Subject: scope zone ID zero as the default (for revision of ipv6-scoping-arch)

From: JINMEI Tatuya / 神明達哉 <[email-masked]>
Date: Mon, 02 Feb 2004 23:00:25 +0900

Hello,

(I hope you still remember this) during the wg last call for
draft-ietf-ipv6-scoping-arch-00.txt, you proposed to use the zone ID
value zero as the default with a higher requirement level:

> b) I have a more serious issue with the default zone. The text says in
>    several places that the zone index zero might be used to indicate
>    the default zone but it explicitely allows to use other values. In
>    section six, it says:

>       Similarly, an implementation may choose an index value other
>       than zero to represent the default zone.

>    I am not sure why this is helpful. Is there a particular reason why
>    we can not just say that the default zone is indicated by a zone
>    index which MUST (or SHOULD if we have to compromise) be zero?

And, if I remember the discussion correctly, the consensus was we
should mandate zero as the default.  So, I'd like to propose the
following changes:

============

In Section 6 (the 3rd paragraph of page 7), change

   An implementation should also support the concept of a "default" zone
   for each scope.  It is convenient to reserve the index value zero, at
   each scope, to mean "use the default zone".

to

   An implementation should also support the concept of a "default" zone
   for each scope. And, when supported, the index value zero at each
   scope SHOULD be reserved to mean "use the default zone".

And change the last paragraph of Section 6:

   An implementation may use any value it chooses
   to label a zone as long as it meets the requirement that the index
   value of each zone of all scopes be unique within the node.
   Similarly, an implementation may choose an index value other than
   zero to represent the default zone.

to

   An implementation may use any value it chooses
   to label a zone as long as it meets the requirement that the index
   value of each zone of all scopes be unique within the node and that
   zero SHOULD be reserved to represent the default zone.

============

Would you live with this?

I also slightly remember that someone in the Minneapolis meeting
pointed out that it might be a good idea to ask other implementors if
they use a non-zero value as the default.  So, I now would like to ask
the question here.  If anyone knows an implementation that uses a
different value as the default and especially if you object to
mandating the default value, please speak up.

Thanks,

					JINMEI, Tatuya
					Communication Platform Lab.
					Corporate R&D Center, Toshiba Corp.
					[email-masked]

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