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

[Uma Chunduri <[e-mail]>]

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]<mailto:[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]>
<mailto:[e-mail]<mailto:[e-mail]>>> wrote:

    Mirja Kühlewind has entered the following ballot position for
    draft-ietf-rtgwg-rlfa-node-protection-10: No Objection

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    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