Vernon Schryver wrote:


> But as others have said, the result is unlikely to work.


Well, they do work quite well. Not to mention that this is the preferred
setup for master-slave keep-alive communication for redundant firewalls on
OpenBSD.

> One reason is that modern Ethernet hardware tends to want to chatter in both
> directions before passing packets.


and doesn't break if it can't do so.

> Another problem is that many boxes now sold as "Ethernet hubs" are
> really learning bridges instead of Ethernet repeaters and so do not
> forward all packets to all ports. They must be bridges instead of
> repeaters if they are "10/100" hubs or able to connect 10 MHz hosts to
> 100 MHz hosts. If they are cheap, they lack the knobs and switches to
> configure a port to receive all packets, and so no port will see all
> packets.


Then you have to add some MAC flooding. This is exactly why I prefer some
good old classical that you can put in between the line.

> In many large U.S. companies, contractors do most
> "cable pulling," and jumpers and other impermanent cables are built by
> outsider vendors. It's too expensive to build your own short cables,
> unless you are getting Third World wages.


What do you think these vendors are doing? Right: Ethernet cable is so damn
cheap, it's like a natural resource for them. You just pull of some 100
meters, cut them as required, add the plugs and there you go.