Re: Why did location/identity separation not happen? (Was: Internet without entrenched factions?)

> On May 20, 2026, at 5:10 PM, vinton cerf via Internet-history <[email protected]> wrote:
> 
>> End-point has always been an intuitively appealing, but IMO problematic,
>> term.  Is it an interface?  A host?  An application? (And which layer of
>> an application service?  I always thought of an email address as
>> defining an endpoint.  Until I dealt with EDI over email, where the
>> receiving email inbox was only an intermediary, and an EDI identifier
>> indicated that ultimate end-point..)
>> 
> well, could one argue the endpoint at the IP layer gets you to the host,
> TCP gets you to a process and after that it is an application layer
> question?

In Ethernet, address=interface, i.e., the “strong host” model. If a (unicast) frame doesn’t arrive at the correct interface, it’s dropped.

For IP, address=host, even though there’s one or more IP addresses per interface, i.e., the “weak host” model. IP source addresses match interfaces when they go out, but “any port in a storm” is valid on input.

This is discussed in RFC1122.

FWIW, from my seat, the discussion location vs. identity hasn’t mentioned what I think are some key points:

	1) location vs. identity is one of label structure. Unstructured labels are considered names. 
	Structured labels, where structure matches topology or place, are considered locations.
	They’re all just labels - it’s the structure and its meaning that make the difference.

	2) having multiple addresses, whether in a single header or stacked headers, is just a variation on indirection.
	One label provides the context (environment) and another provides the indicator within that environment (item).

IMO, no single structure or environment/item pair ever satisfies everyone.

Joe
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