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Uthernet and half-duplex/full-duplex negotiation

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Dear all,

I'm once again improving and testing the Marina IP stack for a June 2016
edition. I've set up two Apple II computers which are connected with a
straight-through Ethernet cable. One is running the original Uthernet, the
other has the new Uthernet II. I notice that the Uthernet II does not enter
into full-duplex mode, and further more, that it seems to receive its own
transmissions. Or at least there is some hang-up which causes Marina to get
stuck in the ARP Address Conflict Detection Probe loop until I pull the
cable and finally it settles into normal operation. This infinite loop does
not seem to happen on the Uthernet machine, but it ends up receiving the
flood of ARP probes.

This problem also does not happen at all when both machines are running an
Uthernet II. Both cards enter into 100 Mb/s, full duplex mode.

I've checked the manufacturer's documentation for both cards and it's not
very clear on how to change from full to half-duplex. Indeed, the W5100
manual includes basically no documentation on full vs half duplex.

Has anyone run into this problem and can provide a solution or something to
check for in my code?

Or maybe I just need to use an actual cross-over cable? I don't think I have
one with me at the moment, otherwise I would have tried it before posting
here.

-- 
]DF$
The Marina IP stack for Apple II--
http://marina.a2hq.com/

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Uthernet and half-duplex/full-duplex negotiation D Finnigan <dog_cow@macgui.com> - 2016-06-11 16:04 +0000
  Re: Uthernet and half-duplex/full-duplex negotiation Tom Greene <tom@cowgod.org> - 2016-06-17 08:24 -0700
    Re: Uthernet and half-duplex/full-duplex negotiation D Finnigan <dog_cow@macgui.com> - 2016-06-17 21:28 +0000

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