Some more detailed responses in line...
- Ralph
On Aug 22, 2006, at 11:25 PM, <[EMAIL PROTECTED]>
<[EMAIL PROTECTED]> wrote:
Hi Alain,
Thanks for the quick e-mail. As one of the co-authors, I'd in turn
like to reply (and state that ICMPv6 PD is ANOTHER way to do IPv6
PD, NOT a replacement for the existing mechanism). FWIW, please see
comments in-line:
From: "Durand, Alain" <[EMAIL PROTECTED]>
Date: 2006/08/22 Tue PM 09:12:21 CDT
To: Syam Madanapalli <[EMAIL PROTECTED]>,
IETF IPv6 Mailing List <ipv6@ietf.org>
Subject: RE: Prefix Delegation using ICMPv6
"Currently proposed solution for IPv6 Prefix Delegation is based on
DHCPv6 protocol. We believe that in certain network topologies and
configurations where the CPE routers may not be capable or
configured
to use DHCPv6 and hence can not utilize the currently proposed ipv6
prefix delegation procedure. Therefore an alternate ipv6 prefix
delegation procedure that does not require or depend on the DHCPv6
protocol is needed."
Could you please elaborate on the above rationale for this work?
Alain, that seems to be a fair question. My first inclination is to
direct you to an e-mail I'd posted to this workgroup about four
weeks ago (25Jul06, 0742EST, quoted below):
"Good morning all. AFAIK, there is currently no defined way (other
than via DHCPv6) to do IPv6 PD. It may well be that between a PE
and CE, DHCPv6 is neither required nor desired, but PD is.
Without more detail about why DHCPv6 is "neither required nor
desired", it's hard to talk about your e-mail. I didn't pay close
attention; was there followup to your e-mail?
Over the past twelve months or so there has been some interest in
ICMPv6 PD expressed to me. I'm considering submitting a related
draft, and seeking a co-author. Kindly reply off-line."
While I welcome your question at the present time, I should say
that it would have also been welcomed when the above referenced
mail was first sent.
Using the DHCPv6 packet format, PD is a 2 packet exchange,
and nothing forces any implementation to use the rest of the DHCP
machinery.
The argument that CPE or routers do not implement DHCP is weak
because
they do not implement this new mechanism either...
IPv6 ND, the mechanism upon which our approach is based, is
implemented virtually ubiquitously, if not entirely so. Please see
the draft to see what modifications we propose to accomodate the
IPv6 PD requirement using ICMPv6.**
So if work need to be done, one could argue that implementing a
solution based on the DHCPv6
packet
format is faster as the mechanism is already standardized...
For "one to so argue" would be to do so incorrectly given the above.**
It is also true that DHCPv6 PD is already standardized (in fact, a
full six months before the standard that defines IPv6 PD
requirements in the first place).
WHile it is true that work on DHCPv6 PD began before the requirements
document, the timing of the publication of the two documents is an
artifact of the RFC publication process. The PD requirements doc was
fundamentally complete before the DHCPv6 PD RFC was published. The
IETF certainly considered the PD requirements doc in the process of
developing and publishing DHCPv6 PD.
The argument that "implementing a solution based on the DHCPv6
packet format is faster...", because DHCPv6 PD is standardized, is
false.
Maybe yes, maybe no. However, today we have a published standard,
that was developed through a process that considered several
alternatives (including ICMP) and which has been implemented by
multiple vendors. There is at least one open source implementation
available. These implementations have been shown to be interoperable
at the TAHI interoperability tests and are deployed in production today.
Even if the "mechanism" to which you refer is vanilla DHCPv6, AFAIK
there are NO vendors that implement the entire suite of DHCPv6
abilities. Do you know of any?
Yes, there are several including an open source implementation.
Further, sometimes customer requirements drive innovation (yes
sometimes, it is the other way around).
But we haven't seen those customer requirements.
Customer requirements/requests/demands for an alternative (non
DHCPv6-based) IPv6 PD mechanism are on the rise. We (co-authors and
I) propose one such way to do it.
Again, they would not have to implement the whole DHCPv6 machinery
if they do not want to.
Perhaps you are correct in this instance, though with the ICMPv6 PD
based approach, IPv6 PD could be done without it entirely.
I don't understand the advantage to avoiding DHCPv6 entirely. From
the network operator's point of view, you've got to do the same
amount of work for any form of PD: fundamentally configure the server
with the prefixes to be assigned. As I have argued before, we have
DHCPv6 PD implemented in IOS. It requires fewer than a handful of
CLI commands to configure and you would need the same number of
commands to configure ICMP PD.
From the implementor's point of view, I won't get into an argument
about lines of code...but my observation is that implementing DHCPv6
is not particularly onerous.
I implore you to read the draft in its entirety, as I/we do most
sincerely welcome the technical review of our proposed mechanism.
Best Regards,
Tim Enos
Rom 8:28
- Alain.
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