I suggest you have a read of the Cisco Unified Videoconferencing Solution Reference Network Design (SRND) document and the Cisco Video and TelePresence Architecture Design Guide.
In regard to bandwidth consumption, you can control the call rates to a certain extent using the default call rate setting on the endpoint themselves, or with a VCS-Control.
For the multisite session with more than 4 participants, you will need an MCU/Bridge. You can use any modern standards compliant endpoint with the bridge. For multsite calls with 4 or less participants, the internal MCU (enabled with a multisite licence key on most Cisco endpoints) can be used.
Hope that helps.
Wayne
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Wayne
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