Subject: Re: Fwd: IPv6 Scoped Addresses and Routing Protocols

From: Brian E Carpenter <[email-masked]>
Date: Sun, 30 Jun 2002 18:49:44 +0200

[email-masked] wrote:
> 
> >> >> SLs without
> >> >> site-ids cause problems for distributed applications.
> >> >Only if they leak, which the scope rules prevent.
> >>         given the common leakage of net 10 addresses (routes, packets
> >>         with net 10 src/dst, and DNS records), i don't feel confortable
> >>         with "only if they leak".  they will leak.
> >Is that any reason to make them meaningful once leaked?
> 
>         sorry for confusion, i vote for killing sitelocal entirely.

This (if it's still possible) would certainly resolve the problem, but
would leave open Keith's question about how to allocate a prefix for
disconnected sites (especially those which don't have even a single
IPv4 address and therefore an implied 6to4 prefix).

  Brian

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From: [email-masked]
Date: Mon, 01 Jul 2002 15:02:47 +0900

>IPv4 address and therefore an implied 6to4 prefix).

	it think i have already answered that question in the past:
	draft-itojun-ipv6-local-experiment-02.txt

itojun

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From: Robert Elz <[email-masked]>
Date: Mon, 01 Jul 2002 14:44:35 +0700

Date:        Mon, 01 Jul 2002 15:02:47 +0900
    From:        [email-masked]
    Message-ID:  <[email-masked]>

  | 	it think i have already answered that question in the past:
  | 	draft-itojun-ipv6-local-experiment-02.txt

Hmm - this is the (relevant) answer from your draft ...

  2.4.  Completely disconnected site

  If the site has no external IP connectivity, the site may use site local
  address space.

What such a site would do if it there were no site local addresses isn't
answered.    But this is not really relevant, as it is already quite clear
from this discussion that site local addresses are not going away.  At most
they may be modified a little.

wrt your draft, in advising against site local addresses, you make three
points ...

  o Site-local addresses are "scoped" address, while global addresses are
    not.

  o Configuration must correctly identify site border routers.  This is an
    additional requirement.

  o There are proposals on scoped routing exist [Deering, 2000] , however,
    implementation status is still rather disappointing.

For a disconnected site, the fact that site locals are scoped isn't really
very important, as there's only one scope (the site itself).   That is, for
this purpose, a SL addr is the same as a global (which also has one scope).

There are no site border routers for a disconnected site.

Routing of SL's in a disconnected site is identical to routing globals.

Where your draft is offering advice on how to get addresses, for a site
that can get some kind of connectivity, it is fine, and I certainly agree
that such sites should use global addresses - but it offers nothing much
useful at all as regards site local addresses, and certainly provides no
answers at all for how to handle a world in which SL's did not exist.

kre

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From: Keith Moore <[email-masked]>
Date: Mon, 01 Jul 2002 10:22:39 -0400

> this purpose, a SL addr is the same as a global (which also has one scope).

it's almost the same.  

first, completely isolated sites aren't as interesting as sites that do
have some connection to other sites - just not to the public Internet.
and the other sites might have external connections...)  as we learned
with RFC 1918, sooner or later many isolated nets will want to connect
to other sites.

the second difference with SLs is in application policy - an application
that is written to avoid use of SLs (because they are ambiguous) may not
work on a net that uses only SLs.

Keith