[Techtalk] Slow networking connection

Raven, corporate courtesan raven at oneeyedcrow.net
Wed Jan 30 19:29:30 EST 2002

Heya --

Quoth Jenn Vesperman (Thu, Jan 31, 2002 at 09:28:27AM +1100):
> > full-duplex, when in fact it was half-duplex.  I (still) don't understand
> > what that means, except that my desktop error log filled up with complaints
> > when it saw the laptop trying to communicate with it.
> Full duplex: like a proper telephone. Both sides can 'speak'
> simultaneously.  Half duplex: like most speakerphones. Only one side
> can speak at a time, the others' data is lost.  For a more technical
> explanation, ask someone else. :) But this will do for most people, I
> would imagine.
	Yah, like Jenn said, full duplex means that you can send and
recieve at the same time.  Half duplex means that you can only do one or
the other at a time.  If you have one side of an Ethernet connection
configured full duplex and the other at half, the full duplex will try
to send when it ought to be listening, and whatever it was trying to
send gets lost.  (The half duplex port will detect the Ethernet
collision, back off, and resend at a random interval.  The full duplex
port won't.)

        I would guess that for ssh, telnet, etc., bandwidth usage
was light, and so there weren't enough collisions to cause problems
with your connection.  But file transfers are larger bandwidth eaters,
and your system couldn't recover from the collisions caused by the
misconfigured driver.

        Words of experience: don't ever trust auto-detect for Ethernet
duplex/speed issues.  Hard-code it if you can, and save yourself many

"I'm not good at running.  But I can yell really loudly.  That works too."
  -- Paul, on pursuit

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