FW: Including RTCP report packets in IRR

Alan Clark alan at telchemy.com
Thu Dec 27 10:41:36 EST 2001


Paul/ Roni

I tried posting this to the SG16 reflector but it didn't get sent out
.......

Alan

-----Original Message-----
From: Alan Clark [mailto:alan at telchemy.com]
Sent: Wednesday, December 26, 2001 9:36 AM
To: 'ITU-SG16 at echo.jf.INTEL.COM'
Subject: RE: Including RTCP report packets in IRR



Paul/ Roni/ Frank

We have been introducing this general topic via ETSI TIPHON and more
recently presented at the IETF-52 AVT session.  We believe that RTCP stats
are not sufficient for VoIP purposes and also share the concern expressed by
others on this thread that it is vital to have several approaches to getting
data from the endpoints.

The approach we advocate is:-

(i) Calculate call quality metrics in the endpoint
It is necessary to consider the "burstiness" of packet loss in order to
assess impact on VoIP call quality - PLC is effective at hiding isolated
lost packets but not bursts.  VQmon (ETSI TS101 329-5 Annex E) is a
lightweight E model based algorithm for estimating call quality that
incorporates a burst packet loss model.

(ii) Recognize that there are several "audiences" for the data
In some networks both the network operations/ management and billing groups
would like to have access to call quality data however their requirements
are different.

- operations/management .. real time event reporting, SNMP access, test and
diagnosis
                        .. may need access to data during a call
                        .. needs support for fault isolation

- billing               .. end of call metrics
                        .. feed back through end of call messages

(iii) Provide several ways to get data out
We would like to see multiple ways of extracting data both from the
end-points and mid-flow.  These should include extended RTCP reports with
call quality metrics, end of call (DRQ or equivalent) and SNMP access.

Alan Clark
Telchemy

-----Original Message-----
From: Mailing list for parties associated with ITU-T Study Group 16
[mailto:ITU-SG16 at echo.jf.INTEL.COM]On Behalf Of Even ,Roni
Sent: Tuesday, December 25, 2001 9:33 AM
To: ITU-SG16 at echo.jf.INTEL.COM
Subject: Re: Including RTCP report packets in IRR


Paul,
Having a solution for H.323 may not solve the problem. RTP & RTCP are used
also in other protocols like SIP. At the last IETF meeting (IETF-52) the
topic was discussed in the AVT WG. Maybe we can see what will happen there.
I would like to point out that SNMP can be used to get part of the
information.
Roni Even

-----Original Message-----
From: Paul E. Jones [mailto:paulej at PACKETIZER.COM]
Sent: Monday, December 24, 2001 3:14 AM
To: ITU-SG16 at echo.jf.INTEL.COM
Subject: Re: Including RTCP report packets in IRR


Paul,

I suppose this is probably in need of clarification, but the assumption was
that if the call contained an audio session, the audio element would be
included.  Likewise for video, etc.  Unfortunately, there are a few fields
in H.225.0 that are labeled as "OPTIONAL" in the ASN.1, so implementers
assume that semantically they're optional, but that's not the case.  We
don't want to change the syntax (since we don't want to mandate the
inclusion of a field when the call doesn't have a session of that type), so
I suppose it would be nice to see a proposal for clarification of this
issue.

One other thought about the RTCP stats is that we report them in the DRQ
rather than the IRR.  One problem with IRRs is that if they are sent too
frequently, an extremely busy system can get bogged down processing those
messages.  I imagine that you'd want to set the IRR timer somewhere outside
the length of an average call.  Doing so, though, would mean you never get
stats for the average call.  So perhaps DRQ alone (or in addition to) the
IRR is the right approach.

Paul

----- Original Message -----
From: "Paul Long" <plong at IPDIALOG.COM>
To: <ITU-SG16 at echo.jf.INTEL.COM>
Sent: Tuesday, December 18, 2001 10:42 AM
Subject: Re: Including RTCP report packets in IRR


> Paul,
>
> Please note though that an EP is not required to include any media info in
> perCallInfo, i.e., audio, video, and data. I imagine that this was an
> oversight, but we ought to explicitly require v5+ EPs to report all
> currently active media sessions, including RTP.
>
> Paul Long
> ipDialog, Inc.
>
> -----Original Message-----
> From: Mailing list for parties associated with ITU-T Study Group 16
> [mailto:ITU-SG16 at echo.jf.INTEL.COM]On Behalf Of Paul E. Jones
> Sent: Tuesday, December 18, 2001 3:07 AM
> To: ITU-SG16 at echo.jf.INTEL.COM
> Subject: Re: Including RTCP report packets in IRR
>
>
> I completely support your idea.
>
> pj
>
> ----- Original Message -----
> From: <frank.derks at PHILIPS.COM>
> To: <ITU-SG16 at echo.jf.INTEL.COM>
> Sent: Monday, December 17, 2001 2:42 AM
> Subject: Including RTCP report packets in IRR
>
>
> > Dear all,
> >
> > RTP's specification mandates that the RTP ports, for a given
> > source/destination, are "co-located" with the RTCP ports. This
> > means the the report information about the RTP streams flow
> > between the communicating endpoints. Although this mode of
> > operation is intentional, it does make it difficult for 3rd
> > parties to monitor the statistics as perceived by the endpoints.
> > This can be particularly useful for network management where
> > one would like to be able to monitor whether the network
> > provides adequate quality.
> >
> > On way to access the RTCP information would be to route all the
> > RTCP traffic through some entity, but this also means that the
> > RTP will have to follow the same path through the network. And
> > this is not desirable.
> >
> > For H.323 there would be the option to include the report packets
> > in the "audio" element in the perCallInfo element in the IRR
> > message. This would allow for a Gatekeeper to get a hold of these
> > "vital" statistics.
> >
> > Any views?
> >
> > Regards,
> >
> > Frank
>



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