[ih] History of duplicate address tests

[touch at strayalpha.com]

Hi, Andy,

Using ARP as duplicate address detection has an unintended and possibly dangerous consequence.

If you ARP your own address, you are also broadcasting the IP/Ethernet association of your endpoint as the requesting party. That can flush caches elsewhere and cause traffic to the previous owner of that endpoint to fail - in some cases (and surprisingly) that includes the endpoint that had that address in the first place.

So I don’t think that qualifies as “safe” duplicate address detection and I wouldn’t say that this would be an origin of that concept, as a result.

YMMV.

Joe

—
Dr. Joe Touch, temporal epistemologist
www.strayalpha.com

> On Nov 29, 2022, at 12:43 PM, Andrew G. Malis via Internet-history <internet-history at elists.isoc.org> wrote:
> 
> John,
> 
> ARP (RFC 826) trivially enables duplicate IPv4 address detection on
> Ethernet networks (just ARP for your own address and see if anyone else
> responds), so I guess November 1982 for IP over Ethernet.
> 
> Cheers,
> Andy
> 
> 
> On Tue, Nov 29, 2022 at 3:23 PM John Kristoff via Internet-history <
> internet-history at elists.isoc.org> wrote:
> 
>> 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
>> --
>> Internet-history mailing list
>> Internet-history at elists.isoc.org
>> https://elists.isoc.org/mailman/listinfo/internet-history
>> 
> -- 
> Internet-history mailing list
> Internet-history at elists.isoc.org
> https://elists.isoc.org/mailman/listinfo/internet-history