Subject: [Ice] trickle: replacing candidates

From: Peter Saint-Andre <[email-masked]>
Date: Wed, 7 Sep 2016 20:48:09 -0600

At IETF 96 [1], the WG discussed the topic of clarify what "replacing 
candidate" means (i.e., updating the priority and re-sorting the check 
list). To address this issue, I propose the following change to Section 8.1:

OLD

    Once this is done, the agent examines the check list looking for
    another pair that would be redundant with the new one.  If such a
    pair exists and its type is not peer reflexive, the pair with the
    higher priority is kept and the one with the lower priority is
    discarded.  If, on the other hand, the type of the pre-existing pair
    is peer reflexive, the agent MUST replace it with the new candidate
    it received, regardless of their priorities.

NEW

    Once this is done, the agent examines the check list looking for
    another pair that would be redundant with the new one.  If such a
    pair exists and its type is not peer reflexive, the pair with the
    higher priority is kept and the one with the lower priority is
    discarded.  If, on the other hand, the type of the pre-existing pair
    is peer reflexive, the agent MUST replace it with the new candidate
    it received (regardless of their respective priorities); this is done
    by setting the priority of the new candidate to the priority of the
    pre-existing candidate and then re-sorting the check list.

Peter

[1] https://www.ietf.org/proceedings/96/minutes/minutes-96-ice

---

From: Nils Ohlmeier <[email-masked]>
Date: Mon, 19 Sep 2016 20:29:35 -0700

> On Sep 7, 2016, at 19:48, Peter Saint-Andre <[email-masked]> wrote:
> 
> NEW
> 

Could someone please explain to me what the "type of a pair" means?

According to 5245 https://tools.ietf.org/html/rfc5245#page-33 candidate have types, but pairs don’t. I think I have an idea of what is meant by this, but I think this should be clarified in the text.

Further more I think that the paragraph above in section 8.1 kind of contradicts section 11 saying “...it does not require any change in processing.” I think an update of section 11 is due.

I can try to provide new paragraphs if that helps.

Best
  Nils Ohlmeier

---

From: Taylor Brandstetter <[email-masked]>
Date: Mon, 26 Sep 2016 10:31:03 -0700

The intended meaning of "type of a pair" was definitely "type of the remote
candidate of a pair". It just needs to be spelled out.

But what I'm a little confused about is "this is done by setting the
priority of the new candidate to the priority of the pre-existing
candidate." Isn't it the reverse? The pre-existing prflx candidate's
priority should be lowered to that of the signaled candidate.

On Mon, Sep 19, 2016 at 8:29 PM, Nils Ohlmeier <[email-masked]>
wrote:

> According to 5245 https://tools.ietf.org/html/rfc5245#page-33 candidate
> have types, but pairs don’t. I think I have an idea of what is meant by
> this, but I think this should be clarified in the text.
>
> Further more I think that the paragraph above in section 8.1 kind of
> contradicts section 11 saying “...it does not require any change in
> processing.” I think an update of section 11 is due.
>
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