Polycom QSX 3725-22370-001/B - Manual (Page 53)

Additional Information
Maximum Bandwidth Utilization in Low Bandwidth Environments
Most low bandwidth connections (e.g.- DSL) are asymmetrical—transmission speeds are
usually slower than reception speeds. The Transmit and Receive configurations of the
QSX 2.0 use this fact to fully utilize available bandwidth. Look at the following
example, where to QSX units are connected at different rates:
Transmit Speed Receive Speed
QSX1 384Kbps 1024Kbps
QSX2 128Kbps 1024Kbps
In this case, even though the QSX2 has a slower connection, the QSX1 can still transmit
data at 384Kbps and the QSX2 can receive it at that speed. The extra bandwidth
available allows you to share content with people, minimizing delays in delivering that
content to them.
Bandwidth Sharing versus Time Sharing
The QSX allows you to choose between two different modes of bandwidth sharing for
Web Viewers. Depending on the type and speed of connection that participants have to
the meeting, you can use one of these modes to optimize the quality of information
exchange.
Time Sharing
The Time Sharing mode was developed to accommodate web viewers in a low bandwidth
environment.
In the Time Sharing mode, current images will be uploaded to participating web viewers
on a rotating basis. For example, if 32Kbps is available for web viewing and there are
three (3) web viewers connected to the QSX, they will, in turn, use the full 32kbps to
upload images.
No matter how many web viewers are connected, the bandwidth used by each web
viewer will not exceed the maximum allowed value. Moreover, each web viewer still
works under normal bandwidth conditions.
The advantage of Time Sharing is that a web viewer will have the full amount of
bandwidth for a period of time to upload shared content. The disadvantage is that one
slow connection could affect the performance of the rest of the web viewers. If, for
example, the bandwidth allowed is 128Kpbs, but one of three web viewers has a 56Kbps
connection, then the real bandwidth usage will be:
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