Subject: question regarding possible use of SLs in renumbering

From: Keith Moore <[email-masked]>
Date: Thu, 07 Nov 2002 12:10:05 -0500

question:

is it reasonable to assume that if a network is advertising one or more
global prefixes via ND/RD, that the scope of a 'site' for SL addresses
corresponds to the scope in which those global prefixes are advertised?

in other words, would it really be reasonable to assume that one could 
use SL addresses in some renumbering protocol and have them be able to 
reach all of the hosts/routers/apps that were affected by a prefix change?

Keith
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From: Margaret Wasserman <[email-masked]>
Date: Thu, 07 Nov 2002 14:31:53 -0500

Hi Keith,

The architecture does not require any correspondence between
site boundaries and the sets of links upon which a single global
routing prefix is advertised.

Margaret

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From: Thomas Narten <[email-masked]>
Date: Mon, 11 Nov 2002 13:01:16 -0500

> corresponds to the scope in which those global prefixes are

I think this would be an incorrect assumption. The question comes down
to "what is a site", and opinions vary. Some have argued that a site
is small area, like a building or campus. Others assume a site is as
large as the entire organization. Checking various documents,
addr-arch doesn't say what a site is, but
draft-ietf-ipngwg-scoping-arch-04.txt says:

           o Site-local scope, for uniquely identifying interfaces 
              within a single site only.  A "site" is, by intent, not 
              rigorously defined, but is typically expected to cover a 
              region of topology that belongs to a single organization 
              and is located within a single geographic location, such 
              as an office, an office complex, or a campus.  A personal 
              residence may be treated as a site (for example, when the 
              residence obtains Internet access via a public Internet 
              service provider), or as a part of a site (for example, 
              when the residence obtains Internet access via an 
              employer's or school's site). 

> reach all of the hosts/routers/apps that were affected by a prefix

I think one can imagine SLs being useful to avoid some of the
potential problems that renumbering lead to (e.g., like the need to
update config files). But the details of this have not really be
fleshed out (e.g., can this be done with SLs being also being in the
DNS? MUST they be?).  So I don't think one can say definitively, that
SLs *don't* or *can't* help. But I also don't believe one can say they
*do* help either, because the details have not been fleshed out,
AFAIK.

Thomas