[VoiceOps] Question about Packet Jitter

Schwarz, Albrecht (Albrecht) albrecht.schwarz at alcatel-lucent.com
Tue Nov 2 04:32:23 EDT 2010

That's of course not really true, looks like you missed a lot of ITU-T docs.

You got to check out the
- Y.x-series
- G.x-series
- P.x-series
of ITU-T Recommendations.

At also the work in progress of SG12:

See e.g.
P.1010 : Fundamental voice transmission objectives for VoIP terminals and gateways 

or Drafts
P.VOIP-MM Q 2/12 	Measurement methodologies for P.VOIP
P.IPterm  Q 3/12 	Transmission characteristics for VoIP terminals

etc etc

> -----Original Message-----
> From: Hiers, David [mailto:David_Hiers at adp.com] 
> Sent: Montag, 1. November 2010 21:54
> To: Jim.Dalton at transnexus.com; Schwarz, Albrecht (Albrecht); 
> voiceops at voiceops.org
> Subject: RE: [VoiceOps] Question about Packet Jitter
> Before you get down into the weeds with the math...
> All the ITU docs that I've read portray the "network" as set 
> of "non-rtp-aware, forward-as-fast-as-you-can 
> router-type-things that probably have some qos capability".  
> The "edge" is implicitly defined as the first occurrence of a 
> jitter buffer.  
> As near as I can tell, there are no rtp jitter buffers in an 
> ITU "network" for which all this fancy math applies.  If you 
> transcode, scrub media with a ditech pvp, or otherwise 
> implement anything that knows it should generate an rtp 
> stream by sending a packet every X milliseconds, the ITU math 
> is bounded by that device.
> If the SBC in your example transcodes or has a 
> jitter/loss-concealment buffer, it *is* the edge, and you 
> cannot average the link jitters as described in the ITU docs.
> David Hiers
> ADP Dealer Services
> 2525 SW 1st Ave.
> Suite 300W
> Portland, OR 97201
> o: 503-205-4467
> f: 503-402-3277
> -----Original Message-----
> From: voiceops-bounces at voiceops.org 
> [mailto:voiceops-bounces at voiceops.org] On Behalf Of Jim Dalton
> Sent: Friday, October 29, 2010 6:43 AM
> To: 'Schwarz, Albrecht (Albrecht)'; voiceops at voiceops.org
> Subject: Re: [VoiceOps] Question about Packet Jitter
> > VoIP performance experts should be familiar with
> > 
> > - ITU-T Y.1541 concerning IPDV (IP packet delay variation = 
> jitter); 
> > there are many sections on IPDV, particularily also on "aggregated 
> > PDV";
> > 
> [JD wrote:] ITU-T Y.1541 "Amendment 1: New Appendix X - An 
> example showing how to calculate IPDV across multiple 
> sections" addresses my question.
> Thank you,
> Jim D.
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