Configure Frame Relay For Voip - Cisco WS C4224V 8FXS - 200Mbps Ethernet Switch Software Configuration Manual

Chapter 6 Configuring VoIP

Configure Frame Relay for VoIP

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For example, to enable VAD for VoIP dial peer 108, enter the following:
c4224(config)# Dial-peer voice 108 voip
c4224(config-dial-peer)# vad
When you are configuring VoIP, you need to take certain factors into
consideration so that it runs smoothly over Frame Relay. A public Frame Relay
cloud provides no QoS guarantee. For real-time traffic to be transmitted in a
timely manner, the data rate must not exceed the committed information rate
(CIR), or packets might be dropped. In addition, Frame Relay traffic shaping and
RSVP are mutually exclusive. This is particularly important to remember if
multiple data-link connection identifiers (DLCIs) are carried on a single interface.
For Frame Relay links with slow output rates (less than or equal to 64 kbps),
where data and voice are transmitted over the same permanent virtual circuit
(PVC), Cisco recommends the following solutions:
Separate DLCIs for voice and data—By providing a separate subinterface for
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voice and data, you can use the appropriate QoS tool per line. For example,
each DLCI would use 32 kbps of a 64-kbps line.
Apply adaptive traffic shaping to both DLCIs.
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Use RSVP or IP precedence to prioritize voice traffic.
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• Use compressed RTP to minimize voice packet size.
Use weighted fair queuing to manage voice traffic.
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Lower the maximum transmission unit (MTU) size—Voice packets are
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generally small. When you lower the MTU size (for example, to 300 bytes),
large data packets can be broken up into smaller data packets that can more
easily be interwoven with voice packets.
Lowering the MTU size impacts data throughput speed.
Note
Set CIR equal to line rate—Ensure that the data rate does not exceed the CIR
•
through generic traffic shaping.
Use RSVP or IP precedence to prioritize voice traffic.
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Use compressed RTP to minimize voice packet header size.
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Catalyst 4224 Access Gateway Switch Software Configuration Guide
Configure Frame Relay for VoIP
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