Re: [MMUSIC] Liaison Statement from 3GPP SA4 on RTCP Bandwidth Negotiation

[Gonzalo Camarillo <[e-mail]>]

Hi,

this is the link to the LS in the tracker:

https://datatracker.ietf.org/documents/LIAISON/liaison-2012-05-31-3gpp-mmusic-on-rtcp-bandwidth-negotiation-attachment-1.doc

Cheers,

Gonzalo

On 01/06/2012 2:46 PM, Miguel A. Garcia wrote:
> 3GPP SA4 has sent us an LS on RTCP Bandwidth Negotiation. I copy below 
> the text.
> 
> We should be able to provide them an answer in a reasonable time frame, 
> so please, review it and provide with comments to the list. The chairs 
> will compile a reply text.
> 
> The original document can be found at the 3GPP web site:
> http://www.3gpp.org/ftp/tsg_sa/WG4_CODEC/TSGS4_69/Docs/S4-120810.zip
> 
> /Miguel and Flemming
> -------
> 
> 3GPP SA4 uses the RTCP bandwidth modifiers (b=RS and b=RR) to control the 
> amount of RTCP bandwidth used in point-to-point VoIP and video telephony 
> sessions.  As these parameters were primarily designed for multicast 
> sessions, the calculations in section 2 of RFC 3556 apply to the total 
> RTCP bandwidth for the session, i.e., total bandwidth for all clients 
> sending/receiving RTCP traffic. However, there are no SDP Offer/Answer 
> models defined that use these parameters for the negotiation of the total 
> RTCP bandwidth for point-to-point sessions.
> 
> To clarify this, SA4 is planning to make the following recommendations in 
> our specifications:
> 
> 1.	The RS and RR values included in the SDP offer should be treated as 
> proposed values for the session and may be modified by the answerer 
> during session negotiation.
> 
> 2.	When generating the SDP answer, the answerer should include the RR and 
> RS values proposed in the SDP offer. The answerer may instead choose to 
> include RR and RS values lower than those proposed in the SDP Offer.
> 
> 3.	The RS and RR values included in the SDP answer should be treated as 
> the negotiated values for the session and should be used to calculate the 
> total RTCP bandwidth for all terminals in the session.
> 
> 
> 
> Actions:
> To IETF MMUSIC WG
> 
> ACTION: 	SA4 asks MMUSIC WG to review the above recommendations and 
> identify if there are any discrepancies with the practices or 
> understanding in the IETF.
>