100base tx vs 1000base tx fundamental question

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Just want to know the premise behind:

1) Why does 100base tx us 4 wires (2 wire pairs)? In other words why do you need 2 RX and 2 TX

2) WHy does 1000base tx us 8 wires( 2 wire pairs)?

Thanks
 

1000BASE-TX doesn't use "8 wires" (4 pairs) and I guess you rather mean 1000BASE-T, which is upwards compatible to standard 10/100 MBPS ethernet cabling.. See a brief explanation of it's operation:
Gigabit Ethernet - Wikipedia, the free encyclopedia

As the Wikipedia article shows, 1000BASE-T doesn't use dedicated RX or TX pairs. It's transmitting over 4 differential pairs with a Hybrid separating both directions. I don't know if you are familliar with the basic theory.

100BASE-TX uses classical RZ signaling with separate RX and TX pairs. In this regards, it's identical to 10BASE-T.
 

FvM said:
1000BASE-TX doesn't use "8 wires" (4 pairs)
Click to expand...


**broken link removed**




The article I am reading suggest that 1000baseT (Gigabit ethernet) uses all wires. There are 8 wires in a cat 5 cable.

So am i interpreting the article incorrectly?
 

Did you understand, that recent ethernet (as most high speed data transmission methods) uses differential signaling. Two wires form a differential pair. Both articles, Wikipedia and your linked "Hardware secrets" tell about 4 pairs used with 1000BASE-T, there isn't any contradiction.

As I already told 1000BASE-TX is a different standard without much practical importance. The Wikipedia article mentions the popular confusion of 1000BASE-TX with 1000BASE-T, which also appears in your orignal question.
 

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