Post by RS Wood Post by Ivan Shmakov Post by Rich
True, but if one has a crossover in the toolbox, then it will always
work, even if one has encountered one of the older non-autoswitching
ports on some device.
You mean, on /both/ devices? (As otherwise the autoswitching
port on the device that has it will adapt to the other.)
Guess my question is, once you've connected the two machines via
crossover ethernet cable, then what? Each machine thinks the other is
the router and you can use SFTP between them?
When I first met Ethernet, "Ethernet cable" referred to a fat yellow
coaxial cable, limited to about 1500m in length into which devices
tapped using a vampire connector. What we now call Ethernet cables were
in those days called drop cables and were used to connect the controller
to the vampire connector.
When you plug multiple devices into the back of a switch (or router) you
are, logically, connecting to drop cables to a very, very, very short
Ethernet cable the length of the box! Of course, it's not implemented
that way, but that's what's happening logically. Nowadays the majority
of Ethernet installations have no Ethernet cable at all. This is just
as well because modern fast Ethernet would not work using these old
The point of this TL story is that Ethernet is a broadcast protocol.
Logically, the signals propagate over the net can can be read by any
host. Hosts find each other by replying to broadcast requests of the
form "who is 192.168.1.100?". The reply tells the asker (and anyone
else cares to listen) what the MAC address of host 192.168.1.100 is.
All a cross-over cable did was to simulate a zero-length Ethernet cable,
so provided the two hosts were given different IP addresses everything
from there up would just work.
Post by RS Wood
In response to the comment about SAMBA, NFS, etc.: yes, I use that
stuff regularly. But they require two networked computers and a
router between them to assign addresses. The cool thing about Apple's
Target Firewire mode is that one machine just appeared to the other as
though it were an external drive. Really, shockingly easy to move
files back and forth that way. (I used Chronosync, a GUIfied rsync
with lots of features).
Like USB, Firewire had protocols designed all the way up to the file
server level which is why it all "just worked". You could do that with
Ethernet too, but it would be undesirable -- you don't want everyone's
drive showing up on everyone else's machine because the Ethernet people
stipulated a file sharing protocol that kicks in automatically.