Re: A question on OAM section in draft-ietf-opsawg-l3sm-l3nm

[Greg Mirsky <[e-mail]>]

Hi Med,
thank you for your thoughtful consideration of my comments. I have another
question about the significance of the local-multiplier (formerly
detection-multiplier). The description seems not changed and it states:
                        "The detection interval for the BFD session
                         is calculated by multiplying the value of
                         the negotiated transmission interval by
                         the detection multiplier value.";
I will note that the detection multiplier value used by a BFD system to
calculate the Detection Time is not its local Detection Multiplier but the
value of the Detect Mult field in the received BFD control packet. In other
words, that is the local-multiplier of the remote BFD peer. Section 6.8.4
in RFC 5880 <https://datatracker.ietf.org/doc/html/rfc5880#section-6.8.4>
describes how the Detection Time is calculated for "classic" p2p BFD. Note,
the Detection Time for a MultipointTail in p2mp session is calculated
differently, according to Section 5.11 RFC 8562.

Regards,
Greg

On Fri, Sep 3, 2021 at 12:35 AM <[e-mail]> wrote:

> Hi Greg,
>
>
>
> FWIW, the agreed changes are now implemented in the module. You can track
> them at:
>
>
> https://github.com/IETF-OPSAWG-WG/lxnm/commit/9b97016743a355f2b7737288dfaedebcdc47c9b8
>
>
>
> Also, made the companion changes to the I-D:
> https://tinyurl.com/l3nm-latest
>
>
>
> Cheers,
>
> Med
>
>
>
> *De :* Greg Mirsky [mailto:[e-mail]]
> *Envoyé :* mercredi 1 septembre 2021 15:25
> *À :* BOUCADAIR Mohamed INNOV/NET <[e-mail]>
> *Cc :* Jeffrey Haas <[e-mail]>; [e-mail];
> opsawg <[e-mail]>; rtg-bfd WG <[e-mail]>
> *Objet :* Re: A question on OAM section in draft-ietf-opsawg-l3sm-l3nm
>
>
>
> Hi Med,
>
> thank you for your thoughtful consideration of my late comments.
>
>
>
> Regards,
>
> Greg
>
>
>
> On Wed, Sep 1, 2021 at 6:21 AM <[e-mail]> wrote:
>
> Re-,
>
> The IETF LC was actually closed since 2021-08-06.
>
> Even if the IETF LC is closed, the current BFD comments will be part of
> the comments we will be addressing in the next iteration. For your record,
> we have already recorded the name alignment fix, the missing default
> clause, holdtime explanation, and session type indication.
>
> If there are any other comments, please let us know.
>
> Thank you.
>
> Cheers,
> Med
>
> > -----Message d'origine-----
> > De : Jeffrey Haas [mailto:[e-mail]]
> > Envoyé : mercredi 1 septembre 2021 14:38
> > À : BOUCADAIR Mohamed INNOV/NET <[e-mail]>
> > Cc : Greg Mirsky <[e-mail]>; draft-ietf-opsawg-l3sm-
> > [e-mail]; opsawg <[e-mail]>; rtg-bfd WG <rtg-
> > [e-mail]>
> > Objet : Re: A question on OAM section in draft-ietf-opsawg-l3sm-l3nm
> >
> > Med,
> >
> > On Wed, Sep 01, 2021 at 06:48:43AM +0000,
> > [e-mail] wrote:
> > > Hi Jeff,
> > >
> > > Actually, except local-multiplier that we call detection-
> > multiplier,
> > > the same names are used in both drafts. We can fix that one.
> >
> > Certainly a start.
> >
> > > Please note that we are not using the interval-config-type choice
> > > given that the single case can be covered by setting
> > > desired-min-tx-interval and required-min-rx-interval to the same
> > value.
> >
> > This is true.  It's also true that that style entered the BFD YANG
> > model because a unified-only mechanism is what some vendors have
> > implemented.  If their implementations don't cover the split mode
> > you're requiring them to create a deviation.
> >
> > > It is then straightforward to
> > > map it the device module depending whether single-minimum-interval
> > > feature is supported or not. We don't want to complicate the
> > network
> > > view of the service with such device-level features.
> >
> > There is always a tension between service models and the needs of
> > the underlying device model.
> >
> > That said, you're losing the benefits of work already done.  As an
> > example, you're missing the default detection multiplier because
> > you're doing the work yourself rather than leveraging other work.
> > This means you're requiring the model users to always provision a
> > paramter that is usually left as a default.
> >
> > Clearly the BFD Working Group can't force you to use our work in
> > your model, especially if there are features that aren't a clean
> > fit.  That said, when it comes IETF review time, the choice to go-
> > it-alone will be noted so that the YANG doctors can do an
> > appropriately thorough audit.
> >
> > The BFD Working Group is also happy to help with review once it's
> > time.
> >
> > -- Jeff
>
>
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