Re: Mirja Kühlewind's No Objection on draft-ietf-rtgwg-rlfa-node-protection-10: (with COMMENT)

[Pushpasis Sarkar <[e-mail]>]

Hi Uma,

Many thanks for the comments..

For the clarification for everyone, the following text in section 2.3.4
already mention about the knob you requested..

"

Implementations MUST choose
   a default value for this limit and may provide user with a
   configuration knob to override the default limit.  Implementations
   MUST also evaluate some default preference criteria while considering
   a PQ-node in this subset.  Finally, implementations MAY also allow
   the user to override the default preference criteria, by providing a
   policy configuration for the same.

"

So there is two knobs this document specifies..
- A knob to set the limit to the number of nodes in the subset of PQ-nodes.
- A policy configuration to let user control which nodes will go in the
subset of PQ-nodes

Thanks
-Pushpasis

On Fri, Jan 20, 2017 at 1:36 AM, Uma Chunduri <[e-mail]>
wrote:

> One quick comment below  [Uma]:
>
>
>
> --
>
> Uma C.
>
>
>
> *From:* rtgwg [mailto:[e-mail]] *On Behalf Of *Pushpasis
> Sarkar
> *Sent:* Thursday, January 19, 2017 3:39 AM
> *To:* Mirja Kühlewind <[e-mail]>
> *Cc:* [e-mail]; rtgwg-chairs <
> [e-mail]>; The IESG <[e-mail]>; RTGWG <[e-mail]>
> *Subject:* Re: Mirja Kühlewind's No Objection on
> draft-ietf-rtgwg-rlfa-node-protection-10: (with COMMENT)
>
>
>
> Hi Mirja,
>
>
>
> Thanks for your comments once again.. Please find some more answers inline
>
>
>
> -Pushpasis
>
>
>
> On Wed, Jan 18, 2017 at 9:02 PM, Mirja Kühlewind <[e-mail]>
> wrote:
>
> Hi Pushpasis,
>
> thank for your replies. Please see below!
>
> Mirja
>
> On 18.01.2017 03:42, Pushpasis Sarkar wrote:
>
> Hi Mirja,
>
> Thanks a lot for the comments. And sorry for not being able to reply
> earlier.
> Please find some comments  inline.
>
> Thanks
> -Pushpasis
>
> On Mon, Jan 16, 2017 at 10:03 PM, Mirja Kuehlewind <[e-mail]
>
> <mailto:[e-mail]>> wrote:
>
>     Mirja Kühlewind has entered the following ballot position for
>     draft-ietf-rtgwg-rlfa-node-protection-10: No Objection
>
>     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
>     <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-rtgwg-rlfa-
> node-protection/
>     <https://datatracker.ietf.org/doc/draft-ietf-rtgwg-rlfa-
> node-protection/>
>
>
>
>     ----------------------------------------------------------------------
>     COMMENT:
>     ----------------------------------------------------------------------
>
>     Overall comment: This reads rather like an informational rfc; however
>     given that rfc7490 is standards track, I guess that's fine.
>
>     More specific comments:
>     - More abbreviations could be spelled out to make it easier to read.
>
> [Pushpasis] I will try to add as many as I can in the next version :)
>
>     - Not sure what section 3 tells me; but I'm also not an expert.
>
> [Pushpasis] Section 3 is about a using the same solution proposed to find a
> node-protected R-LFA path by running a forward-SPF on the PQ node(s) to
> select parameters of the same paths discovered, so that the computing
> router
> on discovering multiple R-LFA backup paths to a single destination can run
> some backup-path-selection policies on the same path parameters collected
> (while doing computing F-SPF) to select one or more best suited R-LFA
> backup
> paths for the destination. Hope it explains :) You may also want to refer
> to
> RFC7916 for more explanation.
>
>
> Still not clear to me. Anyway I'm not an expert and maybe I'm missing
> something. Or let me ask the questions differently: What does this part add
> to the rest of the doc and why is this a separate section?
>
> [Pushpasis] The solution proposed to solve the first problem in section 2
> (i.e. ensuring node-protection with R-LFA) can also be extended to solve
> another problem (i.e. collecting parameters used by
> backup-selection-algorithm RFC7916 wrt to R-LFA backup paths (this is more
> detailed in section 6.2.5.4 of RFC7916). Since the same solution in a
> extended form also solved a separate but related problem, this was curved
> out as separate section. In summary this document proposes to two separate
> but related problems and hence two different sections..  Hope I could
> answer this satisfactorily this time.. :)
>
>
>
>
>
>
>     - Also section 3: "As already specified in Section 2.3.4 to limit the
>     computational
>        overhead of the proposed approach, forward SPF computations MUST be
>        run on a selected subset from the entire set of PQ-nodes computed in
>        the network, with a finite limit on the number of PQ-nodes in the
>        subset."
>        I guess you don't need the upper case MUST here.
>
> [Pushpasis] Actually this was suggested to be exactly a MUST in WG
> discussions on the WG mail
>
>
> My point was, given this is a MUST in section 2.3.4 and this sentence
> starts with "As already specified in Section 2.3.4" it does have to be an
> upper case MUST here again (because it's correctly normatively specified in
> section 2.3.4). However not a big issue.
>
> [Pushpasis] Got it. Will do so..
>
>
>
>
>
>
>     - Also then in section 2.3.4: "To limit the computational overhead of
> the
>     approach proposed, this
>        document proposes that implementations MUST choose a subset from the
>        entire set of PQ-nodes computed in the network, with a finite limit
>        on the number of PQ-nodes in the subset."
>        Saying "this doc recommends" and "MUST" in the same sentence seem
>     inaccurate.
>
> [Pushpasis] Should I replace 'recommends' with 'specifies' then?
>
>     - And also section 2.3.4: Could you maybe suggest or discuss an
>     appropriate default value?
>
> [Pushpasis] I have myself implemented it for Juniper and the default value
> as
> 16. I can specify the same as a suggested default. But I am not sure it
> will
> be raise any concern in the WG or not. If you suggest, I can go ahead and
> put
> this in the next version.
>
>
> If you think this could raise any concerns in the wg, you should go back
> to the wg mailing list and ask for feedback/confirmation.
>
> [Pushpasis] I dont think it will raise a concern. Just wanted to avoid
> unwarranted discussion.. :) Anyways I will provide some text in the next
> version and ask WG to let know any comments or opinion.
>
>
>
> [Uma]: It’s important to have a knob here and as long as this is there
> it’s fine (and this aspect is clearly described). This purely depends on
> how big the ring is but this sounds fine.
>
>
>
> Thanks and Regards,
>
> -Pushpasis
>
>
>
>
>
>
> Thanks once again
> -Pushpasis
>
>
>