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Cisco AVVID Network Infrastructure Enterprise Quality of Service Design
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Chapter 1 Overview
Why is Quality of Service Required for AVVID?
Video conferencing
Video conferencing has the same loss, delay, and delay variation requirements as voice, but the traffic
patterns of video conferencing are radically different from voice. For example, video conferencing
traffic has varying packet sizes and extremely variable packet rates (as shown in
.)
Figure 1-3
Video conferencing Bandwidth Requirements for a 384 kbps Session
Because of its bursty nature, video conferencing has two unique requirements in provisioning for
strict-priority bandwidth:
·
The LLQ must be provisioned to the stream-rate plus 20%.
·
The LLQ burst parameter must be provisioned to 30000 bytes per 384 kbps stream.
Quality of Service Requirements for Data
When addressing the QoS needs of data application traffic, keep the following in mind:
·
Profile applications to get a basic understanding of their network requirements and traffic patterns.
·
Don't over-engineer the provisioning. Instead, use the proven relative priority model (as explained
in the following section).
·
Use no more than four traffic classes, such as:
Gold (Mission-Critical)--Enterprise Resource Planning (ERP), transactional, in-house
software
Silver (Guaranteed-Bandwidth)--Streaming video, messaging, intranet
Bronze (Best-Effort and Default class)--Internet browsing, E-Mail
Less-than-Best-Effort (Optional; higher-drop preferences)--FTP, backups, Peer-to-Peer (P2P)
applications (Napster, KaZaa)
·
Do not assign more than 3 applications to each class of protected data traffic.
·
Use proactive provisioning polices before reactive policing policies.
·
Obtain executive endorsement of relative ranking of application priority (from a QoS perspective)
prior to committing to the actual policy implementation, to avoid potential derailing of the project.
"P" and "B" Frames
Differential/Predicted Frames
128-256 Bytes
"I" Frame
(Full-Sample Video)
1024-1518 Bytes
"I" Frame
(Full-Sample Video)
1024-1518 Bytes
35Kbps
15pps
30pps
600Kbps
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