SUN-3 messages - ie0: no carrier

[Ron Hitchens, Sun Wiz]

> We are experiencing frequent error messages on our SUN-3 consoles
> saying "ie0: no carrier".  This happens infrequently on our SUN-2s
> as well, but not nearly as often.  It happens on both file servers
> and clients.  Our SUNs are attached to the ethernet using DELNIs.
> Can anyone shed light on this problem?

   We've seen this on all of our Sun3s also, and similar messages on
our Sun2s (usually iebark reset).  My guess is that these are being
caused by net collisions.  When the ethernet is in a jammed state
there is effectively no carrier on the wire.  The specs specify a time
frame in which the sender is supposed to detect collision and stop
transmitting.  On a network of any size at all it's quite common to
have "massive collisions", caused by any number of factors, which
can keep the net jammed for far longer than the specified time.  It's
my guess that the Sun board is noticing that carrier has been absent
for too long and causing the "no carrier" message.

   This would also explain why the message is not "ethernet jammed".
I believe the "jammed" message (which you'll get if the coax is 
unterminated) is caused when the signal in the coax goes out of spec.
The collision state is a specific signal on the cable.

   This is my guess, I haven't done any investigation to verify it.
I have observed getting flurries of these message at times when we
know there are "rogue" machines on the net doing strange things.

   So long as you're only getting one or two a day, I'd say not to
worry about it.  It's unlikely to be a hardware or cable problem, since
it happens on most Sun3s.

Ron Hitchens		hitchens at godzilla.cs.utexas.edu
			...!ut-sally!hitchens