Date:        Wed, 17 Dec 2003 14:22:08 +0900
    From:        henry nelson <netb@irm.nara.kindai.ac.jp>
    Message-ID:  <20031217052208.GA28790@irm.nara.kindai.ac.jp>

  | Adding interface aliases:
  | ep0: DAD detected duplicate IPv6 address fe80:0001::0260:97ff:fe13:39e7: 20 NS, 0 NA
  | ep0: DAD complete for fe80:0001::0260:97ff:fe13:39e7 - duplicate found
  | ep0: manual intervention required
  | 
  | I have absolutely no idea what "DAD" is or where to begin to research
  | this problem.  What kind of "manual intervention [is] required"?  Should
  | I just turn IPv6 off (How?) since I'm not using it?

DAD is Duplicate Address Detection

You're being told that two different systems have the same IPv6 address
on the LAN - this is not good at all.

Since that address is usually automatically generated from the MAC address,
unless some other system has been manually set up to defeat you, it is
likely to mean duplicate MAC addresses.

The manual intervention is to trash the card that has a duplicate address.

Or, it may be that something on the LAN is deliberately faking duplicate
addresses, in which case the intervention is to find whoever installed that,
and have them drawn and quartered - or if the culprit can't be located, at
least remove the offending equipment.

It is also possible this can happen if you are using a Sun (or other system
that uses the same MAC address on multiple interfaces) and you have more
than one interface connected to the same LAN - the intervention required
there is to manually assign a different Link Local address to one (or really,
all but one) of the affected interfaces.   (But given "ep0" that's not likely).

kre