Re: [Anima] Magnus Westerlund's No Objection on draft-ietf-anima-grasp-api-08: (with COMMENT)

Brian E Carpenter <> Thu, 03 December 2020 20:07 UTC

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To: Magnus Westerlund <>, The IESG <>
Cc:,,, Sheng Jiang <>
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From: Brian E Carpenter <>
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Date: Fri, 4 Dec 2020 09:07:11 +1300
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Subject: Re: [Anima] Magnus Westerlund's No Objection on draft-ietf-anima-grasp-api-08: (with COMMENT)
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Hi Magnus,

You raise an interesting point, but it's really about deployment
of the whole ANIMA infrastructure. We need the infrastructure to work
even when everything else is broken, which means it must have a
guaranteed slice of resource capacity and it should not exceed that
slice even when the autonomic system is fixing breakage.

If that doesn't work, GRASP sessions will start timing out, so the API
will report failures, starting with discovery failures**. That's where
the recommendation for exponential backoff comes in. But I think the
problem is deeper than the API.

** I've seen it happen, when running GRASP on a busy IETF wireless
network, back when we used to have meetings.


   Brian Carpenter

On 04-Dec-20 03:21, Magnus Westerlund via Datatracker wrote:
> Magnus Westerlund has entered the following ballot position for
> draft-ietf-anima-grasp-api-08: No Objection
> When responding, please keep the subject line intact and reply to all
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> Please refer to
> for more information about IESG DISCUSS and COMMENT positions.
> The document, along with other ballot positions, can be found here:
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> So I didn't have time to read your document in detail, thus I can easily have
> missed something.  Hopefully a bit of clarification on what I might have missed
> will resolve this issue.
> I do wonder over one aspect of this API surface. How does it handles when the
> GRASP layer is unable to send the messages in a timely fashion based on the API
> calls? Looking at GRASP I understand that it is using either UDP or TCP. The
> rate limiting of UDP does not appear to be more well specified that to follow
> RFC 8085 recommendations. So my concern here is that you actually have some
> risk of running into that the upper layer using this API tries to become a bit
> to active and do everything at once, thus resulting in that TCP congestion
> control and flow control might block timely transmissions, and for UDP the rate
> limiter / congestion control of the UDP messages. What happens in this API when
> this occurs?