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Videoconferencing Links
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Online Learning and Meetings Resources
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Video Quality of Service (QoS)
Technical Bulletin, Feb. 19, 2004
Quality of Service (QoS) is determined by video queue size
and IP precedence. To ensure bi-directional QoS, both MOREnet and its
customers must enable IP precedence 5 on outbound video packets. MOREnet
marks all outbound video traffic as it leaves the MCUs and requires customers
to mark their packets as they leave their location.
For MOREnet to determine the correct bandwidth
allocation for a videoconference, customers must let MOREnet know how
many concurrent video sessions they will be running. Each video session
requires 420 Kbps of bandwidth. Cisco recommends
that no more than 75%
of the total bandwidth be used by the video queue. Following this guideline,
one T-1 line could carry a maximum
of three video sessions. If the calls go through a MOREnet MCU, however,
the additional overhead of MCU traffic will reduce the maximum number of
available video sessions to two. Customers who have only part of a
T-1 may only be able to run one video session at a time. In order to run
more concurrent sessions, customers will have to upgrade their circuit.
Since the video queue determines the amount of
video traffic that can pass unhindered, customers must notify
MOREnet when adding
codecs and/or sessions to their network. MOREnet will then adjust
the video queue on the customer's connection to MOREnet.
It is important to note that, even though all of the bandwidth
is not being used, video drops may occur if the queue is not large enough.
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