[ih] Why did location/identity separation not happen?

[John Shoch]

I think this sub-thread began with a questions posed by Ole Troan:

"Back to history. IPv6 should have had identifier/locator split from
the start. I wasn’t there, but I understood it was close with Mike
O’Dell’s 8+8 and GSE proposals? Anyone who can shed more light on what
happened and why that path was not chosen?"

Can I presume the syllogism is location:identity :: address:name ?  I can
add a little context, and some historical pointers.

Noel and Jack, thanks for the kind reminder about the paper from 48 years
ago :), when there was an earlier opportunity to address this challenge --
at the time of IPv4.  Those were fun times.

I had discussed the naming/addressing/routing issues at an early Internet
Working Group ca. 1978, trying to suggest what we had done in Pup to define
and de-couple these ideas.  More importantly we were trying to suggest some
of the short-comings of hierarchical addressing,and the direction we were
already going -- in what was to become the second-generation XNS.

I must confess that I don't know exactly what interactions took place over
the next couple of years, but I can only assume that there were a lot of
continuing side conversations about our approach.

About three years later, in Jan. 1981, there was another Internet meeting
at ISI;  the 3 of us were there, as well as a who's-who of internet people
at the time.  The minutes were written by Jon Postel:
    https://www.rfc-editor.org/ien/ien175.txt

One of the items on the agenda was again:
"X.  ADDRESSING DISCUSSION
      Vint Cerf opened the topic with a call for a very general
      discussion of the issues and spent some time developing a list of
      goals for the the addressing and routing procedures."

As was often the case, Vint had his eye on the right target:
"C.  Discussion:
      Vint Cerf led a further discussion on addressing.  The main focus
      was on the tradeoff between a flat address space and a
      hierarchical one.  In a flat address system there is no relation
      between the address and the location, and routing has to be by
      central knowledge or broadcast.  In a hierarchical address system
      the address is composed of fields which identify the location in a
      routing tree.

      Vint suggests that we have both in one!  Let an address be
      composed of two parts: a hierarchical address (called an address)
      and a flat address (called an identifier).  The address can be
      used as a routing guide or hint, but the identifier must match for
      a message to be delivered.  The identifiers are globally unique
      names for hosts and do not change when hosts move."

This was, of course, what had already been implemented in XNS by Yogen
Dalal and the SDD team:
--Every Ethernet interface had a unique 48-bit identifier (MAC address)
drawn from a flat space, with no hierarchy.  (We might call this an
"address" or a "name" -- yes, I know it is hard to map this onto my own
original formulation.)
--This same address was used as the internet address (eliminating any
mapping or ARP between internet addresses and Ethernet addresses!).
--Internet packets, though, also carried a network number -- essentially a
hint as to the network where this address was last seen.
--Gateways would simply use these network numbers for efficient routing of
packets, and did not need to look at the longer unique address (which was
only checked at the destination).
--But if the device had moved (i.e., if the identity had a new location)
the sender would have to fall back to a higher-level lookup (think Xerox
Clearinghouse or DNS) to get a more recent network hint.

So, Vint and a whole room of wizards were discussing location/identity or
address/name 45 years ago.

Ole Troan asked, "why that path was not chosen?"

It's a little trite, but we had already taken the advice of Robert Frost:
*"Two roads diverged in a wood, and I—"*
*"I took the one less traveled by,"*
*"And that has made all the difference."*

1981 was about the time I was moving to the business side of things;  maybe
some of you who were there can reconstruct how the other path was chosen,
and became more traveled.....

John Shoch

On Mon, May 18, 2026 at 12:00 PM <internet-history-request at elists.isoc.org>
wrote:

>
> Message: 1
> Date: Mon, 18 May 2026 12:14:47 -0400 (EDT)
> From: jnc at mercury.lcs.mit.edu (Noel Chiappa)
> To: internet-history at elists.isoc.org
> Cc: jnc at mercury.lcs.mit.edu
> Subject: Re: [ih] Why did location/identity separation not happen?
>         (Was: Internet without entrenched factions?)
> Message-ID: <20260518161447.2A23118C073 at mercury.lcs.mit.edu>
>
>     > From: Jack Haverty
>
>     > The issues of location and identity that I first remember seeing were
>     > in John Schoch's IEN in 1978
>
> Jerry builds very heavily, and explicitly, on Shoch's work, in RFC-1498. T
>