Subject: RE: RE: Prefix Delegation using ICMPv6

From: "Durand, Alain" <[email-masked]>
Date: Tue, 22 Aug 2006 23:31:10 -0400

> 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:

This is probably the crux of the issue. I believe that having
multiple IETF standardized ways to achieve the same thing is a bad idea.

   - Alain.

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From: Thomas Narten <[email-masked]>
Date: Thu, 24 Aug 2006 11:23:23 -0400

Boy, an awful lot of messages on this already, and what appears to be
a lot of repeating the same arguments, and not actually responding to
the concerns being raised (i.e., not listening). :-(

I guess I'll add my $0.02 as well.

> multiple IETF standardized ways to achieve the same thing is a bad idea.

I agree completely with this. Having multiple ways of doing the  same
thing ing mechanisms do not address it properly, and

3) the best way to address the problem is with a new mechanism (and
   it's better than other proposed ways of fixing the problem).

At this point, AFAIAC, you have not gotten past either points 1) or 2).

Thomas

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From: Thomas Narten <[email-masked]>
Date: Thu, 24 Aug 2006 11:23:23 -0400

I agree completely with this. Having multiple ways of doing the  same
thing inevitably increases complexity. It's usually a short-term
optimization that benefits one narrow constituency (in this case, it
would appear to be a group that doesn't like DHC for some vague
reason). But the cost of one groups simplifcation is additional
complexity for everyone else.

Is there an expectation that clients will only implement one of the
choices? Well, if so, the original problem isn't solved, since the
operator can't rely on the PD method being used exclusively. And if a
client implements both (since it's not sure which standard its peers
use), which one gets used? What if both are available? and provide
conflicting answers? etc., etc.

<[email-masked]> writes:

> The point that there is ALREADY at least one such case (node
> addressing) for which there is more than one standardized IETF way
> is irrefutable.

But it turns out there are different cases for these two. They do not
provide exactly the same service. DHC is critical for networks where
the routers/operators want to know which addresses are in use (e.g.,
they base access control on them, and/or do other types of
filtering). Or only blackhole traffic for addresses that are known to
be in use, in order to save bandwidth, etc.

This is not really possibly to do with stateless address
autoconfiguration, since a node picks its own address and isn't
required to tell anyone.

So, please explain, what technical justification PD has over DHC?

Thomas

evitably increases complexity. It's usually a short-term
optimization that benefits one narrow constituency (in this case, it
would appear to be a group that doesn't like DHC for some vague
reason). But the cost of one groups simplifcation is additional
complexity for everyone else.

Is there an expectation that clients will only implement one of the
choices? Well, if so, the original problem isn't solved, since the
operator can't rely on the PD method being used exclusively. And if a
client implements both (since it's not sure which standard its peers
use), which one gets used? What if both are available? and provide
conflicting answers? etc., etc.

<[email-masked]> writes:

> The point that there is ALREADY at least one such case (node
> addressing) for which there is more than one standardized IETF way
> is irrefutable.

But it turns out there are different cases for these two. They do not
provide exactly the same service. DHC is critical for networks where
the routers/operators want to know which addresses are in use (e.g.,
they base access control on them, and/or do other types of
filtering). Or only blackhole traffic for addresses that are known to
be in use, in order to save bandwidth, etc.

This is not really possibly to do with stateless address
autoconfiguration, since a node picks its own address and isn't
required to tell anyone.

So, please explain, what technical justification PD has over DHC?

Thomas