From: none (alsontra@hotmail.com)
Date: Tue Nov 02 2004 - 15:53:24 GMT-3
Here some info I dug up a while ago...
****Voice Bandwidth Calculation Formulas
The following calculations are used:
Total packet size = (L2 header: MP or FRF.12 or Ethernet) + (IP/UDP/RTP
header) + (voice payload size)
PPS = (codec bit rate) / (voice payload size)
Bandwidth = total packet size * PPS
Sample Calculation
For example, the required bandwidth for a G.729 call (8 Kbps codec bit rate)
with cRTP, MP and the default 20 bytes of voice payload is:
Total packet size (bytes) = (MP header of 6 bytes) + ( compressed IP/UDP/RTP
header of 2 bytes) + (voice payload of 20 bytes) = 28 bytes
Total packet size (bits) = (28 bytes) * 8 bits per byte = 224 bits
PPS = (8 Kbps codec bit rate) / (160 bits) = 50 pps
Note: 160 bits = 20 bytes (default voice payload) * 8 bits per byte
Bandwidth per call = voice packet size (224 bits) * 50 pps = 11.2 Kbps
Ref:
http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a
0080094ae2.shtml
****Cisco Voice Codec Bandwidth Calculator****
Great tool for checking your work!
http://tools.cisco.com/Support/VBC/do/CodecCalc1.do
HTH
Alsontra
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of AK
Singh
Sent: Tuesday, November 02, 2004 9:39 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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