3CN3AC1556 OEM, the consumer product is 3CN3AC1556B.

If it works w a straight cable in the office at full speed (no unplugs). Why should it fail at home with a crossover?? I tried to change the setings to a 10BT half duplex and fulll duplex (as by 3Com). Was better than auto neg... but times it still unplugged like every 4 seconds, an 4.8MB MP3 file took 60sec. 75MB folder took 43min and since I have cancelled it.

Would u suspect its the desktop?? I have tried 2x PCI LAN cards inside it. Together with my cable and a new DSE cable (today).

I will try laptop with another (3rd) PC later using cross over cable - to determine if its my laptop or my desktop the problem lies with.

31-12-2002, 07:59 PM
reason i say I chose 10BT is .. the laptop is 100/10 card.
desktop has a 10 card only.