Re: [Roll] WG Last Call draft-ietf-roll-trickle-mcast-02

I think others have covered most of what I wanted to say, but there is 
one point I want to highlight.

The issue relates to the following text:

    A scope larger than link-local MAY be used only when that scope 
corresponds exactly to the MPL
    domain.

There's no explanation on how a node would determine what scope 
corresponds to a MPL domain. How would it do that without being given 
some additional information from the edge-router/s. I think what is 
needed, here, is some multicast routing information from the edge-router/s.

One solution might be for a RPL root to advertise RIOs (in its DIOs), 
that give the multicast prefixes reachable outside of the RPL/MPL 
Domain. For example, a RPL root could advertise FF05::/16 to effectively 
indicate that site-local scope is wider than just the RPL Domain and 
that a router should encapsulate site-local multicasts, whether 
forwarding or sourcing them. Other multicasts could be sent 
un-encapsulated, however an implementation may still choose to 
encapsulate all non-link-local multicasts.

Of course, all this would be greatly simplified if IPv6-in-IPv6 
encapsulation of non-link-local multicasts was made mandatory within a 
"non-storing RPL domain" (MPL domain). Then there would be only one way 
to forward multicasts within such a domain and there would be no need 
for additional routing information.

- Dario

On 12-10-24 11:55 PM, JP Vasseur (jvasseur) wrote:
> Dear all,
>
> draft-ietf-roll-trickle-mcast-02  has been discussed on the mailing list and during WG meeting a number of time; the document is stable and
> has been implemented. Thus this starts a 2-week WG Last call ending on Nov 9 at noon ET. Please send your comments to the authors
> and copy the mailing list and the co-chairs.
>
> Thanks.
>
> JP.
>
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