tulip driver & Asante Fast 10/100 card

[Dave Platt]

> If you are using half-duplex on either end (ie these combinations:
> half-duplex on both ends, half-duplex on machine and full-duplex on
> switch, or full-duplex on machine and half-duplex on switch), it never
> locks up.  If, however, you are using full-duplex on both ends, it always
> locks up once you try to receive a large file with FTP.  If, again while
> both ends are at full-duplex, I try to _send_ a large file with FTP, I get
> this (also easily reproduceable):

It might be worth going over your cabling with a fine-tooth comb, and
checking for any cable segments which are improperly wired.

I've seen a _lot_ of "Cat-5" cables wired up wrong.  Many cables (both
manufactured in-house, and commercially purchased) simply connect
the four Cat-5 pairs sequentially across the pins of the RJ-45
connector.  This is a violation of proper wiring practice, because
the 10- and 100-Base-T signals are _not_ paired up in this fashion.

I've even seen some facilities wired up wrong - the eight conductors
in the Cat-5 cable were punched down into the 110 blocks in this
straight-across fashion.

If you try to run Ethernet over this sort of cable setup, bad things
can happen.  You'll be sending a signal which _should_ be travelling
along one specific tightly-twisted pair, over two wires which are
actually in two different pairs.  This will mess up the characteristic
impedance of the cable (leading to possible signal reflections),
cause the cable to radiate more EMI than it would otherwise, and
leave the signal more prone to external interference, crosstalk,
and so forth.

I'd expect that full-duplex transmission over a miswired cable would be
particular vulnerable to problems, because both pairs are active
simultaneously.  If you've got any sort of crosstalk problem within
the cable, full-duplex transmission could really exaggerate it.

There are even worse sorts of miswiring possible (and I'm sure that
most of them have occurred in one place or another).  Things would
get really messy if, for example, someone managed to "cross pairs",
so that parts of the TX and RX signals were accidentally being carried
by wires in the same twisted pair.  You'd have unbelievable crosstalk
problems in that case!