[TriLUG] Some basic * questions

[Aaron S. Joyner]

Jon Carnes wrote:

>Come on now, Mark! We have a lot to add to a conversation like this
>(when we aren't too busy deploying Asterisk in the *Real World* to read
>the list...)
>
>Aaron is quite correct... academically... about bandwidth used by G711
>and G729 codecs. However in the real world we see rates of around 12 to
>20 kbs for typical G729 connections. In fact we regularly use 20kbs as
>our benchmark and we have never overshot that mark. 12kbs is much more
>typical.
>
>I'm sure Aaron knows why the real world scenario is much less - and I'll
>give him a moment of silence to illuminate us! :-)
>  
>
So where are you measuring that 20kbs?  If you're measuring it as 20kbs 
of layer2 bandwidth consumed (ie. ethernet frames, what ifconfig, 
iptables, or the interface counters on a switch or router will show 
you), you'll see I cited the upper bound as 23.2kb/s.  This accounts for 
the MAC header as well as the IP/UDP header.  The reason you're probably 
seeing 12kbs as a low-end average is things like VAD or G.729b (aka 
silence suppression) that knocks out about 50% of the bandwidth for your 
average conversation.

Aaron S. Joyner

>
>On Wed, 2006-05-31 at 12:29, Mark Turner wrote:
>  
>
>>Yeah ... what he said!
>>
>>Mark
>>
>>Aaron S. Joyner wrote:
>>    
>>
>>>Mark Turner wrote:
>>>
>>>      
>>>
>>>>Comments below.
>>>>
>>>>Brian Henning wrote:
>>>>
>>>>        
>>>>
>>>>>I figure the easiest way is to set up an Asterisk server here, attach 
>>>>>it to our existing PBX to show up as another extension, and push an 
>>>>>asterisk session (is that good terminology?) through an SSH tunnel 
>>>>>(or is that a bad idea?) to the remote employee's broadband-equipped 
>>>>>machine, which will sport a cheap headset/boom mic arrangement.
>>>>>          
>>>>>
>>[miscellaneous geek-prize-winning wisdom snipped]
>>    
>>
>
>A link - submitted for your approval. 
>(and hidden at the end of the email):
>
>http://www.cisco.com/warp/public/788/pkt-voice-general/bwidth_consume.htm
>
>Jon
>
>  
>