[asterisk-users] Bandwidth requirements

[omar parihuana]

For bandwidth requeriments don't forget Layer 2 overhead. I.e
Frame-relay overhead is lower than Ethernet overhead.

Rgds.

On 10/5/06, Jay R. Ashworth <jra at baylink.com> wrote:
> On Thu, Oct 05, 2006 at 09:44:56AM +0100, Brian Candler wrote:
> > A 20ms packet duration means that 20ms of audio is stuffed into one IP
> > packet. Since each packet carries 1/50th of a second of audio, that means
> > you're generating 50 packets per second for each channel.
> >
> > With g729 your audio is 8000 bits per second.
> >
> > The overhead on each packet is 20 bytes (IP) + 8 bytes (UDP) + 12 bytes
> > (RTP) = 40 bytes or 320 bits.
> >
> > So your bandwidth requirement per channel is:
> > - 8000 bits per second for payload
> > - 320x50 = 16000 bits per second for overhead
> > making a total of 24000 bits per second.
> >
> > 20 simultaneous calls is therefore 480,000 bits per second.
>
> A reminder: much equipment, particularly low end/consumer equipment,
> chokes *much* faster on high PPS than it does on high BPS.
>
> While short packets are good for latency, they do impose stricter
> engineering evaluation requirements on the other links in your chains.
>
> Cheers,
> -- jra
> --
> Jay R. Ashworth                                                jra at baylink.com
> Designer                          Baylink                             RFC 2100
> Ashworth & Associates        The Things I Think                        '87 e24
> St Petersburg FL USA      http://baylink.pitas.com             +1 727 647 1274
>
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>          they stop having sex with you."  -- Jennifer Crusie; _Fast_Women_
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-- 
Omar E.P.T
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