VoIP QOS best practices

Mon Feb 10 19:57:34 UTC 2003

Also note that those sizes are for the voice part of the payload 
only....It does not take into account any payload/packet overhead...

We use G.711 quite a bit on our network, and are traffic flows are right 
around 80k...

Spencer

************************************************************
Spencer Wood, Network Manager
Ohio Department Of Transportation
1320 Arthur E. Adams Drive
Columbus, Ohio 43221 
E-Mail: Spencer.Wood at dot.state.oh.us
Phone: 614.644.5422/Fax: 614.887.4021/Pager: 866.591.9954 
************************************************************* 

"Ray Burkholder" <ray at oneunified.net>
Sent by: owner-nanog at merit.edu
02/10/2003 02:21 PM

        To:     "Charles  Youse" <cyouse at register.com>, "Alec H. Peterson" 
<ahp at hilander.com>
        cc:     <nanog at nanog.org>
        Subject:        RE: VoIP QOS best practices

G.711 gives you the 64kbps quality you get on a channel in a PRI line.
No compression is performed.

G.729 is a well accepted codec that performs compression, and with ip
packet overhead, uses about 16 to 24 kbps (can't remember which).  It
gives voice quality very close to G.711.

G.723 has a noticeable voice quality change, and is in the 6 to 8 kbps
range.

The optimal is G.729 for quality vs bandwidth issues. 

There are some other considerations involved but these are the main
ones.

Ray Burkholder

> -----Original Message-----
> From: Charles Youse [mailto:cyouse at register.com] 
> Sent: February 10, 2003 14:42
> To: Alec H. Peterson
> Cc: nanog at nanog.org
> Subject: RE: VoIP QOS best practices
> 
> 
> 
> Speaking of codecs, what are the primary variables one uses 
> when choosing a codec?  I imagine this is some function of 
> how much bandwidth you want to use versus how much CPU to 
> encode the voice stream.
> 
> C.
> 
> -----Original Message-----
> From: Alec H. Peterson [mailto:ahp at hilander.com]
> Sent: Monday, February 10, 2003 1:40 PM
> To: Bill Woodcock; Charles Youse
> Cc: nanog at nanog.org
> Subject: RE: VoIP QOS best practices
> 
> 
> --On Monday, February 10, 2003 10:19 -0800 Bill Woodcock 
> <woody at pch.net> 
> wrote:
> 
> >
> > It works fine on 64k connections, okay on many 9600bps 
> connections.  T1 is
> > way more than is necessary.
> 
> I'd say that largely depends on which codec you are using and 
> how many 
> simultaneous calls you will have going.
> 
> Alec
> 
> --
> Alec H. Peterson -- ahp at hilander.com
> Chief Technology Officer
> Catbird Networks, http://www.catbird.com
> 

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