Subject: Re: Deployment vs the IPv6 community's ambivalence towards large providers

From: Vernon Schryver <[email-masked]>
Date: Tue, 22 Aug 2000 09:25:52 -0600 (MDT)

> From: Robert Elz <[email-masked]>

>   | Both IPv6 and ATM-to-the-desktop-and-replacing-IP
>   |    - require major changes to applications, hosts TCP code, and the boxes
>   |        that connect hosts.
>
> The IPv6 changes range between fairly minor and non-existant, depending upon
> the application (and when done, result in code that still works over IPv4).

To the extent that is true, it could also have been true of ATM.  You
could have had yet another address family, gethostbyname2(), and
N-to-A/A-to-N for ATM that would have been just as hard or difficult for
applications as as the IPv6 solution.  I suspect whether the application
changes for IPv6 are major or minor depends mostly on whether you're making
them, and whether you have source so that you can make them.  If your
application never directly handles addresses, and you have inet_pton()
that works (the widely distributed code is, well, imperfect even for IPv4),
then the changes are not too painful.  If your application or worse your
protocol need to deal directly with addresses, then things get sticky.
128 bits pegs don't fit in 32 bit holes, at least not on the systems and
networks I fight.

>   |    - claim to be desert toppings AND floor waxes
>
> No, IPv6 claims only to be a (really fairly minor) enhancement of IPv4

Have you seen the SNL skit?

Whether IPv6 is a really fairly minor enhancement of IPv4 is as true of
ATM to the desktop.  The ATM mavens claimed that jacking up desktops and
replacing IP with ATM would have been trivial.  On the other hand, some
IPv6 advocates never stop beating the drums for IPv6 QoS, multi-homing,
and so forth and how the Millennium will arrive with IPv6.  I think
the truth in both cases is not so simple as either minor enhancment
or dawning of a new age.

> ATM requires new hardware (everywhere), IPv6 runs just fine on ancient
> hardware (my main stable IPv6 node is a 486 from about a decade ago...

Yes, that's a very good point.  Dealing with cells at reasonable speed
couldn't be done with software, although modern routers aren't doing
badly with 48 byte TCP-LW/IP datagrams.

> The two aren't comparable at all in terms of what they're attempting to do,
> or what is involved in upgrading from one to another.

You have a point in the hardware hassles, but not about the other half.
ATM was driven mostly by telephant hopes and fears, but it also claimed
some of the IPv6 wonders.  IPv6 is only rationally justified as a modest
but necessary enhancement to IPv4, but never say that or worse, mention
obvious implications of that fact in the hearing of an IPv6 adovocate or
you'll feel as if it were 1985 and you'd mentioned TCP/IP within earshot
of real (i.e. ISO OSI) network expert.  Sean has been provactive, but some
of the reactions have been comically similar to what I heard from
participants in the then dominant standards committee not that many years
ago.  In other words, the IETF has come of age.

Vernon Schryver    [email-masked]

---

From: Thomas Narten <[email-masked]>
Date: Wed, 23 Aug 2000 07:15:33 -0400

> On the other hand, some IPv6 advocates never stop beating the drums
> for IPv6 QoS, multi-homing, and so forth and how the Millennium will
> arrive with IPv6.  I think the truth in both cases is not so simple
> as either minor enhancment or dawning of a new age.

It is certainly regretful that there are some that go around touting
IPv6 as the solution to all problems. But if you listen carefully to
what many in the IPv6 community are saying, they are saying that IPv6
provides more addresses, and that that is *the* *main* *benefit*. The
other changes/benefits (simplified autoconfiguration, improved
mobility, tools to help with renumbering, etc.) while important, are
secondary.

> IPv6 is only rationally justified as a modest but necessary
> enhancement to IPv4,

I agree with this, and suspect that much of the core IPv6 community
does as well.

Thomas

---

From: "Rahul Banerjee" <[email-masked]>
Date: Wed, 23 Aug 2000 19:03:05 +1000

Well, not really just the enlarged address space! There do exist certain
other definite benefits of IPv6 like possible use of Flow Specifications in
the Flow Label, decreased processing delay at routers, greater flexibility
etc.  This is not to say that the IPv6 is answer to all problems, but just
to signify the worth of the effort of those working on it.

-Rahul

---

From: Thomas Narten <[email-masked]>
Date: Wed, 23 Aug 2000 10:22:02 -0400

> Well, not really just the enlarged address space!

The enlarged address space is the *primary* benefit. While there are
certainly numerous other benefits, they are arguably secondary.

> There do exist certain other definite benefits of IPv6 like possible
> use of Flow Specifications in the Flow Label,

At this point in time, there is still a lack of consensus on how the
Flow Label should be used. Or more specifically, there is as of yet no
driving application that has led the IETF to define how the bits will
be used.  Thus, pointing to the Flow Label as an argument to move to
IPv6 is unconvincing to most.

> decreased processing delay at routers, greater flexibility etc.

All useful benefits. But very questionable as to whether they are
significant enough *by* *themselves* to lead to adoption. That is why
I consider them secondary.

> This is not to say that the IPv6 is answer to all problems, but just

Yes indeed! A lot of folks have invested a lot of time and effort in
IPv6 getting it where it is today. They deserve thanks for their
efforts, and I thank them.

Thomas

---

From: RJ Atkinson <[email-masked]>
Date: Wed, 23 Aug 2000 11:00:39 -0400

>to signify the worth of the effort of those working on it.

        I've tried really hard to avoid this debate, because it is the
wrong forum and it hasn't been a particularly useful debate.  The signal
to noise ratio has been remarkably poor.

        The erroneous information quoted above is part of the frustration
of the folks, like me, who aren't zealots either way and are just
trying to grow The Internet.  Equally erroneous information emanates
regularly from certain anti-IPv6 zealots, so there are no saints here,
only sinners.  However, I've written code for no less than 3 IPv6
implementations, thus far, so I like to think that I'm plausibly 
well informed.

Point by point:
        - Until a spec exists that explains how to actually use the Flow
          Label (and implement that use in Verilog or software), it 
          is NOT a "definite benefit of IPv6".  It is a *potential* 
          *future* benefit of IPv6, but is not a "definite benefit" 
          at present.
        - Other than cisco, most router vendors implement their IP 
          forwarding in hardware, so the forwarding latency for IPv6
          is really identical to that for IPv4.  In the near term,
          many vendors have ASICs to forward IPv4 but rely on conventional
          CPUs and software to forward IPv6 -- in this situation IPv6
          forwarding is HIGHER latency than IPv4.  In the narrow case
          where a vendor uses software-based forwarding for both IPv4
          and IPv6, it is highly implementation-dependent which, if
          either, is lower latency.
        - Greater flexibility.  Too vague a claim to evaluate either way.

        I think it would be helpful if the advocates toned down their
marketing AND if the anti-IPv6 zealots toned down their anti-marketing.
Neither is helpful, IMHO.  It would be useful if people on either side
could have a calm discussion about reality over a meal or beverages.
The last time I was present at such, the results were decidedly mixed.

        Sigh.

Ran
[email-masked]

---

From: Masataka Ohta <[email-masked]>
Date: Thu, 24 Aug 2000 10:25:42 +0859 ()

Thomas;

> The

Huh? Compared to IPv4 equivalent, all the three features of IPv6
are unnecessarily complex without necessary functionalities.

> I agree with this, and suspect that much of the core IPv6 community

That's a silly statement.

Committees add all the features considered by some a modest but
necessary enhancement, of course.

							Masataka Ohta

---

From: Brian E Carpenter <[email-masked]>
Date: Thu, 24 Aug 2000 14:36:23 -0500

> are unnecessarily complex without necessary functionalities.

This is your opinion, not a statement of fact.
> That's a silly statement.

No it isn't.

   Brian

---

From: Masataka Ohta <[email-masked]>
Date: Fri, 25 Aug 2000 10:45:30 +0859 ()

Brian;

> This is your opinion, not a statement of fact.

Of course, it is not a statement of fact, because it is not authorized
by the committee.

And, you take, for example, the following recent comment of Sean
literally:

: Itojun -
: 
: >o The site may use the address prefix: 3ffe:0501:ffff::/48.  The address
: >  prefix was curved out from WIDE 6bone prefix.  The site MUST be
: >  renumbered, before the site gets connected to the worldwide IPv6
: >  network.
: 
: Shouldn't IPv6's much-trumpeted stateless autoconfiguration and
: renumbering scheme take care of that, well, automatically?

that real world operators are so happy with much-trumpeted stateless
autoconfiguration and renumbering features of IPv6.

Wow!

> > That's a silly statement.

For committees, of course, it isn't, because a committee can not
accept a statement of fact that the committee is silly.

							Masataka Ohta