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Cisco AVVID Network Infrastructure Enterprise Quality of Service Design
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Chapter 4 QoS in an AVVID-Enabled Wide-Area Network
QoS Recommendations for WAN Aggregation Routers
Classifying and Provisioning for Video on the WAN Edge
On the WAN edges (both at the WAN-aggregator and the remote-branch), video conferencing traffic
should to be assigned to an LLQ. The video stream minimum bandwidth guarantee should be the size of
the stream plus an additional 20%. Also, the LLQ burst parameter should be set to 30000 bytes per 384
kbps stream.
Tip
Additional details on bandwidth provisioning for video conferencing are explained in the IP
Videoconferencing Solution Reference Network Design Guide.
In the following configuration for video only over a T1 link:
·
Video conferencing traffic is assigned to an LLQ.
·
All non-video traffic is assigned to a default queue for weighted-fair queueing.
class-map match-all VIDEO
match ip dscp af41
!
!
policy-map WAN-EDGE
class VIDEO
priority 460 30000
class class-default
fair-queue
Note
Remember that this policy does not take effect until it is bound to an interface with a service-policy
statement. Service-policy statements are discussed in the
section.
Classifying and Provisioning for Data on the WAN Edge
Most enterprises have many applications that can be considered mission-critical (Gold). However, if too
many applications are classified as mission-critical, they will contend amongst themselves for
bandwidth and the result will be a dampening QoS effectiveness. A regular FIFO link (with no QoS) is
scheduled in the exact same manner as a link where every application is provisioned as mission-critical.
Therefore, it is recommended that you classify a maximum of three applications as mission-critical
(Gold).
Mission-critical applications should be marked with different AF drop-preference values to distinguish
them from each other. These distinctions will provide more granular visibility in managing and
monitoring application traffic and aid in provisioning for future requirements.
Similar arguments can be made for having no more than three applications in a guaranteed-bandwidth
(Silver) class of applications. You should also mark these applications with different AF drop-preference
values.
Default traffic is automatically marked as best effort (DSCP 0). However, non-critical
bandwidth-intensive traffic could be marked differently, so that adverse policies could be applied to
control such traffic. These types of traffic can be described as "less-than best-effort", or "scavenger"
traffic.
For information on the recommended DSCP traffic classifications for data, see
.