Re: [AVTCORE] Comments on draft-ietf-avtcore-feedback-supression-rtp-06.txt

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

Magnus,

If you want a view of the RAMS' authors, please check:
http://tools.ietf.org/html/draft-vancaenegem-avtcore-retransmission-for-ssm-00 

I did ask Qin to refer to this draft which provides a detailed description on how feedback suppression can work for RAMS topology.

In summary: 

The BRS sends a NACK or TPLR message to the DS, where the SSRC in this NACK or TPLR message is the one of the BRS. The DS forwards/reflects this message down on the primary SSM. This procedure will allow isolated feedback suppression, when RTP receivers only trigger FB suppression when recognising the SSRC as belonging to the BRS to which they report.

Tom  

> 4. Section 6.2: "If the BRS impacted by packet loss has been told the 
> actual packet loss, the BRS MAY choose to create new Third Party Loss 
> Report message and send it to the receivers in the downstream link.
> "
> 
> I don't understand how the BRS can inject any message into the SSM 
> tree, as the source anchor of the SSM tree is up at the multicast 
> source. Thus a BRS needs to tell the distribution source to send 
> something down stream on its behalf.
> 
> 
> 
> 
> [Qin]: It is possbile for BRS to tell the distrbution source to send 
> TPLR down on its BRS. My question is Is the BRS similar to 
> Distribution source as an intermediary between multicast source and
> 
> downstream receivers? Why BRS can not inject in between while 
> Distribution Source can?

My understanding what that the BRS is in fact not owner of their own SSM session, only help nodes that are receiver of the SSM session but not DS in it. And having the BRS send something to the DS which is only valid for its little part of a large SSM session is strange.

But RAMS authors view would be appreciated.