Re: [Roll] [roll] #132: draft-ietf-roll-trickle-mcast-04 - Clarify scope value of 3 - subnet-local

I realize I'm joining the conversation late.  I reviewed the document to see that "scop 3" was added, but I didn't read closely enough to notice that draft-ietf-roll-trickle-mcast-05 and draft-ietf-6man-multicast-scopes-00 are actually now in conflict with each other.

I'll explain why I think they are in conflict and then suggest how to fix the issue.

From draft-ietf-roll-trickle-mcast-05:

   When
   used with MPL, Realm-Local scope is administratively defined and used
   to define the boundaries of multicast message dissemination by MPL.

From draft-ietf-6man-multicast-scopes-00:

   Realm-Local scope is the largest scope that is automatically
   configured, i.e., automatically derived from physical
   connectivity or other, non-multicast-related configuration.

Specifically, "administratively defined" seems to me to be in direct conflict with "automatically configured".

I suggest fixing the problem with two updates.  First, the definition of "scop 3" in an IP-over-IEEE802.15.4 needs to be published, based on this text from draft-ietf-6man-multicast-scopes-00:

   The definition of any Realm-Local scope for a particular network
   technology should be published in an RFC.

I suggest:

   When used in an IP-over-IEEE802.15.4 network, "scop 3" is defined to include
   all interfaces participating in the IEEE802.15.4 multi-link subnet.

This text could be added to draft-ietf-roll-trickle-mcast-05, or to draft-ietf-6man-multicast-scopes-00 or published separately in yet another "world's shortest RFC".

Second, draft-ietf-roll-trickle-mcast-05 should be changed to read:

   When used with MPL, Realm-local scope is defined according to the
   underlying network technology; for example, [cite the IP-over-IEEE802.15.4
   definition].

As a further refinement, I suggest text be added to draft-ietf-roll-trickle-mcast-05 to the effect of:

   "scop 4" can also be used with MPL to cover deployments that use
   administratively defined scopes that cover, for example, subnets
   based on different underlying network technologies.

- Ralph

On Sep 13, 2013, at 2:53 PM 9/13/13, Michael Richardson <mcr+ietf@sandelman.ca> wrote:

> 
> Kerry Lynn <kerlyn@ieee.org> wrote:
>> Actually, that was my comment.
> 
> Oh, sorry for he confusion.
> 
>> It seems to me that the MPL draft and
>> draft-droms-6man-multicast-scopes-02 may be inconsistent in whether
>> Realm-Local scopes are administratively or automatically defined.
> 
> I believe that droms-6man-multicast-scopes-02 is supposed to say that
> scope-3 is to be defined automatically by a process to be described by a user
> of it.
> 
> And so trickle-mcast ought to define how to automatically define it.
> 
> I think that it ought to be defined to be the boundary of the DAG
> that contains the same (/64) prefix.
> 
> --
> Michael Richardson <mcr+IETF@sandelman.ca>, Sandelman Software Works
> IETF ROLL WG co-chair.    http://datatracker.ietf.org/wg/roll/charter/
> 
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