From: Spolidoro, Guilherme (Guilherme.Spolidoro@unisys.com)
Date: Tue Nov 02 2004 - 19:35:03 GMT-3
Cisco has a calculator that is very useful, you can find the link doing a search on the archives. Anyway, my only comment is that you will see bandwidth requirements very similar if you're running voip on ethernet, serial (ppp, hdlc) and other transport modes. The one exception where you will see a much higher bandwidth requirement is when using ATM.
The main difference (I apologize for stating the obvious) is that ATM uses fixed cell size, while ethernet, ppp, etc has a variable frame size with an MTU large enough to fit a voip packet in one frame. ATM will need some cells to carry one voip packet...
I don't want to go into the details here but to point that this is a very important thing to consider if you're on a design phase. For example, sometime of us tend to think that G.729 uses an average of 24Kbps but it actually requires more like 80Kbps (forgot how much exactly-you can find on through the calculator) if you're running it through ATM. Again, not going into the specifics here, please do your own research...
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
AK Singh
Sent: Tuesday, November 02, 2004 10:39 AM
To: Group Study
Subject: Qos for voice and codec types
Hello,
I know that while applying QoS for different codec we have to consider
the BW requirement for the codec plus any overhead depending on how
the voice call is planned like Voip or Vofr. Can someone refer to some
good documentation which has different codec types and underlying
overhead.
regards
-Ak
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