Subject: Re: The state of IPv6 multihoming development

From: [email-masked] (Sean Doran)
Date: Fri, 25 Oct 2002 00:44:03 +0000 (GMT)

> The IRTF doesn't agree:
> 
> http://www.ietf.org/internet-drafts/draft-irtf-routing-reqs-groupa-00.txt

Requirements Group A no more represents the formal position
of the IRTF than multi6 represents the formal position
of the IETF.  The former is roughly analogous to a working
group within the Routing Research Group, which is very
roughly analogous to an IETF area.

I am very glad that you are reading the documents, and
the editor is planning an update of this particular
draft, and certainly would appreciate comments on
that (or even on the one whose URL is above),
should you choose to make them.

However, there is a draft here in this wg which could
use some comments too (hint, hint, hint).

	Sean.

---

From: Iljitsch van Beijnum <[email-masked]>
Date: Fri, 25 Oct 2002 09:18:09 +0200 (CEST)

> of the IETF.

Aaarghh, you're not going to let me get away with _any_ hyperbole, are
you?

> should you choose to make them.

I don't know if I could forget about real-world concerns long enough to
make useful suggestions... For instance, in theory I agree with the
point that we shouldn't assume a network topology (so geography is out)
but how much are we willing to pay for not assuming this? In the real
there are interconnection points within 2000 km or so from
well-connected locations for good reasons: it helps robustness, keeps
speed of light delays in check and it's usually cheaper. So why not
optimize for this, at least in the absense of something that is better
in al regards?

PS. Sorry about my last email but I really found that comment to be
insulting, especially as it seems he didn't read the soon-to-be-draft
that explains how it works.

Iljitsch

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From: RJ Atkinson <[email-masked]>
Date: Wed, 30 Oct 2002 03:47:00 -0500

On Friday, Oct 25, 2002, at 03:18 America/Montreal, Iljitsch van 
Beijnum wrote:
> In the real there are interconnection points within 2000 km or so from

That is not universal reality with North American networks at least.
I also have found it not to be the case with some commercial networks
in Europe and Asia/Pacific.

My main objection to so-called "geographic addressing" is that it is 
often
not congruent with the actual network topology.

Ran

---

From: "Tony Hain" <[email-masked]>
Date: Wed, 30 Oct 2002 12:35:53 -0800

> That is not universal reality with North American networks at 

So expand the scope of the statement to 3000 km, and it holds for the
densely populated parts of North America.

> I also have found it not to be the case with some 
> commercial networks in Europe and Asia/Pacific.

We can always find a exception, the question is can we find an approach
that minimizes the number and impact of those exceptions? If we insist
on finding the grand solution that will work for all cases, we will
never do anything.

> not congruent with the actual network topology.

Over an arbitrary scope, you are correct. If we take a large enough
scope, it becomes less clear. After all, there are only so many physical
fiber runs under the oceans, and the places where they terminate is an
even smaller number. Granted the logical circuit topology is not limited
to that, but again, how many real exceptions will exist, and how many of
those will exist despite every attempt to prevent them? 

I content that particularly in the case where someone has gone to the
expense to pull a direct circuit out of their region, they will insist
on and get flat routing in the remote region. The question is can we
abstract that away in other regions? 

Tony

---

From: RJ Atkinson <[email-masked]>
Date: Wed, 30 Oct 2002 16:15:49 -0500

> on finding the grand solution that will work for all cases, we will

I think it is important to understand what the deployed reality is 
today.
That impacts how widely useful some solutions might be, particularly
in the case of so-called "geographic addressing".  I also think it
is important to understand when a given solution will not work with
some/all deployed networks.  Financial realities mean that an IETF
document standardising a solution that requires more interconnection
probably will not lead to firms changing their topologies anytime soon
to meet such a requirement.

> those will exist despite every attempt to prevent them?

A fair number of exceptions exist today.

And as the scope gets larger, the aggregation potential appears to
decline -- a kind of catch-22.

Ran

---

From: Iljitsch van Beijnum <[email-masked]>
Date: Wed, 30 Oct 2002 22:48:39 +0100 (CET)

> to meet such a requirement.

Nobody is proposing a solution that needs more exchanges in order to be
useful. Just to be safe I've included a statement to this effect in the
abstract of draft-van-beijnum-multi6-isp-int-aggr-00.txt. New exchanges
would only be necessary if this solution were to be used much longer
than intended, but as we approach one multihomer in 10 people even flat
routing for a single city such as New York, Tokio or Mexico City will be
problematic.

> > Granted the logical circuit topology is not limited
> > to that, but again, how many real exceptions will exist, and how many
> > of those will exist despite every attempt to prevent them?

> A fair number of exceptions exist today.

But then what's common today may be tomorrow's exception and the other
way around. For instance, someone with ADSL doing BGP routing with IPv6
and a "real" AS number is very rare today, while the number of
organizations connecting to the internet in far apart locations is
something that regularly happens (although I suspect the actual number
isn't all that high). In the future, this will very likely be different.
It could even be argued that existing cases are of no importance to
routing scalability and it's enough to make new cases scalable.

Also note that as of today, NO end-user networks are multihomed in IPv6.

Iljitsch