various throughput/bandwidth questions

Unanswered Question
Jan 20th, 2008

Ok, what takes place when I make a call at 512kbps over ip through the public inet?

-is 512kbps just for the call initiation, what is that all about, does the video/audio packets travel at this speed minus or add overhead? Shouldnt it travel at whatever the allowable line speed is bw the near and far end?

-I take it you add 10-20% for layer 3 and 2 encap overhead?

-if I do a multipoint call at 512, is that 512 to each site?

-if I have a 3meg internet pipe, I should do no more than 1.5meg of h.323 at one time to account for overhead and other traffic?

-why do isdn calls perform better at equal or less speed, bc its a dedicated point to point established link?

-if I have a 100mbps link connecting my unit, is the data put on the line at 100meg or the call rate? If it goes by line speed, why even set a call rate? Since the data will travel at my near end various line speeds 100meg->1gig->3meg to isp->various carriers->far end. But I know there will be latency and delay with other traffic. On the public internet, shouldnt a user browsing the web flow just as fast as my video conference call? I guess what Im trying to say is, shouldnt the data travel as fast as the links bw the user and far end will allow over the public internet, account for end user bandwidth and in between congestion?

I hope these are some good questions and Im making sense. If someone knows books or sites for info to educate me, Im all ears. Thanks for the help.

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bwilmoth Fri, 01/25/2008 - 10:04

Bandwidth requirement depends upon the selection of codec. IF you are using g.711 it will take up to 84.4 kbps per call and for g.729 approx 24 kbs without crtp. with crtp these will be reduced to 64 and 8 kbps.


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