RE: [RAM] Ramblings about "locator"

<louise.burness@bt.com> Mon, 18 June 2007 09:46 UTC

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Subject: RE: [RAM] Ramblings about "locator"
Date: Mon, 18 Jun 2007 10:45:02 +0100
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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:brian.e.carpenter@gmail.com] 
Sent: 18 June 2007 09:12
To: Noel Chiappa
Cc: ram@iab.org
Subject: Re: [RAM] Ramblings about "locator"

Noel,

On 2007-06-15 14:50, Noel Chiappa wrote:
>     > From: Brian E Carpenter <brian.e.carpenter@gmail.com>
> 
>     > 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:

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.

> 
> - 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.

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

     Brian
> 
> 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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