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Re: site-local != NAT

2003-04-30 08:51:21
--On Wednesday, 30 April, 2003 07:09 -0700 Michael Thomas <mat(_at_)cisco(_dot_)com> wrote:

Keith Moore writes:
 > > Well, the pragmatic reality is to avoid using IP
 > > addresses as substitutes for endpoint
 > > identitifiers. Or maybe that's not pragmatic, but
 > > tough noogies; using IP addresses as endpoint
 > > identifiers is sloppy and generally a bad idea.
 >
 > ...and at this point the argument repeats, without your
having acquired  > any additional clue.

Maybe if you and Randy stopped playing elliptical
word games we could have some communication
here. If you have a point, make it.

Mike,

I disagree that they are playing word games. But let me try a different approach to the issue, partially to try to explain to you, at a bit more length, what I think they are talking about.

One of the key issues in this discussion has been whether it is reasonable to remove a previously-defined and standardized feature, especially one that has been widely deployed for some time, without strong justification. I think there is fairly wide agreement that is a bad idea, even if reasonable people might disagree as to which of those considerations apply to SL and to what degree.

Now, like it or not, we have a number of widely-distributed applications and other things, including some security protocols, that use IP addresses as endpoint identifiers. They do that, in part, because there is no more satisfactory candidate for an endpoint identifier. Certainly DNS names, with the current definition of the DNS, do not qualify as a satisfactory alternative and the number of standards-track alternatives that have received even moderate acceptance is, well, very small. Comparatively speaking, the number of network-seconds (or almost any other plausible measure you can think of) consumed by the collection of applications and other things that use IP addresses as endpoint identifiers significantly exceeds the number of network-seconds used for either referencing IPv6 addresses or using other types of standardized endpoint identifiers... keep in mind that, from at least one perspective on the situation, TCP is one of those things that uses IP addresses as endpoint identifiers.

And, of course it is trivial to make up names, and maybe even to pass them around. But there is quite a difference between that statement and a protocol that really uses such names as endpoint identifiers, carefully defines what those names are bound to and how and when they are unbound or refreshed, how they are exposed to the routing infrastructure without unacceptable layering violations, etc. Try doing some serious I-D writing and working through of the cases and transition issues.

So...

(i) If you want to get rid of the use of IP addresses as endpoint identifiers, let's see an I-D that describes a reasonable alternative, and how to get there from there, processed along the standards track. Asserting that IP addresses are not very good endpoint identifiers is not especially useful -- almost everyone agrees with you, but many of us are concerned about an operational network, and not, when it conflicts, philosophy.

(ii) Don't bother arguing that SL should be retained because it is standardized and entrenched and then turn around and argue for getting rid of IP addresses as endpoint identifiers without recognizing that usage are even more standardized and entrenched.

I continue to believe that there are serious and significant architectural issues underlying this discussion, ones that we, as a community, need to address and address soon. But, IMnvHO, complaining about those nasty applications that use IP addresses in ways that are, retrospectively, problematic is not only not a solution to the problems, but adds a lot of noise that gets in the way of looking at the architectural issues.

We now return you to your regularly-scheduled word games, sniping, name-calling, hyperbole, and flights of fancy :-(

    john




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