G.729 voip bandwidth calculation in QoS

Unanswered Question
Jun 19th, 2008

I am trying to calculate how much bandwidth should put in the priority queue in the Frame Relay WAN for 8xG.729 calls.

I understand that the bandwidth for each call is (payload size+L2 overhead)*packets/s. For the G.729, by default it has 20 bytes payload and 50 packets per second.

But I am confused about the overhead.

In the QoS SRND3.3 page 1-15, it says MLP overhead is 13bytes, and FRF.12 has 8 bytes.

But from http://www.cisco.com/warp/public/788/pkt-voice-general/bwidth_consume.htm,

it says both MLPPP and FRF.12 have 6 bytes of overhead. In voice bandwidth calculator, it also says 6 bytes overhead for both MLPPP and RF.12.

So which one I should trust, the SRND or cisco web site?

Also for cRTP, all documents says the overhead is 2 bytes or 4 bytes. Then should I use 2 or 4?


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Chris Deren Thu, 06/19/2008 - 17:41

These values will not make a dramatic difference, simply use ~27 kbps per G729 call over Frame Relay, and multiply it by the number of calls you want to allow between the sites (I would suggest ensuring it by implementing CAC).




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