auto-crossover - auto-MDI/X capability of ethernet NIC

While googling for info about crossover cables, I found a page which says
"Most later Macintosh computers are able to use either a straight-through
Ethernet cable or a crossover Ethernet cable automatically through the use of
Auto-Medium Dependent Interface Crossover (Auto-MDIX)"

So now I'd like to find a document that lists Auto-MDIX status for the
ethernet chips used with Linux, or to gather the necessary info to put
such a list together: it's a significant feature, worthy of
consideration when deciding which NIC/mobo to purchase. Some grep-ing
of linux-2.4.25/drivers/net/ found hits in e1000/e1000_hw.c, but that's
all. Google found a for-sale msg from 1996 describing the feature on
Intel EEPro 10/100 cards way back then. If you know for sure that a
specific chip has auto-MDI/X, please post a follow-up. Is software a
factor, or is this negotiated entirely at chip level?

On Tuesday 02 March 2004 12:39 pm, ttsp uttered these immortal words:

> So now I'd like to find a document that lists Auto-MDIX status for the
> ethernet chips used with Linux, or to gather the necessary info to put
> such a list together: it's a significant feature, worthy of

I make sure it's a feature of any switch I buy then I don't have to worry
about what NICs or cables I'm using.

--
Andy.

ttsp wrote:

> While googling for info about crossover cables, I found a page which says
> "Most later Macintosh computers are able to use either a straight-through
> Ethernet cable or a crossover Ethernet cable automatically through the use of
> Auto-Medium Dependent Interface Crossover (Auto-MDIX)"

> So now I'd like to find a document that lists Auto-MDIX status for the
> ethernet chips used with Linux, or to gather the necessary info to put
> such a list together: it's a significant feature, worthy of
> consideration when deciding which NIC/mobo to purchase.

As 1000baseT requires simultaneous transmit and receive on each pair,
the hardware is already there to do it at lower speeds.

I believe the Macs you mention have built in 1000baseT.

I don't know that all 1000baseT NIC will do it at lower speeds, but
I would expect it. I believe the prices are low enough that if there
is any consideration of going to 1000baseT in the future you should
start buying the cards now for new systems.

(Others may, of course, disagree with me.)

-- glen

In comp.os.linux.networking ttsp <(E-Mail Removed)> wrote:

> While googling for info about crossover cables, I found a page which
> says "Most later Macintosh computers are able to use either a
> straight-through Ethernet cable or a crossover Ethernet cable
> automatically through the use of Auto-Medium Dependent Interface
> Crossover (Auto-MDIX)"

This is a transceiver issue, and I think you'll find it depends more on
the card rather than the driver. I could, of course, be wrong however.

I can tell you that the newer Realtek cards do this (or at least the
cheap 10/100/1000 cards I've seen do)

http://www.dse.co.nz/ Product: XH6812

--
Cameron Kerr
(E-Mail Removed) : http://nzgeeks.org/cameron/
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