[VOIPSEC] [CAnet - news] Assessing Skype's network impact

[Gustavo Daniel Villarreal]

If the figures in the article reflect actual bandwidth plus overhead usage,
then Skype's bandwidth usage is fairly typical. Overhead for VoIP calls can
be well over 200%. A typical G.729 over Ethernet or Frame Relay will consume
30kbps, and 28kpbs over PPP (one way, assuming 50 packets per second), which
is quite a bit more than the 8kbps of the actual codec data. Applying IP
Header Compression on PPP links, this overhead can be reduced to 14kbps
total, a figure that is still well over the 8kbps of actual codec data.

If the article's figures don't take overhead into account, then yes, wow it
is a lot of bandwidth. Then again, Skype's perceived quality is much higher
than G.729, and is encrypted.




On 12/19/05 6:00 AM, "Voipsec-request at voipsa.org"
<Voipsec-request at voipsa.org> wrote:

> I wasn't aware that Skype used so much bandwidth! "33K to 46Kbps" IS a
> lot for a voice call, and as you say, this would eat up bandwidth. Of
> course this is only a problem due to the limited upload stream on your
> office ADSL line. Nevertheless, such a high bitrate would still cause
> problems.
> 
> The G.729 codec in fact uses only 6.4 - 11.8kbps bandwidth per call, and
> is a much better demonstration to customers of VoIP potential (there's
> nothing like a dropped call/low audio quality to send a customer
> running, screaming out the door!) I have found that codecs like G.711
> (which is 64kbps) can only manage about 2 concurrent calls before audio
> quality takes a severe nose dive.

-- 
Gustavo Daniel Villarreal
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