Re: [Roll] [Anima] ACP RPL profile and dynamics

[Toerless Eckert <[e-mail]>]

On Thu, Sep 08, 2022 at 12:44:05PM +0200, Hendrik Mahrt wrote:
> > On the other hand, a more typical ISP situation is there is a router with
> > three or four WAN links, each of which is a p2p ethernet.  In that case,
> > there is really only one peer on each link, and it makes no sense not to have
> > a tunnel up on every interface.
> > 
> 
> I'm not quite sure how the type of media or its capability to broadcast
> interacts with RPL parent selection. The way I understand ACP, IPSec
> tunnels are established with all link neighbors of the same ACP domain.
> This is done prior to RPL coming into action.

Right. Just like any L2 security would happen before RPL exchanges messages.

> It is also necessary to
> exchange RPL ranks with all neighbors. How else would a node determine
> its parent(s)? I guess afterwards tunnels to neighbors that are neither
> parent nor child of a node could be closed again, yes.

Which IMHO would raise the problem of then being unable to discover all
RPL changes from a (closed) RPL neighbor, unless there are clear RPL procedures
that indicate whenever a RPL neighbor needs to actively reach out to another
RPL neighbor again (hence being able to have signals to re-create the ACP
tunnel).

> The wording in ACP Section 6.12.1.7 is "The DODAG version is only
> incremented under catastrophic events", therefore I was under the
> impression global repair would only be done in extreme circumstances,
> and not periodically.

So my "Root dies" could be seen as a catastrophic event. What then would
be the least-catastrophic event that could only be handled with periodic
version increase ?

Cheers
    Toerless

>  Hendrik