Subject: (IPng 7403) I-D ACTION:draft-ietf-ipngwg-scoped-routing-01.txt

From: [email-masked]
Date: Sun, 11 Apr 1999 14:20:40 -0400

A New Internet-Draft is available from the on-line Internet-Drafts
directories.  This draft is a work item of the IPNG Working Group of
the IETF.

	Title           : Routing of Scoped Addresses in the Internet
			  Protocol Version 6 (IPv6)
	Author(s)	: B. Haberman
	Filename	: draft-ietf-ipngwg-scoped-routing-01.txt
	Pages		: 7
	Date		: 07-Apr-99
	
This document outlines a mechanism for generating routing tables that
include scoped IPv6 addresses.  It defines a set of rules for routers
to implement in order to forward scoped unicast and multicast addresses
regardless of the routing protocol.  It should be noted that these
rules will apply to all scoped addresses.

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From: "Matt Crawford" <[email-masked]>
Date: Mon, 12 Apr 1999 11:07:38 -0500

This is a good first cut at a document that should definitely exist.
I think it needs elaboration or correction in a couple of directions.

Section 2:

>     -  Site boundaries cut through nodes

How about splitting this into three:

	Links belong to at most one site.
	Interfaces belong to the site of the attached link, if any.
	Nodes are part of all sites which their interfaces belong to,
	and no other sites.

>     -  A single interface can only be in one site

	An interface can be in at most one site.

In my mind, it would often be useful for links between two sites to
belong to neither.  Maybe a footnote is needed for subinterfaces (VCs
and the like).

Section 3

>    In a single site router, a routing protocol
>    can advertise and route all addresses and prefixes on all interfaces.

Except the link-local prefix, of course.

Section 4.2

> the router must perform the following :

Conceptually, yes.  But the effect can be achieved other ways.

>    code = 5 (Scope Mismatch).

I'm not convinced we *need* a new code.  Code 3 is for "any other
reason [than administrative prohibition or no route]."  If the
sending node has some sort of try-again smarts, it can easily notice
that the src & dst scopes are different.

Section 5

Here's a question: Were the various multicast scopes meant to be
strictly hierarchical?  They can't be if nodes are multi-sited,
unless you demand that a node-local multicast only reach (conceptual)
sockets bound to interfaces in the same site -- and I think that
would be a bad demand to make.  scop=2 (link-local) couldn't cross a
site boundary, by the proposed definition of site boundaries, but
scop=1 could, and in principle so could scop=3 and 4.  I think we can
live with that.

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