Re: [Roll] Transit vs. Target in P DAO

[Rahul Jadhav <[e-mail]>]

Hi Pascal,

I have a few questions in the context (with respect to the problem
statement, not proposals):

Currently, the draft allows the Root to send multiple RTOs which could
contain the egress target and all the (immediate) children and siblings.
The VIO option list would contain all the hops on which to install these
target routes. Doesn't this already handle the problem statement you
mentioned? Using this the root can install routers not only to the egress
but also to its immediate children, isn't it?

Is the point to not install the route on behalf of egress but only for the
egress's children/siblings? Is this the objective to achieve?
It would be great to have a sample topology to base this discussion on.

One another point: The draft talks about "serial Track" .. is that
synonymous to the "serial path" you mentioned in your mail. Does serial
Track indicate a track with a single projected segment? Would be better to
have this term described in the terminology section in the doc. Thanks.

Best,
Rahul

On Tue, 22 Sep 2020 at 16:35, Pascal Thubert (pthubert) <pthubert=
[e-mail]> wrote:

> Dear all ;
>
>
>
> Say we are building a serial path using P DAO: in that case,  we are
> building a tunnel from the Track Ingress to the Track Egress, where the
> Track is signaled in the packet by the local RPLInstanceID in the RPI and
> the destination IPv6 address. The outer header may also have a SRH in case
> of non storing P DAO.
>
>
>
> In the current version of the P DAO draft we use a RPL Target Option (RTO)
> to signal the Track Egress and the new Via options (CMOs) to indicate the
> hops. But say we do not want to reach the Tunnel egress but one of its
> children or siblings. How can we signal that these guys are reachable over
> the tunnel?
>
>
>
> Proposal A)
>
>
>
> If we want to be able to signal that, it could be more consistent with RPL
> to use:
>
> - one or more RTOs to indicate the targets of the route, can be any of the
> children and siblings
>
> - Exactly one Transit Information Option (TIO) to indicate the tunnel
> egress
>
> - then one VIO or one or more SRVIOs (as we currently do)
>
>
>
> The result would be that the Track terminates at the “Parent” indicated in
> the TIO but can be used to reach any of the children and siblings indicates
> as targets
>
>
>
> Proposal B)
>
>
>
> Maybe we want to signal that only certain DetNet Flows should be placed in
> the Track. In that case, The RTO is not sufficient and we’d need the
> 6tuple. If we take that path, we’d need to create a new Flow option that is
> a Flow descriptor, in which case we’d get
>
> - one or more Flow Options to indicate which flows  are encapsulated in
> the Track
>
> - Exactly one RTO  (as we currently do) OR Exactly one TIO (as in Proposal
> A) to indicate the tunnel egress
>
> - then one VIO or one or more SRVIOs (as we currently do)
>
>
>
>
>
> What do you guys think?
>
>
>
> Pascal
>
>
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