RJ-45 Cables

What's the difference between Patch and Crossover cables?

All replies appreciated

Jinky




Me-GT

On Sun, 31 Aug 2003 12:57:26 +0100, "Me-GT" <(E-Mail Removed)>
wrote:

>What's the difference between Patch and Crossover cables?

A straight-through or patch cable is used when connecting
a PC to a hub, or when connecting a hub to another hub using the
UPLINK port.

A cross-over cable is used when connecting two PC's directly, or
linking two hubs port-to-port, without using an UPLINK.
--
"Hello Kitty realized that there was only one way to resolve this messy
issue: an explosive orgy of mindless violence punctuated by
a few snappy one-liners." (J. Austin Wilde, 'The Day Sanrio Died')

"Me-GT" <(E-Mail Removed)> wrote:

>What's the difference between Patch and Crossover cables?

If you are accurate there actually is none.
Most people use the term "patch cable" for a straight through cable
while actually a patch cable could be a crossover cable too.

The difference is very simple:
If you have two sending stations which are also two recieving stations
and they communicate over wires, they both need a sending wire and a
recieving wire.

Station_A[TX]---------sending A to B---------------------[RX]Station_B
[RX] [TX]
\_______________sending B to A_________________________/

[RX] = Reciever
[TX] = Transmitter

Since network connectors of the RJ45 type have their [RX] and [TX]
normally at the same pin-out the [RX] of Station_A and the [RX] of
Station_B would be connected by a straight through cable as well as
Station_A's [TX] and the [TX] of Station_B.

Station_A[RX]---------sending A to B---------------------[RX]Station_B
[TX] [TX]
\_______________sending B to A_________________________/

[RX] = Reciever
[TX] = Transmitter

The recievers would listen to eachother, but they cannot send
anything. Also the senders would send to eachother but none of them
can recieve. It would be like holding the phone with the speaker to
your mouth and the microphone to your ear.

I think you already guessed now what a crossover cable would be.
Absolutely right! The recievers wire and the senders wire are simply
crossed.

Station_A[RX] _______sending A to B_____________________[RX]Station_B
[TX] \ / [TX]
\ X /
\___/ \_________sending B to A_________________________/

[RX] = Reciever
[TX] = Transmitter

Ok, that's a bit simplified, because there are two wires for [TX} and
two for [RX] but I think you understood the difference now.
Actually there may be a port marked with X or a switch with positions
marked with X and || on such a device as a hub, a switch or a router.
The X tells the port is crossed internally and the switch allows you
to change from internally crossed port to a straight through port.

I hope everything is clear now.

regards
André