Subject: [Isis-wg] Benoit Claise's No Objection on draft-ietf-isis-te-metric-extensions-09: (with COMMENT)

From: "Benoit Claise" <[email-masked]>
Date: Thu, 04 Feb 2016 00:41:12 -0800

Benoit Claise has entered the following ballot position for
draft-ietf-isis-te-metric-extensions-09: No Objection

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COMMENT:
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>From Nevil Brownlee (OPS DIR reviewer) and Stefano Previdi's discussion:

> I have one issue to raise: the last paragraph of section 2
> (introducing the metrics to for each of the new sub-TLVs) says that
> the values "MUST be calculated as rolling averages where the averaging
> period MUST be a configurable period of time."  This draft does not
> say how that interval will be configured.

the paragraph refers to section 5 “Announcement Thresholds and Filters”
where the thresholds and average values are explained. The specifics of
the configuration are not present because these are implementation
specifics aspects. 

The same has been done in RFC7471 which is the OSPF version of this
draft.

>  For proper operation,
> surely all participating IS-IS routers will need to use the same
> measurement interval?

Well, while it would make sense to use the same interval, it is not a
requirement and it’s possible to have a network where nodes use different
intervals to measure their links utilization. Also, as described in
section 5, the interval may vary and advertisements may be done
immediately in some cases.

>  I suggest that some text explaining this, and
> saying how a router's measurement interval can be checked by other
> routers, would be useful.

Here also there are no requirements for a router to be able to verify
which interval other routers used.

=====================================

Since that triggered some questions/discussions, a few sentences around
the following points would make sense from an OPS point of view:
- While it would make sense to use the same interval, it is not a
requirement and it’s possible to have a network where nodes use different
intervals to measure their links utilization
- There are no requirements for a router to be able to verify which
interval other routers used.

Regards, Benoit

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From: "Stefano Previdi (sprevidi)" <[email-masked]>
Date: Mon, 8 Feb 2016 16:50:13 +0000

> On Feb 4, 2016, at 9:41 AM, Benoit Claise (bclaise) <[email-masked]> wrote:
> 

we could indeed however I always feel reluctant to specify in a draft/rfc what it is not required.

s.