Subject: RE: [NSIS] AD Review comments on draft-ietf-nsis-req-07.txt

From: "Avella, Alejandro" <[email-masked]>
Date: Mon, 9 Jun 2003 08:38:05 -0600

Allison Mankin wrote:
>Second, speech in Internet phones is quite a lot less sensitive to delays
and jitter than
>often thought, due to the many good engineering designs in playout and
>speech cover that are known.  

From draft-ietf-nsis-req-07.txt, Page 27.

         1. The network supports a high proportion of real-time 
            traffic.  The majority of the traffic transported in the 
            wired part of the wireless network is speech, which is 
            very sensitive to delays and delay variation (jitter). 

Comment on Requirements document:
Consider being more specificic on the sentence above.  Voice requirements
for toll-quality are:
a) One way delay < 150 ms from ITU-T G.114 (Round Trip delay < 300 ms)
b) Jitter < 50 ms
c) Packet Loss < 10^-5

I obtained the above values from section 3.1 of the following paper.

M. Karam, F. Tobagi, "Analysis of Delay and Delay Jitter of Voice Traffic in
the Internet", Computer Networks 40 (2002) 711-726
http://www.stanford.edu/class/ee384b/reading/KaramTobagi.pdf

Alejandro Avella

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From: Henning Schulzrinne <[email-masked]>
Date: Mon, 09 Jun 2003 10:51:13 -0400

We've done recent measurements on this topic. See

http://edas.info/S.cgi?bibkey=Jian0305:Qos
http://edas.info/S.cgi?bibkey=Jian0305:Assessment
http://edas.info/S.cgi?bibkey=Jian0208:Comparisons

 From our experience, jitter itself does not matter, but it effectively 
translates into additional delay that is at least as large as the jitter 
range, but typically somewhat larger since playout delay algorithms 
can't be perfect.

The packet loss numbers cited below do not correspond to any recent real 
measurements. However, MPEG2 video is said to be significantly more loss 
sensitive than speech.

Avella, Alejandro wrote:
> Allison Mankin wrote:
>  >Second, speech in Internet phones is quite a lot less sensitive to 
> delays and jitter than
> Consider being more specificic on the sentence above.  Voice 
> requirements for toll-quality are:
> M. Karam, F. Tobagi, "Analysis of Delay and Delay Jitter of Voice 
> Traffic in the Internet", Computer Networks 40 (2002) 711-726 
> |
> |

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