Subject: Re: [RAM] Ramblings about "locator"

From: [email-masked] (Noel Chiappa)
Date: Fri, 15 Jun 2007 08:50:13 -0400 (EDT)

> From: Brian E Carpenter <[email-masked]>

    > My original RAMble (sorry) ended thus:

    >  Maybe the essential point is that a locator can at least in
    >  principle be mapped to topology and an identifier can't.

My human-name can be mapped to a telephone number. My human-name is not,
however, a telephone number. An "identifier" can certainly be mapped to a
network location with the aid of the appropriate database, just as a DNS
name can be mapped to a network location.

Maybe you're using the wrong word, and instead of "mapped" you really meant
something like 'directly related', or something like that, but the problem
is that that's a somewhat nebulous turn of phrase. Which is why I
previously suggested that nice gold-standard, easily-comprehendable tests
for 'does this name have location information embedded in it' are:

- Do you have to get a new one when you move to a new location?
- Given two location-based names, can you tell, by comparing *just the
	names*, whether they are 'close' to each other?

Maybe someone else can come up with a snappy word/phrase which clearly,
cleanly and concisely embodies that very close relationship...

    > A slightly different way to say it is that a locator is a handle for
    > a route.

No. My street address is not a handle (in any simple sense) for directions to
my house. Yes, with a lot of data (connectivity information), and a certain
amount of computing, it can be turned into directions, but the relationship is
not a simple one.

This was all quite clear a long time ago; see IEN-19, John Shoch,
"Inter-Network Naming, Addressing, and Routing", January 1978, now finally
available at:

    ftp://ftp.isi.edu/in-notes/ien/ien19.txt

Everyone here should be familiar with what it has to say.

	Noel

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---

From: Peter Sherbin <[email-masked]>
Date: Fri, 15 Jun 2007 06:58:18 -0700 (PDT)

> - Do you have to get a new one when you move?

IMO that is all you need to tell a loc from an id.

Thanks,
Peter

> Everyone here should be familiar with what it has to say.

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---

From: Brian E Carpenter <[email-masked]>
Date: Mon, 18 Jun 2007 10:12:15 +0200

Noel,

Well, let me quote Schoch:

 >>     At the time one wishes to communicate with a particular address, there
 >>     will be some mechanism that will map an address into an appropriate
 >>     route.
 >>
 >>     The address (where something is) need not be bound to the route (how to
 >>     get there) until this mapping takes place; the choice of an "appropriate"
 >>     route may change over time.

The thing is, Schoch didn't separate the loc and id aspects of addresses
(after all, the whole point was a single logical addressing scheme for the
whole catenet). So this issue we're discussing didn't arise. However, what
he writes seems to me to apply to locators.

> amount of computing, it can be turned into directions, but the relationship is

True, but inside a RIB, a locator is definitely going to be what you use
to find a route.

     Brian

---

From: <[email-masked]>
Date: Mon, 18 Jun 2007 10:45:02 +0100

A locator would be a point on a map - expressed in the same language as
all other points on the map (x,y co-ordinates)?
The map can be read to determine the route ?

Louise

-----Original Message-----
From: Brian E Carpenter [mailto:[email-masked]] 
Sent: 18 June 2007 09:12
To: Noel Chiappa
Cc: [email-masked]
Subject: Re: [RAM] Ramblings about "locator"

Noel,

On 2007-06-15 14:50, Noel Chiappa wrote:
> My human-name can be mapped to a telephone number. My human-name is 
> not, however, a telephone number. An "identifier" can certainly be 
> mapped to a network location with the aid of the appropriate database,

> just as a DNS name can be mapped to a network location.
> 
> Maybe you're using the wrong word, and instead of "mapped" you really 
> meant something like 'directly related', or something like that, but 
> the problem is that that's a somewhat nebulous turn of phrase. Which 
> is why I previously suggested that nice gold-standard, 
> easily-comprehendable tests for 'does this name have location
information embedded in it' are:

The thing is, Schoch didn't separate the loc and id aspects of addresses
(after all, the whole point was a single logical addressing scheme for
the whole catenet). So this issue we're discussing didn't arise.
However, what he writes seems to me to apply to locators.

> Maybe someone else can come up with a snappy word/phrase which 
> clearly, cleanly and concisely embodies that very close
relationship...
> No. My street address is not a handle (in any simple sense) for 
> directions to my house. Yes, with a lot of data (connectivity 
> information), and a certain amount of computing, it can be turned into

> directions, but the relationship is not a simple one.

     Brian
> "Inter-Network Naming, Addressing, and Routing", January 1978, now 
> finally available at:
>