[ih] History of duplicate address tests

[John Kristoff]

My earliest memory, because that is the time of my entry into the
field, of duplicate address detection was done on Token Ring networks
during ring insertion (phase 2 - address verification).  More recently
IPv6 has duplicate address detection (dad).

I'm curious to know about the earliest of duplicate address detection
mechanisms.  I imagine there were some predating what I remember about
Token Ring, but this is the kind of thing that is difficult to uncover
without some hints. Any pointers to the earliest of these functions in
networking?

Thanks kindly,

John