Subject: Consensus on IPv6 Addressing Architecture

From: Bob Hinden <[email-masked]>
Date: Tue, 27 Aug 2002 16:07:07 -0700

The IPv6 working group chairs belive there is a consensus to adopt the 
changes proposed to the mailing list on 09 August 2002 and to advance the 
document to Draft Standard.  The discussion on the mailing was subsequent 
to a discussion at the Yokohama IETF.

The changes were to modify the interface identifier uniqueness requirements 
(from link to subnet prefix) and to change the definition of Site-Local 
addresses to make the subnet field 54-bits (and eliminate the 38-bit zero 
field).  There was no disagreement to the subnet field change.

There was a discussion about the interface identifier uniqueness 
change.  One issue raised was about the operational complexity of having 
different nodes using the same interface identifier (in different 
subnet-prefixes).

The following text (changed lines marked by "|") resolves this issue:

   2.5.1 Interface Identifiers

   Interface identifiers in IPv6 unicast addresses are used to identify
   interfaces on a link.  They are required to be unique within a subnet |
   prefix.  It is recommended that the same interface identifier not be  |
   assigned to different nodes on a link.  They may also be unique over  |
   a broader scope.  In some cases an interface's identifier will be
   derived directly from that interface's link-layer address.  The same
   interface identifier may be used on multiple interfaces on a single
   node, as long as they are attached to different subnets.              |

The recommendation in the third sentence should accommodate the desired 
behavior while still relaxing the uniqueness requirement.

Subsequent to discussion on the proposed changes, questions were raised 
about the necessity of 64-bit interface identifiers and the /64 boundary in 
IPv6 unicast addresses.  The chairs reading of the discussion is that we do 
not believe there is a consensus to make changes in this part of the IPv6 
addressing architecture and the document can proceed.

A new version of the draft (-09) has been submitted to be published as an 
Internet Draft.  A few minor changes to the document were made in Appendix 
A to make the text consistent with the interface identifier uniqueness change.

The IPv6 working group chairs believe there is a consensus to advance this 
document to Draft Standard and plan to notify the Internet ADs accordingly.
		
Bob Hinden, Steve Deering, Margaret Wasserman
IPv6 Working Group Chairs

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From: Vladislav Yasevich <[email-masked]>
Date: Thu, 29 Aug 2002 15:23:51 -0400

Bob

I've been trying to figure all the imlication of the change
and have the following comments.

Bob Hinden wrote:
>   prefix.

Would it possible to add "for the link" at the end of this sentence.  I
think it would clarify where the subnet prefix is applicable in
normal situations.  It still leave door open for multi-link subnets.

>          It is recommended that the same interface identifier not be  |
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
I think the last sentence here clashes with the first statement of the
paragraph.  Interfaces are not attached to subnets, they are attached
to links...

Thanks

--vlad
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Vladislav Yasevich	       Tru64 UNIX - IPv6 Project Lead
Hewlett Packard 	       Tel: (603) 884-1079
Nashua, NH 03062	       ZKO3-3/T07