This is really fascinating.  At the physical level, there's noting that
would tell either device that the cable in use is a crossover.

  There *is* a whole range of weird problems which can arise because
different manufacturers differently interpret the Ethernet specification for
automatic negotiation of full/half duplex.
  If that were the case, though, I'd expect the significant factor to be the
brand/model of NIC, rather than the OS version.  It's just possible that
there's a common NIC driver issue associated with the reporting of
connection properties back to Windows (previous versions generally didn't
have a way to show the connection status and speed), but I'd expect a
problem at that level to carry over to XP.

  I'm curious about this Digibox device, too.  The only "port server"
devices I've ever used connected a set of serial ports (to which modems were
usually attached) to a single Ethernet port.  Is that what this is?

David Gillett


On 11 Dec 2003 at 12:00, JMB wrote:

> Maybe this info will help - maybe it won't - but have a read. We were
> installing our software on a customer's W2K computers and using a
> reversed (null-modem type) Cat-5 cable (not a straight-thru) to connect
> it to a Digibox port server. We could never 'see' the port server from
> the computer. Hooking up our own portables with W2K didn't help. After a
> frustrating day of trying to track down the problem, I called Digibox (a
> very reputable company). After sever techs tried to help, I was talking
> with a chief tech who then asked what OS was the computer using? When I
> said W2K, her immediate reply was hook up the computer to the port
> server using a hub/switch and straight cables, not null-modem cables.
> Seems there is a little bug with W2K that if it senses a problem of any
> kind when it has a null-modem cable connected to its NIC connection, it
> automatically drops off the interconnect and disables the NIC with no
> warning (usually the NIC icon in the system tray disappears). According
> to her, this little fact has caused untold problems. So after buying
> some cheap switches and straight Cat-5 cables, all of their computers
> worked without further problems.
>
> Jean Bourvic

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