Network connection problem

[iago]

I'm having a strange (and annoying, since I hate the computer I'm using) problem with my network.  

It worked fine as late as this afternoon, but it's not working now.  I have two computer that are important here, MAIN and LAPTOP.  MAIN has 2 network cards, and LAPTOP only has one, and they are generally connected to each other with a crossover cable.

Awhile ago when I turned on my laptop, Windows XP gave me the message, "Network cable unplugged", so I fiddled with it, sticking the cable into both of my network cards, to no avail.  On one of the cards, I would get a connection flash on and off every few seconds, and on the other card I would get no connection.  The light on the back of my main computer indicating a connection stayed dim on one card, and flashed every few second on the other while connected.

I tried changing to my 10-foot cable, which I bring with me with my laptop.  I get the exact same problem, so I was worried it was my laptop's NIC.  Then I tried plugging my laptop straight into my DSL modem, which is done with a straight cable, and, to my surprise, that worked.  The DSL modem is also working on MAIN just fine, in either of the cards.  

I was using my laptop with my short crossover at my friend about 10-minutes before I couldn't get it working at home.

That's about all the information I have, besides banging my head against the walls.  Now I'm going to go play a SNES rom offline till I go to bed, since that's about all I can do with no internet

Thanks to anybody who actually read this whole thing!
-iago

[Adron]

Since you've tested all three cards against the DSL modem, it sounds like perhaps your cross-over cable is broken?

It could also be some kind of incompatibility between your laptop's and your main's duplex settings. Try specifying half or full duplex and the right speed on both ends.

[iago]

What is a duplex setting, and how do I find them?

The weirdest thing is that I've been networking them like this for months, and nothing like this has happened, and I have two cords neither of which work!

I'll test the cord at my friend's in the evening to find out that for sure.

I've changed absolutely nothing on either of the computers today that could possible affect this.  I haven't changed drivers or settings or anything.

[Adron]

Usually you find them in the advanced properties for the network card. In my case I have "Connection-Type" set to "Auto-Negotiation" and "Flow Control" set to "Hardware Default".

If they are set to auto-negotiate, then perhaps the card could be confused and stick to whatever it auto-negotiated with your friend's computer.

If it wasn't for that both cards work just fine with the dsl modem, I'd suggest checking the cards/connectors so you don't have a bad connection - dirt, bent pins, whatever...

[iago]

Both computers had flow-control set to auto, so I set them both to 100tx half.  Now I'm not getting the error, and the light on the back of my NIC is blinking, but the computers still can't see each other.  I can't ping either of them.

I'm trying to fiddle around with my connection settings, but to no avail.. I'm getting really tired of this, and I doubt I'll be awake much longer.  

Anyway, thanks for your help, I might be able to figure it out from here! :-)

[Adron]

It's blinking when? All the time, or just when you send data? Check that you don't have the wrong IP settings now?

[iago]

Well, I'm on my laptop at my friend's, using a firewire connection (400mbps!).  I'm pretty sure it's a hardware problem, but it's not really a big deal since I have a USB NIC I can use, since I can get the drivers now.

[Thing]

I think your desktop and your laptop broke up with each other.  One of them needs to buy the other some flowers or something.

[iago]

Well, I went to the cottage for 4 days, and brought my laptop with me.  That's the longest they've ever been apart.  Do you think that coule have contributed to it? :-(

[Amphetamine]

Move a nic to the last pci slot opn the mobo and reset configuration data. Reinstall the driver (automaticly?) and try again. If it doesn't work get a HUB / Router and try networking them with RJ-45 cable (straight through)

[Camel]

Unless the crossover cable is fucked up, which it obviously isn't, there's no reason to invest in a hub or router. All a hub does is act as a crossover cable with more than two ports. A router is the same, except basicly serves as a gateway between the network and the internet.

[Amphetamine]

for testing purposes

[Skywing]

Unless the crossover cable is fucked up, which it obviously isn't, there's no reason to invest in a hub or router. All a hub does is act as a crossover cable with more than two ports. A router is the same, except basicly serves as a gateway between the network and the internet.

You left out a whole lot of important information.

Hubs are "dumb" devices.  They do not reroute or otherwise modify messages, and just forward them to every computer on the hnetwork.  However, unlike a crossover cable, a hub will boost the signal and extend the range of your connection.

Switches perform the same functions as hubs, with the exception that they route Ethernet packets to their proper destination, instead of broadcasting them to everything connected.  Hence, picking a hub for a large network is a bad idea.

Routers typically perform protocol-specific (i.e. IP, TCP, UDP) routing and network address translation, in addition to the functions of a switch.

[Thing]

Switches perform the same functions as hubs, with the exception that they route Ethernet packets to their proper destination, instead of broadcasting them to everything connected.

Another thing to note is that switches operate on different layers of the OSI model.  A brief overview can be seen here: http://www.blackbox.com/tech_docs/tech_overviews/switching_overview.html