Re: [Teas] Mirja Kühlewind's Discuss on draft-ietf-teas-rsvp-te-scaling-rec-06: (with DISCUSS and COMMENT)

Mirja, Hi!

This was discussed in my response to Elwyn. I apologize for not responding
directly.

RFC2961 doesn't discuss what to do with the retransmissions after the retry
limit is reached. It doesn't discuss how retransmissions need to be paced
after the rapid retries are stopped. Section 2.3 (ver 7) of the current
draft clarifies this and proposes the use of a "not so rapid (30secs)"
retransmission interval.

There were a couple of questions from this section that you wanted to get
discussed:
----
(1) Why is there no termination criteria specified?
There is nothing new about Path and Resv messages getting transmitted
indefinitely (this is normal soft-state signaling behavior). All that is
being discussed in this section is how these transmissions get paced after
the rapid retry limit is reached. The slower timer transmission will go on
until either an ack is received (at which point the regular "refresh
interval" comes into play) or the corresponding LSP instance state is torn
down.

----
(2) Why couldn't the regular refresh interval be used for these un-acked
retransmissions?
The primary goal of the retransmission is to eke out an acknowledgement
from the neighbor as quickly as you can. You can use the same value as the
the regular refresh interval provided it is small enough (like in the case
of the conventional refresh interval of 30 secs) . However, we are
recommending the use of a "large refresh interval" (20 mins) in the RI-RSVP
technique -- we can't wait that long for retrying the transmission of an
unacked message.

Consider a rudimentary state machine with the following states (assuming
the defaults suggested in the Appendix of the draft):
- first retransmit (exponential back off)
- second retransmit (exponential back off)
...
- seventh retransmit (exponential back off)
- 30s retransmission
- 20m refresh (regular refresh timer)

At any point when the Ack is received, you transition to the 20m refresh
state.

---

Do these two responses adequately answer your questions?

Regards,
-Pavan

On Thu, Oct 5, 2017 at 7:57 AM, Mirja Kuehlewind (IETF) <ietf@kuehlewind.net
> wrote:

> Hi Pavan,
>
> I don’t see any changes in the new version that addresses may actual
> discuss on section 2.1.3 (now section 2.3). Can you please clarify?
>
> Thanks,
> Mirja
>
>
> > Am 28.09.2017 um 05:45 schrieb Vishnu Pavan Beeram <
> vishnupavan@gmail.com>:
> >
> > Mirja, Hi!
> >
> > Thanks for the review. We just posted a new revision (-07) to address
> the Gen-Art review comments. Please go through the new diffs (
> https://www.ietf.org/rfcdiff?url2=draft-ietf-teas-rsvp-te-scaling-rec-07)
> and let us know if additional changes are required.
> >
> > Also, please go through the responses provided to the other review
> comments and let us know if there are still any unanswered questions.
> >
> > Regards,
> > -Pavan
> >
> >
> >
> > On Tue, Sep 26, 2017 at 2:01 PM, Mirja Kühlewind <ietf@kuehlewind.net>
> wrote:
> > Mirja Kühlewind has entered the following ballot position for
> > draft-ietf-teas-rsvp-te-scaling-rec-06: Discuss
> >
> > When responding, please keep the subject line intact and reply to all
> > email addresses included in the To and CC lines. (Feel free to cut this
> > introductory paragraph, however.)
> >
> >
> > Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.
> html
> > for more information about IESG DISCUSS and COMMENT positions.
> >
> >
> > The document, along with other ballot positions, can be found here:
> > https://datatracker.ietf.org/doc/draft-ietf-teas-rsvp-te-scaling-rec/
> >
> >
> >
> > ----------------------------------------------------------------------
> > DISCUSS:
> > ----------------------------------------------------------------------
> >
> > I'm uncertain what section 2.1.3. actually recommends. My understanding
> is that
> > it is recommend to still send retransmit some message even if the Rl was
> > reached and to that every 30s basically forever. First of all I think
> this
> > still needs a termination criteria when to stop to try to retransmit
> finally.
> > And the I don't understand why this is needed, instead of e.g. just
> using a
> > larger Rl value? Can you please clarify!
> >
> >
> > ----------------------------------------------------------------------
> > COMMENT:
> > ----------------------------------------------------------------------
> >
> > I fully agree with the gan-art review (Thanks Elwyn!) and Alvaro, that
> this
> > reads from time to time like a BCP but is actually a extension
> specification. I
> > would strongly recommend to apply the changes proposed by the gen-art
> review,
> > and there is also a very detailed list of nits/edits that should
> probably be
> > applied. Please have a look at that!
> >
> >
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>