Re: [Roll] Eliding-Info: Abbreviated Option and RCSS of an Option

To simply state:
I believe that using per option RCSS will have negligible/no improvement in
the control overhead.

We can keep per option RCSS just for flexibility and as Li mentioned, we
can keep simple/complex modes separated out in the draft. That is one way
to handle it if we still go for it.
But I still am in favor of not using per option RCSS at all.

On Thu, 4 Jun 2020 at 17:24, Pascal Thubert (pthubert) <pthubert=
40cisco.com@dmarc.ietf.org> wrote:

> Hello Rahul
>
>
>
> If the root always sends all options when it increments the RCSS then we
> get the behavior you’re proposing.
>

[RJ] Yes, this is what I would like to have (and is already clearly there).

> So maybe the possibility to advertise options separately is a capability?
>

[RJ] Yeah, if we still decide to go for per option RCSS, then yes,
capability can help.

>
>

>
> Pascal
>
>
>
> *From:* Roll <roll-bounces@ietf.org> *On Behalf Of *Rahul Jadhav
> *Sent:* jeudi 4 juin 2020 10:44
> *To:* Routing Over Low power and Lossy networks <roll@ietf.org>
> *Subject:* Re: [Roll] Eliding-Info: Abbreviated Option and RCSS of an
> Option
>
>
>
> Please find my response inline [RJ].
>
>
>
>
>
> RCSS can identify whole options in DIO, but it may be not flexible.
>
> Imagine the case that some reduced function device which don’t support MOPex/GCO,
> when root only update MOPex/GCO, even though RCSS increment, DIO can carry
> AOO and advertise the updated options, these RFDs could ignore the RCSS
> increment.
>
>
>
> [RJ] I would argue on the contrary that for an RFD the complexity of AOO
> is even less useful. Assuming that the protected options change rarely, how
> big is the utility for an RFD to know that only one of the protected
> options is changed and syncing it individually.
>
>
>
> Is it possible to add mode for RCSS? Simple mode means RCSS can only be a
> common counter for all the options. Complex mode means AOO can identify
> individual protected options?
>
>
>
> [RJ] I understand that the draft supports simple mode and complex mode
> (using AOO) is only an extension. But what I intend to say is that the
> complex mode may be a deterrent to anyone reading the draft. More
> importantly, I could not figure out much utility. The purpose of this draft
> is to reduce runtime network overhead. I would argue that complex mode will
> reduce the control overhead by a fraction of a percentage but requires more
> flash/ram.
>
>
>
>
>
>
>
>
>
> *From: *Roll <roll-bounces@ietf.org> on behalf of Rahul Jadhav <
> nyrahul@outlook.com>
> *Reply-To: *Routing Over Low power and Lossy networks <roll@ietf.org>
> *Date: *Thursday, June 4, 2020 at 15:45
> *To: *Routing Over Low power and Lossy networks <roll@ietf.org>
> *Subject: *[Roll] Eliding-Info: Abbreviated Option and RCSS of an Option
>
>
>
> Hello All, Pascal,
>
>
>
> Based on my understanding currently, the draft serves three purposes:
>
> 1. Helps elide common DIO options which rarely change
>
> 2. Helps elide common DAO options during route refresh cycles
>
> 3. Allow sync for individual protected options by assigning RCSS to an
> option (this implies the use of new AOO)
>
>
>
> Points 1 and 2 are quite clear and easy to follow.
>
>
>
> The whole complexity of the proposal lies in point 3 and from what I
> understand I believe the utility is not convincing enough for the amount of
> complexity it introduces.
>
>
>
> My understanding is that with AOO, it is possible that a Root assigns a
> different RCSS to individual protected options such that the downstream
> nodes can individually query and synchronize with any of that option on
> change.
>
>
>
> My rationale is that PIO/RIO/DODAG Configuration/MOPex/GCO options rarely
> change. IMO, if either of it changes then it is no big deal to advertise
> all the options. Rather than managing versions for each of these options,
> the RCSS can only be a common counter for all the options.
>
>
>
> I understand that RCSS of an option is "an extension" and it is possible
> to only use common RCSS. But I believe the whole RCSS of an option as an
> extension is adding to the complexity of the draft (introducing more
> scenarios to handle), and also making it difficult for the reader.
>
>
>
> Best,
>
> Rahul
>
>
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