Ah, you would think it would have gotten out and around faster. Having slept on it, it came to me to do the obvious experiments. Geez, if I hadn't such humble gifts that being any kind of scientist is out of the question, it's clear where I'd have fallen between the theoretical physicists and the experimental ones. Why did I not think of this earlier?
Results
Code:
Cable End A Cable End B Carrier?
---------------------------------------------------------------
Net4801 Asus Z35 No
Cable modem Asus Z35 Yes
HP Elitebook 8440 Asus Z35 Yes
Interpretation: the elitebook has the auto switching capability. The cable modem does too or else has reverse connections -- perhaps the latter is more likely. Neither the Soekris Net4801 nor the Asus Z35(fm?) has auto MDI-X.
Thanks for taking the time. I guess I have to go to the store for a crossover cable.