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Re: Some Comments on ID/Loc Separation Proposals

On 28-nov-03, at 0:39, Dave Crocker wrote:

My primary interest is in having precise definitions that we all find
useful and use consistently. Some of the current versions of
definitions in the draft are:

Endpoint 

           refers to "the fundamental entity of and end-end
           communication" [EID]. It is an end-system that participates
           in an association. Endpoints are distinguished from
           intermediate, infrastructure nodes and from hosts.

An endpoint is an end-system but not a host: I think this isn't all that clear.

Personally, I prefer to talk about hosts, as this is a well-known concept. The fact that there is some ambiguity because hosts can be clustered and virtualized also isn't a huge surprise to most people, and can be spelled out for good measure.

If you want to stick to "endpoints" you should say whether an endpoint is host that may or may not be virtual, a transport protocol or a process. This has pretty serious consequences for the number of identifiers that is necessary and some other stuff as well. For instance, certain types of communication may be handled by more than a single processes. When identifiers are tied to processes this makes referral very complex.

Identifier

refers to a unique label for an endpoint.

Hm, maybe this is just my English but to me it is unclear whether you mean the identifier <-> endpoint relationship is 1-to-1, 1-to-n or n-to-1, only that it isn't n-to-m.

I think "an identifier identifies a specific endpoint" is enough.

           The label is used
           simply for distinguishing one endpoint from another.
           Because a locator is usually globally unique, it might be
           able to serve as an identifier. However this use will often
           suffer administrative and referential limitations as a
           global identifier for mobile endpoints. This is exemplified
           by the current problems experienced with the dual role of
           IP Addresses.

This is too much text and largely not relevant for defining "identifier". The only additional remark that's necessary is that an identifier is independent of an endpoint's attachment to the network ("location").

As with others, I do not think it is useful to have ID refer to an
interface.  Stack, endpoint or process all seem more helpful.

Absolutely. While multi6 is about site multihoming and not host multihoming, it would be a mistake only allow jumping locators when those locators are tied to the same interface.

"Endpoint" is usable, but "stack" isn't a very good word as it will probably confuse people who haven't followed what has happened in the NSRG and identifying processes is too granular and dynamic, IMO.