Re: [AVTCORE] RTP Topology addition (was: Design choice comments..._

Magnus Westerlund <magnus.westerlund@ericsson.com> Mon, 23 March 2015 18:15 UTC

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Date: Mon, 23 Mar 2015 13:15:25 -0500
From: Magnus Westerlund <magnus.westerlund@ericsson.com>
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To: "David Benham (dbenham)" <dbenham@cisco.com>
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Cc: 'IETF AVTCore WG' <avt@ietf.org>
Subject: Re: [AVTCORE] RTP Topology addition (was: Design choice comments..._
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On 2015-03-23 12:55, David Benham (dbenham) wrote:
> 
>> I think you need to start by actually describing in which way this
>> RTFS is different from the RTP mixer or the SFM. Is this really
>> different from what is already described, or simply a variant?
> 
> From the doc, the SFM appears to require, like the media switching
> mixer referenced, a collection of its own SSRCs (ie, terminating
> SSRCs on all legs), sending only a finite set of SSRC values
> downstream to any given recipient or a 'cascade link' to another box.
> 

The point of the SFM is that all SSRCs that exist upstream is projected
into the downstream. The point is that a selected set of the incoming
streams that are forwarded and rewritten according to need. SSRC
possibly, sequence number almost always needed, and often PT.

> 
> Is an SFM allowed per the definition to reuse the senders/upstream
> SSRCs, sending a potentially unlimited set of SSRCs downstream/to any
> given recipient?  Is allowing that a variant or?

Yes, that is possible. A point is that the SFM has a responsibility for
downstream congestion control.

Cheers

Magnus Westerlund

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