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RE: VoIP QOS best practices
From: Spencer.Wood () dot state oh us
Date: Mon, 10 Feb 2003 14:57:34 -0500

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

"Ray Burkholder" <ray () oneunified net>
Sent by: owner-nanog () merit edu
02/10/2003 02:21 PM
        To:     "Charles  Youse" <cyouse () register com>, "Alec H. Peterson" 
<ahp () hilander com>
        cc:     <nanog () 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

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

There are some other considerations involved but these are the main

Ray Burkholder

-----Original Message-----
From: Charles Youse [mailto:cyouse () register com] 
Sent: February 10, 2003 14:42
To: Alec H. Peterson
Cc: nanog () 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.


-----Original Message-----
From: Alec H. Peterson [mailto:ahp () hilander com]
Sent: Monday, February 10, 2003 1:40 PM
To: Bill Woodcock; Charles Youse
Cc: nanog () nanog org
Subject: RE: VoIP QOS best practices

--On Monday, February 10, 2003 10:19 -0800 Bill Woodcock 
<woody () pch net> 

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 H. Peterson -- ahp () hilander com
Chief Technology Officer
Catbird Networks, http://www.catbird.com

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