Re: [MMUSIC] Empty candidate lists in ice-sip-sdp offers and answers

Suhas Nandakumar <suhasietf@gmail.com> Thu, 16 May 2019 20:58 UTC

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From: Suhas Nandakumar <suhasietf@gmail.com>
Date: Thu, 16 May 2019 13:58:01 -0700
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To: Flemming Andreasen <fandreas@cisco.com>
Cc: Roman Shpount <rshpount@turbobridge.com>, Christer Holmberg <christer.holmberg@ericsson.com>, mmusic WG <mmusic@ietf.org>
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Subject: Re: [MMUSIC] Empty candidate lists in ice-sip-sdp offers and answers
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On Sun, May 12, 2019 at 8:40 PM Flemming Andreasen <fandreas@cisco.com>;
wrote:

>
>
> On 4/29/19 5:27 PM, Roman Shpount wrote:
>
> On Sat, Apr 27, 2019 at 2:02 PM Christer Holmberg <
> christer.holmberg@ericsson.com>; wrote:
>
>> ...
>>
>> >NOTE: Since it is possible that no candidates were provided in the
>> offer,  or that all candidates in the offer
>> >where skipped due to unsupported address type or FQDN name resolution
>> failure, ICE nomination process
>> >can start with no remote candidates. This,  however, does not indicate
>> an immediate ICE nomination failure.
>> >See <<draft-holmberg-ice-pac>> for more details.
>> >
>> >In the Receiving the Initial Answer section I have added the following:
>> >
>> >NOTE: Since it is possible that no candidates were provided in the
>> answer, or that all candidates in the answer
>> >where skipped due to unsupported address type or FQDN name resolution
>> failure, ICE nomination process can
>> >start with no remote candidates. This,  however, does not indicate an
>> immediate ICE nomination failure.
>> >See <<draft-holmberg-ice-pac>> for more details.
>>
>> I think the text is confusing, because it starts talking about the ICE
>> nomination process. There are other things that happen before, including
>> the creation of candidate pairs.
>>
>> So, I think the text should say that the agent will not be able to create
>> candidate pairs, and it will not be able to start sending connectivity
>> checks. Instead it will wait for the peer agent to start sending
>> connectivity checks, that the agent will then process as peer reflexive
>> candidates.
>>
>
> I will try to come up with some text that uses the same terminology as RFC
> 8445.
>
> Do you have the suggested text ?
>

[Suhas] Roman, do you happen to have the suggested text ?

>
> >I wanted to get the group's opinion regarding:
>> >
>> >1. Allowing offers and answers with no candidates
>>
>> I am ok with the principle. There seem to be use-cases for it, so...
>>
>> Agreed.
>
> >2. Adding a reference to draft-holmberg-ice-pac regarding how such
>> session descriptions or session descriptions where all candidates were
>> rejected are handled.
>>
>> The reference in the text above is misleading, because to me it sounds
>> like PAC describes how to process offers/answers without candidates. PAC is
>> only about a timer.
>>
>>
> Maybe this draft should cover the situation when session description
> processing did not generate any candidates. The fact that ICE has some
> minimal run timer is not enough. We still need something that explicitly
> states that it is acceptable to run ICE nomination process without
> candidates since, as far as I know, nothing in RFC 8445 specifies if this
> is allowed or not.
>
> I am not in favor of adding a normative dependency to ice-pac at this late
> stage. Why do we need that ?
>
> Thanks
>
> -- Flemming (with chair hat on)
>
>
> Regards,
> ___________________________________________
> Roman Shpount | CTO | Cell: +1(202) 262-8672
> 4905 Del Ray Ave, Suite 300 | Bethesda, MD 20814
> TurboBridge
>
>
>
>
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