Subject: RE: The state of IPv6 multihoming development

From: "J. Noel Chiappa" <[email-masked]>
Date: Thu, 24 Oct 2002 12:20:47 -0400

> From: "Tony Hain" <[email-masked]>

    >> naming them "provider-dependent" and "provider-independent"
    >> addresses, thereby completely obscuring the underlying technical
    >> issues, and making it seem like it's purely a policy issue .. If
    >> you want technically accurate terminology .. call them
    >> "connectivity-dependent" and "connectivity-independent".

    > There was no attempt to make this a political argument, in fact it
    > is more accurate than connectivity-*. The current policy says
    > customers get their prefix from their provider so that it
    > aggregates, therefore it is provider-dependent. End sites are
    > looking for a mechanism that allows them to decouple their prefix
    > from any specific provider, therefore it is provider-independent.

Look, there are network designs which allow connectivity-dependent
addressing schemes which are *not* provider-dependent.

E.g. if a (large enough) bunch of customers band together and create an
exchange, which buys service from multiple ISP's, and which is given an
address which is visible over the same scope as those ISP's, and the
customers are addressed as part of that exchange, you meet the policy goal
(being able to change providers) *without* so-called "PI" addresses. But the
addresses are still connectivity-based.

So there's one really good reason to discard this bogus "provider-dependent"
and "provider-independent" terminology - because there are cases in which it
*doesn't* align with the underlying technical issue.

Perhaps if people understood the underlying technical issues better this
discussion would be more fruitful. Using terminology which *accurately*
conveys the underlying fundamental technical limitations, rather than their
policy goals, is a good place to start.

	Noel

---

From: "Tony Hain" <[email-masked]>
Date: Thu, 24 Oct 2002 10:53:12 -0700

J. Noel Chiappa wrote:
> ...
> Look, there are network designs which allow 
> connectivity-dependent addressing schemes which are *not* 
> provider-dependent.
> 
> E.g. if a (large enough) bunch of customers band together and 
> create an exchange, which buys service from multiple ISP's, 
> and which is given an address which is visible over the same 
> scope as those ISP's, and the customers are addressed as part 
> of that exchange, you meet the policy goal (being able to 
> change providers) *without* so-called "PI" addresses. But the 

So we are arguing the same point, so this is simple semantics. I was
simply using a global algorithmic mapping to allocate the prefix for the
exchange.
 
> So there's one really good reason to discard this bogus 
> "provider-dependent" and "provider-independent" terminology - 
> because there are cases in which it

Fine, we need to come up with a paragraph that clearly gets the point
across.

> 
> Perhaps if people understood the underlying technical issues 
> better this discussion would be more fruitful. Using 
> terminology which *accurately* conveys the underlying 
> fundamental technical limitations, rather than their policy 
> goals, is a good place to start.

Both apply, so we just need to be very clear.

Tony

---

From: Iljitsch van Beijnum <[email-masked]>
Date: Thu, 24 Oct 2002 20:27:56 +0200 (CEST)

> addresses are still connectivity-based.

Semantics. The exchange would be the "provider" here.

BTW, this looks an awful lot like geographical addressing and
aggregating. Now if we virtualize the exchange that saves a lot of iron.

---

From: Brian E Carpenter <[email-masked]>
Date: Fri, 25 Oct 2002 16:38:45 +0200

> Semantics. The exchange would be the "provider" here.

The problem with this (and the reason I have serious doubts about
Tony's PI proposal, and all geographical proposals going back at
least to Bill Simpson's metro proposal years ago), is

  There is no economic reason to create such an exchange.

If we could get past that, of course it works. And there isn't much
the IETF can do about it. We could perfectly well make the case to get
the PI block from IANA, but that doesn't get it deployed. As Noel notes,
you don't even need PI space to create an exchange-based addressing
scheme. You don't even need PA space - you could build a metro exchange
using 6to4 space if you were desparate.

> aggregating. 

Of course.

> Now if we virtualize the exchange that saves a lot of iron.

Pls explain.

  Brian

---

From: Iljitsch van Beijnum <[email-masked]>
Date: Mon, 28 Oct 2002 19:56:29 +0100 (CET)

You asked why not roll out SCTP? I seem to remember more problems with
SCTP than just the obvious ones, but those are:

* not every application uses a TCP-like transport mechanism
* no backward compatibility
* multiple addresses per host is a management nightmare in large networks

> Pls explain.

If you have an exchange in region X, you can have some kind of
exchange-based adressing. So now remove the exchange and keep the
addresses. Now you need to find the shortest path between each
combination of networks to exchange traffic towards destinations in
region X. There are potentially at least, many ways to do this:

* tunnels
* layer 2 "tunnels" using stuff like ATM or MPLS
* more specific routes
* separate routers for region X in region Y