Configuring
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Cisco IOS software provides many other tools for ensuring QoS, such as custom queuing, priority queuing, and weighted fair queuing. For further information and more detailed examples of QoS configuration, refer to the Cisco 1751 Router Software Configuration Guide.
Note QoS measures the level of network performance. It does not directly measure the quality of the voice signal.
Configuring VoIP on a Frame Relay link involves special considerations. These are discussed in the section “Configuring Frame Relay for VoIP.”
Need for Quality of Service
On a relatively
Figure 21 Bandwidth v. Quality of Service
Low bandwidth needs QoS
10689
High bandwidth
might not need QoS
IP Precedence
Use the ip precedence command to give voice packets a higher priority over other IP data traffic. Every IP packet is given a precedence level. In IP precedence, the numbers 1 through 5 identify classes for IP flows; the numbers 6 through 7 are used for network and backbone routing and updates. You can configure voice packets for higher priority by setting the IP precedence value to 5. Internal routers using weighted fair queuing will give these packets priority. This command only applies to VoIP dial peers. The following example sets the IP precedence to 5:
Router> enable
Password:
Router# configure terminal
Router(config)#
The ip precedence command should also be used if RSVP is not enabled and the user would like to give voice packets a higher priority over other IP data traffic.
Cisco 1751
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