voip bandwidth consumption

[tomchan]

I am using g.711 codec and have known that it would take about 90kbps with ethernet header per call. However, I was reading some article and came across this per call meant only one way direction. Since one call will be bi-directional, so it should take 180kbps. Thanks.

[Chris Deren]

Are you asking a question. Yes it will be around 180kbps over ethernet without compression for 2 call legs.

http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080094ae2.shtml

[tomchan]

Thanks, so one call takes 2 call legs and will take 180kbps. (g.711 with ethernet)

[dgahm]

That is true, but if you look at it from that perspective, then your T1 is a 3mb pipe, and your 100mb ethernet is 200mb of bandwidth. The usual convention is to refer to one side.

When you set Locations bandwidth in Call Manager it assumes 80kb per G711 call, when setting bandwidth in an IOS Gatekeeper it assumes 128kb (64kb in each direction)per call. When you are configuring QOS on a serial link it is bandwidth in one direction.

If you set Locations to 800, you better provision QOS on your T1 for 900kb of priority bandwidth, since that is what is really required. A bandwidth setting of 1280kb on a gatekeeper would be equivalent.

My point is that you just have to be careful to compare apples to apples, and understand the underlying assumptions.