# Crossover cable



## v12dock (Apr 12, 2010)

What is the purpose of a Crossover cable?


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## hat (Apr 12, 2010)

It's for directly connecting two computers togeather...

pc1 <---crossover---> pc2


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## v12dock (Apr 12, 2010)

But I can do that with a regular ethernet cable


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## newtekie1 (Apr 12, 2010)

v12dock said:


> But I can do that with a regular ethernet cable



No you can't, unless one of the computers supports auto-sensing, which is rare for a network card in a computer to have.


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## v12dock (Apr 12, 2010)

Be your own DHCP server and tell each computer there IP


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## newtekie1 (Apr 12, 2010)

v12dock said:


> Be your own DHCP server and tell each computer there IP



That won't work if you directly connect two computers, the data still won't get through without a crossover cable.


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## v12dock (Apr 12, 2010)

But a switch or hub would act as a bridge between two computers if you didn't have a crossover cable, correct?


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## freaksavior (Apr 12, 2010)

v12dock said:


> But a switch or hub would act as a bridge between two computers if you didn't have a crossover cable, correct?



yes


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## p_o_s_pc (Apr 12, 2010)

I have 2 computers connected with just a normal Ethernet cable with nothing in-between them..I use if for a server and crunching rig(shares internet with main rig)


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## v12dock (Apr 12, 2010)

Thats what I do. Because my switch is only 100mbit I just connect two computers together with a regular ethernet cable and transfer files at 1000mbit when transferring a large amount of data


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## eidairaman1 (Apr 12, 2010)

Hook up 2 computers directly, 2 routers, switches, hubs directly to eachother.


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## newtekie1 (Apr 12, 2010)

v12dock said:


> Thats what I do. Because my switch is only 100mbit I just connect two computers together with a regular ethernet cable and transfer files at 1000mbit when transferring a large amount of data



All of the modern Gigabit NICs, onboard and add-on, support auto sensing.  So they would not require a crossover cable.  Auto-snesing with onboard cards is still rather rare, but getting more popular, especially among enthusiast motherboards that have built in gigabit.


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## Deleted member 3 (Apr 12, 2010)

newtekie1 said:


> No you can't, unless one of the computers supports auto-sensing, which is rare for a network card in a computer to have.



Auto MDI/MDI-X sensing is part of the Gbit standard, all Gbit hardware should support it.


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## newtekie1 (Apr 12, 2010)

DanTheBanjoman said:


> Auto MDI/MDI-X sensing is part of the Gbit standard, all Gbit hardware should support it.



I thought so, but wasn't sure. Gigabit is still rather rare, though, especially among pre-builts which is most of what I see all day...


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## Deleted member 3 (Apr 12, 2010)

newtekie1 said:


> I thought so, but wasn't sure. Gigabit is still rather rare, though, especially among pre-builts which is most of what I see all day...



It's a standard feature of ICH8 and up. It has been optional from ICH5. So I really doubt it's a rare feature. I'm not sure if any company even bothers making fast Ethernet chips these days at all.


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## newtekie1 (Apr 12, 2010)

DanTheBanjoman said:


> It's a standard feature of ICH8 and up. It has been optional from ICH5. So I really doubt it's a rare feature. I'm not sure if any company even bothers making fast Ethernet chips these days at all.



Rare on a new machine? No.  Rare on most of the machines still in use today? Yes.


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## Deleted member 3 (Apr 12, 2010)

newtekie1 said:


> Rare on a new machine? No.  Rare on most of the machines still in use today? Yes.



Care to back your opinion up with anything that resembles a fact? I just gave you two.


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## newtekie1 (Apr 12, 2010)

DanTheBanjoman said:


> Care to back your opinion up with anything that resembles a fact? I just gave you two.



Well if I had access to the number of complete shit dells/gateways still in service, sure, but I don't so consider it opinion based on experience.  Based on the number of S478 machines I still see on a weekly basis...I'm fairly confident in my opinion.


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## Deleted member 3 (Apr 12, 2010)

Interesting facts those are.





70 million new PC's sold in the US alone in 2008. Add sales of 2009 and Q1 2010 to that and I think we're talking about 2 PC's per 3 US citizens that is newer than 2008 and is very likely to have Gbit ethernet.
I'm guessing your local facts from Indiana don't apply to the rest of the USA or the world.


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## Mussels (Apr 12, 2010)

i'm even seeing nettops with gigabit.


let me put it this way: even if a device is 100Mb these days, its likely going to be new - if its new, its gunna support auto-sensing and thus have no problems with crossover cables.


You also only need one side to support it for it to work - gigabit card on a 100Mb switch? no probs, the card does the 're-wiring' on its end, and alls well.


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## newtekie1 (Apr 12, 2010)

DanTheBanjoman said:


> Interesting facts those are.
> 
> [url]http://www.etforecasts.com/products/ES_pcw4.gif[/url]
> 
> ...



I'm willing to bet they do, when you look around at all the business with completely ancient machines, you know there are a lot of old machines still in use.


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## Deleted member 3 (Apr 12, 2010)

newtekie1 said:


> I'm willing to bet they do, when you look around at all the business with completely ancient machines, you know there are a lot of old machines still in use.



I'm not sure about the USA, but the economical lifespan of a computer at an office is roughly 3 years in my part of the western world. They get replaced after that, even if they still run MS Office just fine. A funny detail however, software lasts far longer. IT departments don't like to migrate large software suits. Thus many still use Windows XP, MS and other large software houses even has extended support on EOL products for large customers.


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## newtekie1 (Apr 12, 2010)

DanTheBanjoman said:


> I'm not sure about the USA, but the economical lifespan of a computer at an office is roughly 3 years in my part of the western world. They get replaced after that, even if they still run MS Office just fine. A funny detail however, software lasts far longer. IT departments don't like to migrate large software suits. Thus many still use Windows XP, MS and other large software houses even has extended support on EOL products for large customers.



Used to be that way, then the economy tanked, and 4-5+ years in the norm for business here.  Shit...I still support Win2000 machines that were bought when Win2000 was new...

Anyway, I'm sure we have taken this thread far enough, we now know what a crossover is for.  To directly connect two older machines that don't support auto-sensing.


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## Deleted member 3 (Apr 12, 2010)

We do? I must have missed that when we went off-topic. Could you repeat it?


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## newtekie1 (Apr 12, 2010)

DanTheBanjoman said:


> We do? I must have missed that when we went off-topic. Could you repeat it?



Haha...ninja edit.


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## Mussels (Apr 12, 2010)

its in hats first post, which has no edits that i can see.


for a more technical answer than was given, tis simple: straight through cables are the same on both ends. so two PC's directly connected would be transmitting to each others transmit wire, and listening on the same wire - one needs to transmit to where the other is listening. Its like holding a phone upside down, you cant listen with your mouth.


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## brandonwh64 (Apr 12, 2010)

newtekie1 said:


> No you can't, unless one of the computers supports auto-sensing, which is rare for a network card in a computer to have.



just set manual IPs on both PCs and make sure you can ping one another then setup sharing to start transfering files.

PC1
IP: 192.168.1.100
SNM: 255.255.255.0
DG: 192.168.1.1

PC2
IP: 192.168.1.101
SNM: 255.255.255.0
DG: 192.168.1.1

start the run then CMD

at command prompt type "ping 192.168.1.101"
if it doesnt find it then close all firewall/antivirus programs on both computer cause they can be a pain.

then once you have ping each other, create the shared folders on each computer that you want to exchange, then create a new shortcut with "\\192.168.1.101" on pc1 and viseversa on pc2 to access each others files.

I did this in iraq when we didnt have thumb drives to transfer movies and games to each others computers. once your done set network back to DHCP to get your IPs back


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## Mussels (Apr 12, 2010)

brandonwh64 said:


> you can without autosensing too. just set manual IPs on both PCs and make sure you can ping one another then setup sharing to start transfering files.
> 
> PC1
> IP: 192.168.1.100
> ...



see my post. running crossover cables (or auto sensing) is REQUIRED  - DHCP is totally unrelated in this case. (using a switch negates the need for crossover cables, but you still need either static IP's or a DHCP server either way)


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## brandonwh64 (Apr 12, 2010)

we didnt use a switch, it was just a plain ethernet cable hooked from one PC to another


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## newtekie1 (Apr 12, 2010)

brandonwh64 said:


> we didnt use a switch, it was just a plain ethernet cable hooked from one PC to another



Then your obvious answer is one of the computers supports auto-sensing, which seems to be less rare then I thought...man I fell like such an old timer... I'm going back to my 10Mbit hub.


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## Mussels (Apr 12, 2010)

brandonwh64 said:


> we didnt use a switch, it was just a plain ethernet cable hooked from one PC to another



well, if it worked, that means at least one machine supported auto sensing.

Transmit wire ------------- Transmit wire
Receive wire -------------- Receive wire

^ normal cable. Get the idea? if you're talking to a mouth and listening to an ear, nothing happens.



```
Transmit wire ------   ------ Transmit wire
                     X
Receive wire -------  ------- Receive wire
```
while its done at the END of the cable and not in the middle, you get the idea - you have to _cross over_ the pairs, so that each end is receiving what the other is transmitting


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## brandonwh64 (Apr 12, 2010)

well i would say your right cause all of the laptops i used to do this with were very new and my ABIT board had gigabit lan so im saying it probly did too. it should be a new standard with ethernet cards


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## Mussels (Apr 12, 2010)

brandonwh64 said:


> well i would say your right cause all of the laptops i used to do this with were very new and my ABIT board had gigabit lan so im saying it probly did too. it should be a new standard with ethernet cards



it has been a standard since gigabit came out. While it may be optional with 100Mb devices, i'd assume that any made these days will support the standard.


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## brandonwh64 (Apr 12, 2010)

Mussels said:


> it has been a standard since gigabit came out. While it may be optional with 100Mb devices, i'd assume that any made these days will support the standard.



yea! so i stand corrected! the laptops probly had autosensing


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## v12dock (Apr 12, 2010)

Well I have done it on dells from 2001 but they also had 1Gbit


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