Subject: RE: Enforcing unreachability of site local addresses

From: Dan Lanciani <[email-masked]>
Date: Fri, 14 Feb 2003 00:03:47 -0500 (EST)

"Alan E. Beard" <[email-masked]> wrote:

|Yes, I think you are probably right in speculating that any technically
|sound mechanism which preserves the virtues of provider independence,
|portability, and stability in configuration of end-user-network devices
|will satisfy the functional requirements of the end-user community.  It
|seems to be up to us to architect the mechanism(s).

Any thoughts on how we might jump start some activity in this area?  Over
the years I've tried the bottom-up approach by suggesting some possible
mechanisms, and I've tried the top-down approach by suggesting that we try
to reach consensus on how much overhead we are willing to accept in return
for the solution.  The former generally provokes protests that the solution
is too complicated to sketch and the latter usually results in silence.  How
can we get some serious discussion going?

If we do stick our heads in the sand (again) and pretend that provider-based
hierarchical address allocation is temporary (again) then history will likely
repeat itself.  There will be a little v6 swamp to accommodate some edu sites
and those enterprises that are big enough to demand real multi-homed support,
but the rest of us will be stuck with the same kind of unstable/non-portable
addresses we have today in the post-aggregation v4 world.  IMHO, any solution
that attacks the problem by slightly shifting the demarkation point so that
"enough" large enterprises can have PI space to make v6 appear commercially
viable is a sham.  We cannot afford to defer support of the small- and home-
office environment forever.

				Dan Lanciani
				ddl@danlan.*com
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---

From: "Alan E. Beard" <[email-masked]>
Date: Fri, 14 Feb 2003 13:37:42 -0500 (EST)

Dan, Margaret, et al:

I have given some thought to the matters raised below.  This note will
address the questions raised by Dan in his first paragraph; the second
paragraph will see a later response.  Please be aware that the below
should be considered, at its most ambitious, not more than a starting
point for group discussion;  it is not to be considered a formal proposal.

AEB

> can we get some serious discussion going?
[...]
> 				ddl@danlan.*com
It seems to me that we have in recent weeks seen a shouting-match form of
the top-down, how-much-penalty-are-we-willing-to-pay discussion, with one
camp asserting loudly that the PA-with-aggregation scheme is strictly
necessary for the operation of IPv6, and another group insisting
vigorously that any address allocation scheme other than unrestricted PI
will be inevitably and utterly fatal to the continued deployment of IPv6.
This is roughly equivalent to: do we smother the baby now, or poison it
when it reaches puberty?  During this debate, most people with any
reasonable sense of self-preservation (which immmediately excludes me)
were cowering in gator holes, preferring the possibility of a
confrontation with an enraged she-gator to the near certainty of an
encounter with all the lead flying around out in the sawgrass.  In both
cases, the magnitude of the postulated adverse effect was deemed to be
well beyond the pale, and the discussion subsided to a series of
exasperated splutters.

There are a number of paths we might explore to encourage some productive
discusions.  I will suggest below the outline of a sequence which seems to
me attractive.

First, we may wish to start a top-down discussion with the objective of
assembling a list of functional objectives for the address allocation
schemes which have been under discussion here.  Please note that we have a
possible charter problem here - more on that below.

Once we have got rough concensus on the functional objectives, we can
proceed to a bottom-up approach on mechanisms, and from there to specific
proposals for standards, or BCP, or guidance to the registries.

Now, we have a scope problem here, which is a result of the wording of the
WG charter, and is further complicated by the instructions which came of
out the Atlanta meeting.  We probably need to consult Margaret before she
concludes that we have taken the bit in our teeth (which we have) and are
about to put at risk every horse and all the coaches in the staging yard
(still undecided).

At IETF 55 (Atlanta), floor discussions in the WG meeting indicated that a
proposal to limit use of site-local address allocations was contingent, at
least in the minds of many of the attendees, on making provision for some
form of PI address space which is available to most (preferably _all_)
networks. As this last issue did not fall within scope of any of the WG's
defined work items, a decision was taken (how's that for passive voice?)
to refer the matter to another area (SubIP or OAM, if my memory serves
correctly) for consideration. What started in this WG as a discussion
peripheral to the issue of restricting use of SL has now devolved into a
reconsideration of the fundamental principles and assumptions underlying
the address allocation practices for IPv6. This latter discussion is
clearly beyond the scope of the current work items for this working group.
However, the fundamental issues seem unwilling to fold their tents and
steal away quietly into the night.  As I read the WG charter, these
matters are incontestably within the bounds of the charter, although not
subsumed by any extant work item.

IMHO, our discussions so far have identified a matter within the scope of
the charter which urgently requires a resolution and requires further
work toward that end. So far, we have, by dint of quite extraordinary
self-restraint (yeah, right), avoided rogue status by confining our
activities to disussion of the nature and scope of the perceived problems,
rather than commencing formal work upon definition and solution of the
problems.  However, absent explicit assent from the ADs, formal work of
sort suggested above would leave Margaret fully justified in coming 'round
with her elephant gun, placing the muzzle squarely between our ears, and
discharging as many rounds as she sees fit.  (Margaret, I know that you
don't carry an elephant gun: the above description is entirely
metaphorical, and no imputation of violence attaches to you.)

Unlike many judicial bodies, the IETF does not have a compelling tradition
of stare decisis: we are not prohibited from revising previous
recommendations when changed conditions or new information indicate that
the recommendations may no longer comport with reality as we know it.  I
would suggest that the continuing discussions and controversy over the
issue of PI vs PA strongly indicate that additional consideration of IPv6
address allocation practice is urgently needed, if for no other reason
than to assure the IETF and the user community that we are recommending
technically and operationally feasible models for address allocations. (I
will further suggest that the current practices leave that conclusion
somewhat in doubt.)  It seems to me not unreasonable to ask of Margaret,
Rob, Thomas and Erik permission to augment our list of work items with a
specific task to review current guidance to the address registries
concerning address allocation philosophy and procedure with a view to
encouraging user acceptance of IPv6 while maintaining technically sound
policies concerning routing overhead. (Yes, that language is ambiguous and
imprecise to the point of being downright sloppy - we will need better
wording if this is to proceed.)

The multi6 WG has a some papers extant which are related to the address
allocation practices, one of which is Michel Py's gapi-00 draft.
However, there does not seem to be in progress anywhere a comprehensive
reconsideration of address allocation practices as related to PA, PI, and
routing table burden, nor any current process which explicitly considers
end-user expectations concerning IPv6 address allocations and uses
permitted thereof.

There are, in my view, two extant items in the IPv6 WG charter which
subsume the work outlined above, to wit:

- Provide technical input to the IAB, IANA and Internet Address Registries
with regard to IPv6 address allocation policies and procedures.

This covers the full discussion and the specific work outlined above.

and

- Serve as a review board and body of competence and coordination for IPv6
architectural issues that span multiple IETF working groups.

The specific issues regarding PA, PI, and aggregation will likely afflict
IDR and OSPF; further, Multi6 has open work on related issues.

In summary, I think that we may have sufficient justification to ask the
WG chairs and the ADs to add a specific task to the list of open WG work
items: that being a review of current address allocation philosophy and
procedures in light of current state of routing protocol specifications
and in light of end-user expectations concerning allocation and permitted
use of IPv6 addressing.

What think ye all?

AEB

-- 
Alan E. Beard <[email-masked]>
AEBeard Consulting; 4109 Chelsa Ln; Lakeland FL 33809
863.815.2529

---

From: "Tony Hain" <[email-masked]>
Date: Fri, 14 Feb 2003 11:51:52 -0800

Alan E. Beard wrote:
> ...

We are at an impass. The right outcome is that multi6 defines an
approach that works for end sites, while scaling appropriately for the
ISP concerns. The reality is that multi6 is off in the weeds
rearchitecting the Internet, with no more hope of a useful outcome than
the IRTF routing research wg has produced over the last N years.
Unfortunately, this puts the ADs in a bind, because they would have a
hard time justifing that the IPv6 wg should be tasked with defining an
operational plan that an Operations Area wg is already tasked to do. 

It could be argued that since we are talking about allocations which
conform to addr-arch-v3, the IETF is not the right place for the
discussion anyway. The sticking point is that if we are talking about
space other than 0x001, IANA would need to allocate that, which they are
reluctant to do so without IESG buy-in, and since the IESG is in a bind,
nothing can happen.

Another data point for the discussion. At the NANOG earlier this week,
Daniel Golding presented a discussion
(http://www.nanog.org/mtg-0302/golding.html) about evolving the
peering/inter-provider relationships along the lines where regional
exchanges might reasonably become brokers between the regional ISPs &
the transit providers. It is exactly that business model where PI
approaches like Michele's or mine work well. 

Right now the IETF is stuck working on the assumption that we have to
have a single global DFZ that knows all TE exception cases (even outside
the scope of where they make sense), and that both the ISP & the end
customers get to have full control of all the knobs. One could argue
that it is the IETFs role to define the knobs, get out of the way, then
watch and take the lessons learned as input for revising the function of
said knobs. While it is frequently attempted, it is rarely wise to
legislate operational behavior through the standards process. 

Despite all that, several people have continued to persue personal
drafts with the expectation that eventually an appropriate forum will be
found. 
Michele maintains a site with the active efforts at:
http://arneill-py.sacramento.ca.us/ipv6mh/ 

I have a document that describes the situation and need for PI:
http://www.tndh.net/~tony/ietf/ipv6piaddressusage-04.txt
and a companion doc which describes one approach to a PI allocation
scheme:
http://www.tndh.net/~tony/ietf/ipv6piaddressformat-04.txt
both of which I plan to refresh before the cutoff. Comments are welcome.

Tony