Subject: [AVT] Question on RTCP statistics processing

From: Flemming Andreasen <[email-masked]>
Date: Mon, 17 May 2004 17:26:48 -0400

Greetings

Let's say I have a unicast RTP session in "sendonly" or "inactive" mode
(per SDP), but nevertheless, somebody is sending me RTP packets. Do I
include those packets in my RTCP statistics (packets lost, jitter, etc.)
or do I throw them away before we even get to that point ? In other
words, is RTCP statistics processing affected by higher layer signaling
about the directionality of the RTP session ?

Thanks

        Flemming

_______________________________________________
Audio/Video Transport Working Group
[email-masked]
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From: Mark Baugher <[email-masked]>
Date: Thu, 20 May 2004 09:06:28 -0700

>about the directionality of the RTP session ?

I would say "no" based on some instrumentation work I and others had
done with the RTP MIB.  I would say that the RTP measurements should
be based on RTP activity to be useful and comparable.

Mark

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From: Stephen Casner <[email-masked]>
Date: Thu, 20 May 2004 12:57:22 -0700 (PDT)

Flemming,

> or do I throw them away before we even get to that point ?

I would say no.  In the scenaio you propose, your RTP socket might not
even be open for read, so you would not even know if anyone sent RTP
packets.

> In other words, is RTCP statistics processing affected by higher
> layer signaling about the directionality of the RTP session ?

I don't think this level of detail needs to be nor should be specified
in the RTP standard.  It is an aspect of application behavior.  In the
early MBone tools that operated without explicit session signaling
(other than an SDP in SAP), then applications would be expected to
show all participants and send RTCP for them.  However, in a telephony
app, you might receive packets from some source not even involved in
the session, perhaps even as a DoS attack.  Clearly you don't want to
report RTCP for that.

                                                        -- Steve

p.s. Now I can use the phrase "RTP standard" with its full meaning!

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From: Mark Baugher <[email-masked]>
Date: Thu, 20 May 2004 14:14:28 -0700

Steve,

>the session, perhaps even as a DoS attack.  Clearly you don't want to

I think you would for the purpose of being able to identify possible
causes of disruption - "post mortum" if not in real time.

Mark