Re: [Roll] Last Call: <draft-ietf-roll-trickle-mcast-05.txt> (Multicast Protocol for Low power and Lossy Networks (MPL)) to Proposed Standard

[Ralph Droms <[e-mail]>]

draft-ietf-roll-trickle-mcast-05 and draft-ietf-6man-multicast-scopes-00 are in conflict with each other.

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 sharing a PAN ID.

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

PS I originally posted about this issue to the rool WG mailing list:
http://www.ietf.org/mail-archive/web/roll/current/msg08188.html.
After a discussion with Kerry Lynn, I made a change to the definition
of scop 3 for IEEE802.15.4.