Eric Jahn wrote:
>On Fri May 28 2004 2:13 pm, Backward Thinker wrote:
>
>
>
>>If you're in a pinch you can DIY: switch pins 1/3 and 2/6 on one
>>end of your straight patch cable... but personally I wouldn't
>>bother unless you can't find any crossover or they want like twice
>>as much $ :).
>>
>>
>Thanks, I think I'll try that. This is rhetorical question, but why can't
>there be just one type of cable for both patch and crossover? It still just
>uses IP over Ethernet...
>
>
Try not to confuse network transport layer 3 (IP) or data link layer 2
(ethernet frames) with physical layer 1 (ethernet 10/100baseT).
Electrically, two of the wires are treated as a "transmit" pair on one
side of the cable (tx-/tx+), and the "receive" pair (rx-/rx+) on the
other side of the cable. As both sides need to transmit and receive
data, you have two pairs of cables to this end.
If two machines try to transmit on the same pair and receive on the same
pair, they cannot communicate - thus the need for a "crossover" cable.
- Ian
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