Subject: RE: Limiting the Use of Site-Local

From: Dan Lanciani <[email-masked]>
Date: Mon, 28 Oct 2002 15:52:14 -0500 (EST)

I think it's great the folks are starting to consider the difficult problems
associated with site-local addresses in particular and scoped addresses in
general.  In the past these have been glossed over with hand-waving arguments
that scopes would ``just work'' with minimal application involvement and a
little DNS magic.

Before you try to solve the problems by effectively reducing scopes to a
degenerate case of one and restricting site-local addresses to sites with
no global addresses (or even with no external connectivity), please keep in
mind that site-local addresses have been offered up as the solution to a
number of other problems which themselves were difficult to hand-wave away.
For example, the ability to have long-term tcp connections within a site in
the face of global address renumbering has--given the lack of any protocol
or application support for that renumbering--been pushed onto site-local
addressing.  (The problem is hardly confined to tcp, but that's the usual
example cited.)

Any language that reduces site-local addresses to second-class citizens (or,
worse, implies that they should not be used concurrent with global addresses)
will give stack and application vendors an excuse to fail to support such
configurations.  I don't think you want to open such a huge can of worms as
it will entail revisiting every problem that has been ``resolved'' with an
admonition to simply use site-local addresses.

				Dan Lanciani
				ddl@danlan.*com
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From: Rob Austein <[email-masked]>
Date: Mon, 28 Oct 2002 16:47:53 -0500

> admonition to simply use site-local addresses.

If site-local was the answer, what were the questions?  (No joke intended)
Do you have a list?

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From: Margaret Wasserman <[email-masked]>
Date: Mon, 28 Oct 2002 16:55:47 -0500

>configurations.

What do stack and application vendors need to do to support site-local
addressing?

And what makes you think that they are doing those things now?

The majority of stack and application implementations with which I am
familiar make no distinction at all between site-local address and
globals.

This is appropriate if site-locals will be used only on non-globally
connected sites (so, effectively, site-local == global).

Margaret