Subject: Re: [siprec] FIR vs. SIP INFO

From: "Charles Eckel (eckelcu)" <[email-masked]>
Date: Sat, 14 Jun 2014 04:51:38 +0000

Reviving a sleeping thread …

The sense of the room, as captured in the meeting minutes, was that we add
a requirement on the SRS to support both methods. Continuing the
discussion on the list resulted in only one addition comment, from Ram, in
support of this proposal.
With this in mind, I propose we append the following to section 8.1.7.1.1:

"To make sure a common mechanism exists between the SRC and SRS, the SRS
MUST support both mechanisms (FIR and SIP INFO), using FIR when negotiated
successfully with the SRC, and using SIP INFO otherwise."

Comments and other ideas welcome.

Cheers,
Charles

On 3/20/14, 8:03 PM, "Ram Mohan R (rmohanr)" <[email-masked]> wrote:

>I prefer option 2 as mandatory since SRS is the one that eventually looks
>at the media being recorded(RTP) and is the best one to decide on whether
>to generate a FIR or SIP INFO.  However we may also allow a SRC to
>generate a FIR/SIP INFO. So I prefer that we can keep MUST for option 2
>and MAY for option 1.
>
>I have a slightly different question on this -
>Do we want SRS(or SRC) to always generate both FIR and SIP INFO ? There
>may be cases where endpoint (UA) may support one or both of them. If a UA
>supports both of them it may result in a case where UA may re-transmit IDR
>frame twice (one on receipt of FIR and other on on receipt of SIP INFO).
>This is ok in principle but may lead to more network congestion due to
>bursty traffic. Is this some thing we should worry about ?
>
>Perhaps if there is a way SRS/SRC can find what method the UA prefers (FIR
>or SIP INFO) it can only generate that.
>
>Ram
>
>
>-----Original Message-----
>From: "Charles Eckel   (eckelcu)" <[email-masked]>
>Date: Friday, 21 March 2014 2:34 am
>To: "[email-masked]" <[email-masked]>
>Subject: [siprec] FIR vs. SIP INFO
>
>>To the best of my knowledge, this is the last open item in the protocol
>>draft. Here is the info from the slide presented at IETF 89 in London:
>>
>>FIR and SIP INFO requirements in SRC and/or SRS
>>------------------------
>>Section 8.1.7.1.1 SIP INFO for FIR
>>¨"XML Schema for Media Control² [RFC5168
>><http://tools.ietf.org/html/rfc5168>] defines an Extensible Markup
>>Language (XML) Schema for video fast update. Implementations are
>>discouraged from using the method described except for backward
>>compatibility purposes. Implementations SHOULD use FIR messages instead.
>>
>>NENA ICE-8 event feedback, do we need to say more? Options:
>>1.SRC MUST support both and provide interworking to what SRS supports
>>(and
>>an UA that does not support both MUST NOT use SIPREC?)
>>2.SRS MUST support both (and allow SRC to support both simultaneously?
>>And
>>how do you negotiation that ?)
>>3.Provide recommendations and leave as quality of implementation decision
>>(and live with interoperability issues?)
>>-----------------------------
>>
>>Discussion in room (from minutes:
>>http://www.ietf.org/mail-archive/web/siprec/current/msg03934.html)
>>- Paul K - no brainer, SRS is the powerful box - that is the place to put
>>requirements - 2 is preferable to 1 - 2 vs. 3, I'm not sure, kind of
>>inclined for 2 but not sure
>>- Chair: definitive is best for implementation
>>- Charles: option 3 is my suggestion (as the draft is), but could live
>>with option 2 - would appreciate some help with the text - need to think
>>about use cases - if a UA is capable of dealing with both, it can
>>simplify
>>for the SRS, but depends on capabilities of the SRC and SRS - if we can
>>do
>>better that is great
>>- Chair: let's have more list discussion because missing people - but in
>>favour of documenting one and generally in favour of having the server do
>>the work - tentatively think going in the direction of option 2
>>
>>Thoughts?
>>
>>Cheers,
>>Charles
>>
>>_______________________________________________
>>siprec mailing list
>>[email-masked]
>>https://www.ietf.org/mailman/listinfo/siprec
>

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From: "Ram Mohan R (rmohanr)" <[email-masked]>
Date: Sat, 28 Jun 2014 16:54:05 +0000

Proposed text looks good to me.

Ram

-----Original Message-----
From: "Charles Eckel   (eckelcu)" <[email-masked]>
Date: Saturday, 14 June 2014 10:21 am
To: Ram Mohan Ravindranath <[email-masked]>, "[email-masked]"
<[email-masked]>
Subject: Re: [siprec] FIR vs. SIP INFO

---

From: Paul Kyzivat <[email-masked]>
Date: Sat, 28 Jun 2014 14:07:30 -0400

> Proposed text looks good to me.

+1