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Auto MDI/X for Gigabit Ethernet 1000BASE-T

Hello - I have a question on the Auto MDI/X feature on 1000BASE-T Gigabit Ethernet Copper.

Does it work using same concepts as in Fast Ethernet 100B-TX? In

100BASE-TX it used 2 pairs whereas in 1000BASE-T used 4 pairs. ?

For Fast ethernet supporting Auto MDIX(when Auto Nego is Enabled), the PHY switches its transmitter to RD+- and its receiver to TD+-, alternatively till a link is establised with the link partner.

How does it work for Gigabit Ethernet copper 1000BASE-T ? Is it similar

Any pointers suggestions would help .

Also please if you could let me know the IEEE specifications Clause which defines this for Fast ethernet and Gigabit Ethernet Copper .

thanks and Best Regards Kott

Reply to
Kott
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1000baseT transmits and receives on all four pairs at the same time. The result is that there is no switching of the transmit/receive but only the need to identify which pair each is coming in on.

As I understand it, as long as they are paired right, it will work with any transmit pair connected to any receive pair. It at least is supposed to work straight or with the (1,2) and (3,6) pairs crossed. My crossover cables also cross (4,5) and (7,8) but I don't know that others do that.

-- glen

Reply to
glen herrmannsfeldt

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