Re: [Detnet] Regarding the model for Active OAM packet

Hi Mach,
thank you for your attention to my comment and the most expedient response.
I don't find the DetNet Associated Channel defined in
draft-ietf-detnet-dp-sol-mpls and thus I assumed that OAM packets that
follow the data packet encapsulation defined in that draft use PW ACH as
defined in section 5 RFC 4385: True, it includes 8 bits-long Reserved field
that may be defined as OAM Sequence Number but that had not been discussed.
One is certain, existing nodes do not check the Reserved field. And without
a field to hold the sequence number, PREF will not handle the OAM packets.
Another question, additional processing and amount of state introduced in
the fast path by the fact that OAM's Sequence Number will have different
length and location in d-CW (differentiating cases by the first nibble).
Now, if we step back from DetnNet in MPLS data plane encapsulation, why the
control-word, as I understand, is configurable? I think that the Sequence
Number is not configurable, nor the first nibble. What do you think?

Regards,
Greg

On Tue, Sep 18, 2018 at 7:48 PM Mach Chen <mach.chen@huawei.com> wrote:

> Hi Greg,
>
> The MPLS DetNet header is defined as below:
>
> grouping mpls-detnet-header {
>     description
>         "The MPLS DetNet encapsulation header information.";
>     leaf service-label {
>       type uint32;
>       mandatory true;
>       description
>         "The service label of the DetNet header.";
>     }
>     leaf control-word {
>       type uint32;
>       mandatory true;
>       description
>         "The control word of the DetNet header.";
>     }
>   }
>
> Although do not consider Active OAM when design the above
> mpls-denet-header,  seems that it can cover Active OAM case as well. No
> matter a normal DetNet packet or an Active OAM packet, there should be a CW
> field, just as defined above.
>
> For normal DetNet packets, the CW is the d-CW as defined in the
> draft-ietf-detnet-dp-sol-mpls.
>
> For OAM packets, the CW is the "DetNet Associated Channel".
>
> Best regards,
> Mach
>
>
> > -----Original Message-----
> > From: detnet [mailto:detnet-bounces@ietf.org] On Behalf Of Greg Mirsky
> > Sent: Wednesday, September 19, 2018 3:17 AM
> > To: János Farkas <Janos.Farkas@ericsson.com>
> > Cc: DetNet WG <detnet@ietf.org>; detnet-chairs@ietf.org
> > Subject: Re: [Detnet] WG adoption poll draft-geng-detnet-conf-yang
> >
> > Hi Janos, et. al,
> > the mpls-detnet-header container is based on the solution described in
> > draft-ietf-detnet-dp-sol-mpls. Analysis of active SFC OAM in the proposed
> > MPLS data plane solution in draft-mirsky-detnet-oam points to the
> potential
> > problem as result the fact that OAM packet doesn't include d-CW. I
> believe
> > that this question should be discussed and, if we agree on the problem
> > statement, properly resolved. Until then, I do not support the adoption
> of
> > the model that may not be capable to support active OAM.
> >
> > Regards,
> > Greg
> > On Tue, Sep 18, 2018 at 12:03 PM Janos Farkas <Janos.Farkas@ericsson.com
> >
> > wrote:
> > >
> > > Dear all,
> > >
> > > This is start of a two week poll on making
> > > draft-geng-detnet-conf-yang-04 a working group document. Please send
> > > email to the list indicating "yes/support" or "no/do not support".  If
> > > indicating no, please state your reservations with the document.  If
> > > yes, please also feel free to provide comments you'd like to see
> > > addressed once the document is a WG document.
> > >
> > > The poll ends Oct 3.
> > >
> > > Thanks,
> > > János and Lou
> > >
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> > > detnet@ietf.org
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