Subject: Re: [Ieprep] draft-ietf-ieprep-framework-02.txt

From: "Ayyasamy, Senthilkumar (UMKC-Student)" <[email-masked]>
Date: Fri, 1 Nov 2002 20:02:15 -0600

--- Henning Schulzrinne <[email-masked]> wrote:
> There have been approximately half a dozen published
> papers that have 
> attempted to characterize VoIP quality over various
> parts of the 
> Internet. Not surprisingly, there are generally
> three observations:
[...]
> - some are persistently bad to unusable, typically
> but not exclusively 
> for sessions between North America and Latin America
> and parts of Asia, 
> as well as between non-NA regions.
 sometimes even backbone(fig 9-14 in
http://www.ieee-infocom.org/2002/papers/355.pdf.) They
have shown that even over-provisioned paths provide poor 
VoIP performance by using some backbone traces. 
Even with good echo cancellation and G.711 encoder, some 
over-provisioned links provide less than 3.5 MOS level
(which is well below PSTN expectations.) But, I like their 
conclusion/ further work where they try to achieve higher 
MOS by just optimizing play out buffers( unlike 
run-of-the-mill statements like "I have QoS for rescue".) 
But still diffserv is an obvious approach here.

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