What's the difference between a crossover ethernet cable and a straight through one?

[soarlow]

I need to connect two laptops together to do a network install of windows, but it says to use a ethernet "crossover" cable, is that the same as the ethernet CAT5 cable that goes from your NIC to your Rogers cable modem?

I heard there is a "straight through ethernet cable", what's that?

Trying to do this:

http://blog.ryantadams.com/2008/02/0...nd-windows-pe/

[Sprite09]

I used crossover cable to connect 2 computers together through lan ports. I heard some of the newer lan chips don't even need crossover cable and can use a straight through cable directly between 2 computers. The straight through is for connecting computer to router, modem. Ordered a 25Ft cable from monoprice to save me time making my own from a short cable that was not really long enough.

[movieman]

A crossover cable swaps some of the wires over so the transmit signal at one end goes to the receive at the other.

However, they're generally not required anymore as ethernet chips will usually auto-detect the cable type and adapt as appropriate.

Edit: Actually, wikipedia claims you may still need a crossover cable to connect two PCs without a switch in between, but I'd try it with a normal cable first before spending any more money:

http://en.wikipedia.org/wiki/Ethernet_crossover_cable

[soarlow]

so I have a bunch of ethernet cables, I think they're all for connecting LAN to router/modem... they wouldn't be crossover cables would they? crossover cables are not as "common" right? where can I get one cheap to connect my 2 laptops without buying online?

[soarlow]

my 2 laptops are kinda old though, T41 centrino era... 2004? would I be able to connect two laptops without buying a special crossover ethernet?

[movieman]

Without checking the cables (e.g. comparing the cable colors at each end) you won't be able to tell; I'd try them and see if you can find one that works. Plugging the wrong type of cable in shouldn't cause any damage.

[mcplar]

I would try one of those that you have first, as others said.. you might get lucky!

I would try TSCC, or possibly a mom & pop computer shop might be able to make you one!

[soarlow]

any way I can use my Talkbroadband VOIP box from Primus or a wireless router as that intermediary "switch" thing? I'm not really sure what a switch is, but I assume it's like a router?

so laptop to router to laptop, would that work? (avoiding the whole crossover cable thing)

[number8888]

Nope. The cables are totally different and have different purposes. Cross-over is for PC to PC connection, while straight-through is for PC to router/switch type of connections.

Technically the cable itself looks the same but the internal wiring is different. Simply put, in a straight through cable, the pins 1-8 on one side would correspond to the same order on the other side, so 1-8 <-> 1-8. In a cross-over cable cable the pins on the other would be reversed on the other side, so 1-8 <-> 8-1. So if you use the wrong cable, then data would be sent down the wrong pin when it gets to the source.

For your situation, if you have a router you can try to hook both computer up to it, have the router assign them IP addresses, and continue from step 9 in your link. Bascially this means you don't have to manually assign an IP. Not sure if this will work but can try it out if you don't have a cross-over cable.

Found the diagrams below which I hope would help.

Straight-Thru


Cross-over

[soarlow]

so unplug my wireless router from the internet connection (cable modem) , and plug both laptops via regular CAT5 ethernet cables to the router and they will be able to talk to each other?

[number8888]

However, they're generally not required anymore as ethernet chips will usually auto-detect the cable type and adapt as appropriate.

You are right, but I think auto-detect is generally a feature on the router ports and no on the PC ethernet ports. Then again it's not someting I pay attention myself.

[soarlow]

You said "have the router assign them IP addresses".... how do you do this?

Also, one laptop is functional with windows and everything, the other computer doesn't have any OS (which is the whole point of all this, I'm trying to put an OS on this laptop via this networking business) Can it still assign it an IP address?

[number8888]

so unplug my wireless router from the internet connection (cable modem) , and plug both laptops via regular CAT5 ethernet cables to the router and they will be able to talk to each other?

Yes, because they are already on a network in this case. I don't even think you will need to unplug your modem for this because router will assign IP's irregardless of internet connection.

Where the link said to manually set your IP to "192.168.1.5", you would be using the router assigned IP instead. Your second com should be able to see your first one. At least that's what I would expect.

[soarlow]

how do I know what the router assigned IP is? where can I check it?

[number8888]

You said "have the router assign them IP addresses".... how do you do this?

Also, one laptop is functional with windows and everything, the other computer doesn't have any OS (which is the whole point of all this, I'm trying to put an OS on this laptop via this networking business) Can it still assign it an IP address?

By default network routers would assign IP addresses to each anything that is part of the network. It's how each machine communicate with each other. They should be in the form 192.168.xxx.xxx

And I am just wondering if your 2nd laptop lets you boot from USB? That would be so much easier than all this networking stuff.