Implementing Call Admission Control
To prevent oversubscription of VoIP networks, the number of voice calls allowed on the network must be limited. This section describes the configuration parameters for implementing CAC, which can prevent oversubscription of WAN resources.
Effects of Bandwidth Oversubscription
QoS tools such as queuing ensure that voice traffic receives priority over data traffic. However, if a network link is oversubscribed with too much voice traffic, data packets are dropped, and the remaining voice calls suffer because they must compete for bandwidth available to the low-latency queue.
Figure 7-5 illustrates the effect of voice oversubscription. Using LLQ, voice traffic is directed into a priority queue (PQ) while all other ...
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