Re: [AVTCORE] Regarding draft-ietf-avtcore-feedback-supression-rtp-15

["Van Caenegem, Tom (Tom)" <[e-mail]>]

Hi Magnus  (, Qin)


Version 15 makes the following three statements:


1)Section 3:

"When a receiver gets a RTCP TPLR message, it MUST follow the rules
for NACK suppression in RFC4585 [RFC4585]and refrain from sending a
feedback request (e.g., NACK or FIR) for the missing packets reported
in the message,which is dealt with in the same way as receiving NACK"

2)Section 3:

"A receiver may have sent a Feedback message according to the RTP/AVPF
scheduling algorithm of RFC4585 [RFC4585] before receiving a RTCP
TPLR message, but further feedback messages for those sequence
numbers SHOULD be suppressed after receiving the RTCP TPLR"


3)Section 7:

"Also note that endpoints that receive a Third Party Loss Report would
be well-advised to ignore it, unless the security is in place to
authenticate the sender of the Third Party Loss Report"


These statements are still not aligned with each other. 

1) -> indicates that a TPLR message always results in FB suppression (MUST), and aligned with RFC 4585

2) -> why does the case where a receiver sent a NACK before receiving a TPLR, represents an exception on the receiver behaviour defined in the 1st statement (SHOULD instead of MUST)

3) -> is effective a SHOULD for non-authenticated TPLR messages.
 


Magnus, from your statement below, I take it that you propose a receiver behaviour different from the one defined in RFC 4585 (so SHOULD suppress feedback instead of MUST suppress feedback in RFC 4585).

If you do this , it requires some explicit reasoning that explains this difference , and explicit indication that this behaviour is different from feedback suppression rule defined in RFC 4585.
Tom


-----Original Message-----
From: [e-mail] [mailto:[e-mail]] On Behalf Of Magnus Westerlund
Sent: zaterdag 10 maart 2012 11:38
To: IETF AVTCore WG
Subject: [AVTCORE] Regarding draft-ietf-avtcore-feedback-supression-rtp-15

Hi,

Qin Wu has been very diligent in addressing raised comments. I want to state that I believe that this latest version do address the ADs comments in a reasonable way. I do want to point out to the WG that the authors choice of how to resolve one issue was to remove the whole problematic sentence. I personally believe this is right, but if any in the WG thinks it is problematic then speak up during the IETF last call.

   In other words, receivers MAY ignore RTCP TPLR messages, but SHOULD
   react to them unless they have good reason to still send	
   feedback messages despite having been requested to suppress them.

Cheers

Magnus Westerlund
AVTCORE WG chair

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