Subject: Re: [rrg] Consensus check: terminology

From: [email-masked] (Noel Chiappa)
Date: Wed, 8 Apr 2009 12:15:42 -0400 (EDT)

> From: William Herrin <[email-masked]>

    > these definitions don't provide me with a useful language to talk about
    > routing.

I agree - but the solution is not to warp these terms into meanings useful to
routing; rather, define some _more_ terms which are useful for that.

    > In addition, the definition of address is demonstrably wrong.
    > ...
    > Counterexample #2: The IP address of an anycasted DNS service.

True. So change the definition to be "a name that is usually used", and in
the expanded text, mention that multicast, anycast, etc don't fit within that
last part of that definition.

There is simply no way to produce a definition which both i) completely and
accurately describes all the uses to which an IPvN address is currently put,
and ii) is short and crisp.

	Noel

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From: Tony Li <[email-masked]>
Date: Wed, 08 Apr 2009 21:24:58 -0700

> and ii) is short and crisp.

So true.  And it would seem that i) is a clear indication of the amount 
of overloading that we've applied to the IPv4 namespace.

Tony

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From: Dino Farinacci <[email-masked]>
Date: Wed, 8 Apr 2009 21:47:01 -0700

> So true.  And it would seem that i) is a clear indication of the  
> amount of overloading that we've applied to the IPv4 namespace.

Is a group address a locator or ID?

For LISP, it is considered an EID since it doesn't map to topology and  
when a host moves around and stays joined to the group, the group  
address doesn't change. So it is close to your definition of  
"Identifier".

Dino

>
>
> Tony
>
>
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> [email-masked]
> http://www.irtf.org/mailman/listinfo/rrg

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From: Dino Farinacci <[email-masked]>
Date: Wed, 8 Apr 2009 21:48:04 -0700

> For LISP, it is considered an EID since it doesn't map to topology  
> and when a host moves around and stays joined to the group, the  
> group address doesn't change. So it is close to your definition of  
> "Identifier".

I have a typo above. Please s/EID/ID.

Dino

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From: Tony Li <[email-masked]>
Date: Wed, 08 Apr 2009 22:06:37 -0700

> I have a typo above. Please s/EID/ID.

I'd concur with identifier.  Is there some issue with that?

Tony

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From: Dino Farinacci <[email-masked]>
Date: Wed, 8 Apr 2009 22:09:52 -0700

> I'd concur with identifier.  Is there some issue with that?

Just wondering if you should include a group address in your  
definition. Up until now, I think everyone is thinking about unicast- 
type addresses.

And also, to bring up the point Joel made, an anycast address is also  
known as a way to use (or abuse) a unicast address. Rather than having  
a formal definition and encoding (like IPv6 does).

Dino

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From: Tony Li <[email-masked]>
Date: Wed, 08 Apr 2009 22:19:25 -0700

> Just wondering if you should include a group address in your definition. 
> Up until now, I think everyone is thinking about unicast-type addresses.

Not necessary, I think, as our charter is to define these terms for 
abstract discussions, not document current (ab)uses.

I think we're in agreement that 'group address' is actually only a 
result of the overloading of 'group identifiers' onto a true 'address 
space'.

> known as a way to use (or abuse) a unicast address. Rather than having a 
> formal definition and encoding (like IPv6 does).

Agreed.  Just another overloading...

Tony

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From: Scott Brim <[email-masked]>
Date: Thu, 09 Apr 2009 16:55:09 -0400

Dino Farinacci allegedly wrote on 04 09 2009 12:47 AM:
> address doesn't change. So it is close to your definition of "Identifier".
> 
> Dino

Are you talking about multicast group addresses?  They are a perfect
example of a forwarding selector.  At each hop, forwarding uses them to
decide on a next-hop, but they do not name a particular point of attachment.

Just because they are not 'locators' doesn't mean they are identifiers.

What was it Noel said about trying to fit everything into too few names?