Re: [AVT] comments on section 10 ofdraft-ietf-avt-rapid-acquisition-for-rtp-01

[Roni Even <Even.roni at huawei.com>]

Ali,
From figure 2 and the text that follows

" A Retransmission Source may equally act as a Burst Source.  The
   Retransmission Source may also incorporate the Feedback Target
   ([I-D.ietf-avt-rtcpssm] permits the feedback target to be a
   retransmission server, since it is a logical function to which RRs
   send their unicast feedback), and we will use the term Retransmission
   Server (RS) in the remainder of the document to refer to a single
   physical entity comprising these three entities that share state.
   Note that the same method (with the identical message flows) would
   also apply in a scenario where rapid acquisition is performed by a
   feedback target co-located with the media source."

I assumed that we are only dealing with the case that the RS is a single
entity and not three different entities with different addresses

I also thought that this was agreed in previous discussions

If my understanding is not correct I will review the draft since the current
text is not explicit enough to specify which part is doing each message. I
saw that RAMS-R is going to feedback target but RAMS-T is going to RS which
is not specifying a specific address according to you.

Roni

-----Original Message-----
From: Ali C. Begen (abegen) [mailto:abegen at cisco.com] 
Sent: Tuesday, June 16, 2009 10:00 PM
To: Roni Even; avt at ietf.org
Subject: RE: [AVT] comments on section 10
ofdraft-ietf-avt-rapid-acquisition-for-rtp-01

Remember that the RAMS-R (RR->RS) message is NOT on the retransmission
(unicast) session, it's on the primary session since it is sent to the
feedback target of the primary SSM session. Thus, the source port RR uses to
send RAMS-R "cannot" be assumed to be the destination port it wishes to
receive the unicast burst on.

If you agree with this statement, it is clear why we need port signaling.
Muxing will not help much here. It will just reduce the number of signaled
ports from 2 to 1.

-acbegen


> -----Original Message-----
> From: avt-bounces at ietf.org [mailto:avt-bounces at ietf.org] On Behalf Of Roni
Even
> Sent: Tuesday, June 16, 2009 10:08 AM
> To: avt at ietf.org
> Subject: [AVT] comments on section 10
ofdraft-ietf-avt-rapid-acquisition-for-rtp-01
> 
> Hi,
> 
> I looked at section 10 and have some comments
> 
> 
> 
> 1.       If RTP/RTCP multiplexing is used, there is no need for any
specific operation
> from the RR side. The RR sends the RAMS-R message to the RS from the port
it wants to
> receive the RAMS-I and RTP payload. The RS just sends the information to
the port from
> which it received the RAMS-R and not to the one in the SDP
> 
> 2.       In the case where there is no RTP/RTCP multiplexing, the RAMS-R
RTCP message will
> go to the RS and the RAMS-I will go to the port on the RR from where the
RAMS-R was
> received. For the RTP, the RR does not know if it has a NAT on the way to
the RS and
> should try to get a routable address (using STUN for example) and
providing the port to
> the RS ( we still need to agree on how to do it)
> 
> 3.       If the above two points are correct than the RR receive port in
the SDP is not
> really useful
> 
> 
> 
> Roni Even