Re: [Roll] draft-ietf-6man-multicast-scopes updates RFC 4007 (Was Re: [roll] #132: draft-ietf-roll-trickle-mcast-04 - Clarify scope value of 3 - subnet-local)

[神明達哉 <[e-mail]>]

At Thu, 17 Oct 2013 09:10:50 -0700,
Ralph Droms <[e-mail]> wrote:

> Noting this conflict, I propose adding a bit of text to
> draft-ietf-6man-multicast-scopes to update RFC 4007 for consistency
> with RFC 4291:

I think making these consistent is a good idea.

> OLD:
>
>    o  The boundaries of zones of a scope other than interface-local,
>       link-local, and global must be defined and configured by network
>       administrators.
>
> NEW:
>
>    o  Admin-Local scope is the smallest scope that must be
>       administratively configured, i.e., not automatically derived
>       from physical connectivity or other, non-multicast-related
>       configuration.

I'm okay with the proposed text, but on a closer look I've noticed
a couple of subtle points you may want to consider:

- I see a slight difference between the OLD (RFC 4007) and NEW (RFC
  4291) even after fixing the obvious inconsistency, in that the NEW
  version does not necessarily say how the scopes larger than
  admin-local scope is configured; technically it only states
  interface-local and link-local (and "Realm-Local" if assigned)
  would not be automatically configured.  In fact, the global scope
  shouldn't be "administratively" configured, which is crystal clear
  from the OLD version, but not necessarily in the NEW version.

- should we worry about possible future updates to the addressing
  architecture and scope architecture documents?  If we keep these
  documents separately and have a copy of the text in both, we may need
  to update both copies when we need to make a change on this point as
  more "currently reserved" scopes are assigned.

These are probably too minor and maybe we can simply ignore the
subtlety.  If that's our consensus I'm okay with that.  But if we want
to address these points, maybe:

OLD:

   o  The boundaries of zones of a scope other than interface-local,
      link-local, and global must be defined and configured by network
      administrators.

NEW:

   o  The boundaries of zones of an interface-local, link-local, or
      global scope automatically derived from physical connectivity.
      For zones of other types of scopes, the IPv6 addressing
      architecture specification defines how their boundaries must be
      determined, whether automatically derived or administratively
      configured.

--
JINMEI, Tatuya